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Source file src/crypto/x509/x509.go

Documentation: crypto/x509

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package x509 parses X.509-encoded keys and certificates.
     6  package x509
     7  
     8  import (
     9  	"bytes"
    10  	"crypto"
    11  	"crypto/dsa"
    12  	"crypto/ecdsa"
    13  	"crypto/ed25519"
    14  	"crypto/elliptic"
    15  	"crypto/rsa"
    16  	"crypto/sha1"
    17  	"crypto/x509/pkix"
    18  	"encoding/asn1"
    19  	"encoding/pem"
    20  	"errors"
    21  	"fmt"
    22  	"io"
    23  	"math/big"
    24  	"net"
    25  	"net/url"
    26  	"strconv"
    27  	"strings"
    28  	"time"
    29  	"unicode"
    30  
    31  	// Explicitly import these for their crypto.RegisterHash init side-effects.
    32  	// Keep these as blank imports, even if they're imported above.
    33  	_ "crypto/sha1"
    34  	_ "crypto/sha256"
    35  	_ "crypto/sha512"
    36  
    37  	"golang.org/x/crypto/cryptobyte"
    38  	cryptobyte_asn1 "golang.org/x/crypto/cryptobyte/asn1"
    39  )
    40  
    41  // pkixPublicKey reflects a PKIX public key structure. See SubjectPublicKeyInfo
    42  // in RFC 3280.
    43  type pkixPublicKey struct {
    44  	Algo      pkix.AlgorithmIdentifier
    45  	BitString asn1.BitString
    46  }
    47  
    48  // ParsePKIXPublicKey parses a public key in PKIX, ASN.1 DER form.
    49  // The encoded public key is a SubjectPublicKeyInfo structure
    50  // (see RFC 5280, Section 4.1).
    51  //
    52  // It returns a *rsa.PublicKey, *dsa.PublicKey, *ecdsa.PublicKey, or
    53  // ed25519.PublicKey. More types might be supported in the future.
    54  //
    55  // This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
    56  func ParsePKIXPublicKey(derBytes []byte) (pub interface{}, err error) {
    57  	var pki publicKeyInfo
    58  	if rest, err := asn1.Unmarshal(derBytes, &pki); err != nil {
    59  		if _, err := asn1.Unmarshal(derBytes, &pkcs1PublicKey{}); err == nil {
    60  			return nil, errors.New("x509: failed to parse public key (use ParsePKCS1PublicKey instead for this key format)")
    61  		}
    62  		return nil, err
    63  	} else if len(rest) != 0 {
    64  		return nil, errors.New("x509: trailing data after ASN.1 of public-key")
    65  	}
    66  	algo := getPublicKeyAlgorithmFromOID(pki.Algorithm.Algorithm)
    67  	if algo == UnknownPublicKeyAlgorithm {
    68  		return nil, errors.New("x509: unknown public key algorithm")
    69  	}
    70  	return parsePublicKey(algo, &pki)
    71  }
    72  
    73  func marshalPublicKey(pub interface{}) (publicKeyBytes []byte, publicKeyAlgorithm pkix.AlgorithmIdentifier, err error) {
    74  	switch pub := pub.(type) {
    75  	case *rsa.PublicKey:
    76  		publicKeyBytes, err = asn1.Marshal(pkcs1PublicKey{
    77  			N: pub.N,
    78  			E: pub.E,
    79  		})
    80  		if err != nil {
    81  			return nil, pkix.AlgorithmIdentifier{}, err
    82  		}
    83  		publicKeyAlgorithm.Algorithm = oidPublicKeyRSA
    84  		// This is a NULL parameters value which is required by
    85  		// RFC 3279, Section 2.3.1.
    86  		publicKeyAlgorithm.Parameters = asn1.NullRawValue
    87  	case *ecdsa.PublicKey:
    88  		publicKeyBytes = elliptic.Marshal(pub.Curve, pub.X, pub.Y)
    89  		oid, ok := oidFromNamedCurve(pub.Curve)
    90  		if !ok {
    91  			return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
    92  		}
    93  		publicKeyAlgorithm.Algorithm = oidPublicKeyECDSA
    94  		var paramBytes []byte
    95  		paramBytes, err = asn1.Marshal(oid)
    96  		if err != nil {
    97  			return
    98  		}
    99  		publicKeyAlgorithm.Parameters.FullBytes = paramBytes
   100  	case ed25519.PublicKey:
   101  		publicKeyBytes = pub
   102  		publicKeyAlgorithm.Algorithm = oidPublicKeyEd25519
   103  	default:
   104  		return nil, pkix.AlgorithmIdentifier{}, fmt.Errorf("x509: unsupported public key type: %T", pub)
   105  	}
   106  
   107  	return publicKeyBytes, publicKeyAlgorithm, nil
   108  }
   109  
   110  // MarshalPKIXPublicKey converts a public key to PKIX, ASN.1 DER form.
   111  // The encoded public key is a SubjectPublicKeyInfo structure
   112  // (see RFC 5280, Section 4.1).
   113  //
   114  // The following key types are currently supported: *rsa.PublicKey, *ecdsa.PublicKey
   115  // and ed25519.PublicKey. Unsupported key types result in an error.
   116  //
   117  // This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
   118  func MarshalPKIXPublicKey(pub interface{}) ([]byte, error) {
   119  	var publicKeyBytes []byte
   120  	var publicKeyAlgorithm pkix.AlgorithmIdentifier
   121  	var err error
   122  
   123  	if publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(pub); err != nil {
   124  		return nil, err
   125  	}
   126  
   127  	pkix := pkixPublicKey{
   128  		Algo: publicKeyAlgorithm,
   129  		BitString: asn1.BitString{
   130  			Bytes:     publicKeyBytes,
   131  			BitLength: 8 * len(publicKeyBytes),
   132  		},
   133  	}
   134  
   135  	ret, _ := asn1.Marshal(pkix)
   136  	return ret, nil
   137  }
   138  
   139  // These structures reflect the ASN.1 structure of X.509 certificates.:
   140  
   141  type certificate struct {
   142  	Raw                asn1.RawContent
   143  	TBSCertificate     tbsCertificate
   144  	SignatureAlgorithm pkix.AlgorithmIdentifier
   145  	SignatureValue     asn1.BitString
   146  }
   147  
   148  type tbsCertificate struct {
   149  	Raw                asn1.RawContent
   150  	Version            int `asn1:"optional,explicit,default:0,tag:0"`
   151  	SerialNumber       *big.Int
   152  	SignatureAlgorithm pkix.AlgorithmIdentifier
   153  	Issuer             asn1.RawValue
   154  	Validity           validity
   155  	Subject            asn1.RawValue
   156  	PublicKey          publicKeyInfo
   157  	UniqueId           asn1.BitString   `asn1:"optional,tag:1"`
   158  	SubjectUniqueId    asn1.BitString   `asn1:"optional,tag:2"`
   159  	Extensions         []pkix.Extension `asn1:"optional,explicit,tag:3"`
   160  }
   161  
   162  type dsaAlgorithmParameters struct {
   163  	P, Q, G *big.Int
   164  }
   165  
   166  type validity struct {
   167  	NotBefore, NotAfter time.Time
   168  }
   169  
   170  type publicKeyInfo struct {
   171  	Raw       asn1.RawContent
   172  	Algorithm pkix.AlgorithmIdentifier
   173  	PublicKey asn1.BitString
   174  }
   175  
   176  // RFC 5280,  4.2.1.1
   177  type authKeyId struct {
   178  	Id []byte `asn1:"optional,tag:0"`
   179  }
   180  
   181  type SignatureAlgorithm int
   182  
   183  const (
   184  	UnknownSignatureAlgorithm SignatureAlgorithm = iota
   185  
   186  	MD2WithRSA // Unsupported.
   187  	MD5WithRSA // Only supported for signing, not verification.
   188  	SHA1WithRSA
   189  	SHA256WithRSA
   190  	SHA384WithRSA
   191  	SHA512WithRSA
   192  	DSAWithSHA1   // Unsupported.
   193  	DSAWithSHA256 // Unsupported.
   194  	ECDSAWithSHA1
   195  	ECDSAWithSHA256
   196  	ECDSAWithSHA384
   197  	ECDSAWithSHA512
   198  	SHA256WithRSAPSS
   199  	SHA384WithRSAPSS
   200  	SHA512WithRSAPSS
   201  	PureEd25519
   202  )
   203  
   204  func (algo SignatureAlgorithm) isRSAPSS() bool {
   205  	switch algo {
   206  	case SHA256WithRSAPSS, SHA384WithRSAPSS, SHA512WithRSAPSS:
   207  		return true
   208  	default:
   209  		return false
   210  	}
   211  }
   212  
   213  func (algo SignatureAlgorithm) String() string {
   214  	for _, details := range signatureAlgorithmDetails {
   215  		if details.algo == algo {
   216  			return details.name
   217  		}
   218  	}
   219  	return strconv.Itoa(int(algo))
   220  }
   221  
   222  type PublicKeyAlgorithm int
   223  
   224  const (
   225  	UnknownPublicKeyAlgorithm PublicKeyAlgorithm = iota
   226  	RSA
   227  	DSA // Unsupported.
   228  	ECDSA
   229  	Ed25519
   230  )
   231  
   232  var publicKeyAlgoName = [...]string{
   233  	RSA:     "RSA",
   234  	DSA:     "DSA",
   235  	ECDSA:   "ECDSA",
   236  	Ed25519: "Ed25519",
   237  }
   238  
   239  func (algo PublicKeyAlgorithm) String() string {
   240  	if 0 < algo && int(algo) < len(publicKeyAlgoName) {
   241  		return publicKeyAlgoName[algo]
   242  	}
   243  	return strconv.Itoa(int(algo))
   244  }
   245  
   246  // OIDs for signature algorithms
   247  //
   248  // pkcs-1 OBJECT IDENTIFIER ::= {
   249  //    iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }
   250  //
   251  //
   252  // RFC 3279 2.2.1 RSA Signature Algorithms
   253  //
   254  // md2WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 2 }
   255  //
   256  // md5WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 4 }
   257  //
   258  // sha-1WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 5 }
   259  //
   260  // dsaWithSha1 OBJECT IDENTIFIER ::= {
   261  //    iso(1) member-body(2) us(840) x9-57(10040) x9cm(4) 3 }
   262  //
   263  // RFC 3279 2.2.3 ECDSA Signature Algorithm
   264  //
   265  // ecdsa-with-SHA1 OBJECT IDENTIFIER ::= {
   266  // 	  iso(1) member-body(2) us(840) ansi-x962(10045)
   267  //    signatures(4) ecdsa-with-SHA1(1)}
   268  //
   269  //
   270  // RFC 4055 5 PKCS #1 Version 1.5
   271  //
   272  // sha256WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 11 }
   273  //
   274  // sha384WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 12 }
   275  //
   276  // sha512WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 13 }
   277  //
   278  //
   279  // RFC 5758 3.1 DSA Signature Algorithms
   280  //
   281  // dsaWithSha256 OBJECT IDENTIFIER ::= {
   282  //    joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101)
   283  //    csor(3) algorithms(4) id-dsa-with-sha2(3) 2}
   284  //
   285  // RFC 5758 3.2 ECDSA Signature Algorithm
   286  //
   287  // ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   288  //    us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 2 }
   289  //
   290  // ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   291  //    us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 3 }
   292  //
   293  // ecdsa-with-SHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   294  //    us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 4 }
   295  //
   296  //
   297  // RFC 8410 3 Curve25519 and Curve448 Algorithm Identifiers
   298  //
   299  // id-Ed25519   OBJECT IDENTIFIER ::= { 1 3 101 112 }
   300  
   301  var (
   302  	oidSignatureMD2WithRSA      = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 2}
   303  	oidSignatureMD5WithRSA      = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 4}
   304  	oidSignatureSHA1WithRSA     = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 5}
   305  	oidSignatureSHA256WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 11}
   306  	oidSignatureSHA384WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 12}
   307  	oidSignatureSHA512WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 13}
   308  	oidSignatureRSAPSS          = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 10}
   309  	oidSignatureDSAWithSHA1     = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 3}
   310  	oidSignatureDSAWithSHA256   = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 3, 2}
   311  	oidSignatureECDSAWithSHA1   = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 1}
   312  	oidSignatureECDSAWithSHA256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 2}
   313  	oidSignatureECDSAWithSHA384 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 3}
   314  	oidSignatureECDSAWithSHA512 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 4}
   315  	oidSignatureEd25519         = asn1.ObjectIdentifier{1, 3, 101, 112}
   316  
   317  	oidSHA256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 1}
   318  	oidSHA384 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 2}
   319  	oidSHA512 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 3}
   320  
   321  	oidMGF1 = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 8}
   322  
   323  	// oidISOSignatureSHA1WithRSA means the same as oidSignatureSHA1WithRSA
   324  	// but it's specified by ISO. Microsoft's makecert.exe has been known
   325  	// to produce certificates with this OID.
   326  	oidISOSignatureSHA1WithRSA = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 29}
   327  )
   328  
   329  var signatureAlgorithmDetails = []struct {
   330  	algo       SignatureAlgorithm
   331  	name       string
   332  	oid        asn1.ObjectIdentifier
   333  	pubKeyAlgo PublicKeyAlgorithm
   334  	hash       crypto.Hash
   335  }{
   336  	{MD2WithRSA, "MD2-RSA", oidSignatureMD2WithRSA, RSA, crypto.Hash(0) /* no value for MD2 */},
   337  	{MD5WithRSA, "MD5-RSA", oidSignatureMD5WithRSA, RSA, crypto.MD5},
   338  	{SHA1WithRSA, "SHA1-RSA", oidSignatureSHA1WithRSA, RSA, crypto.SHA1},
   339  	{SHA1WithRSA, "SHA1-RSA", oidISOSignatureSHA1WithRSA, RSA, crypto.SHA1},
   340  	{SHA256WithRSA, "SHA256-RSA", oidSignatureSHA256WithRSA, RSA, crypto.SHA256},
   341  	{SHA384WithRSA, "SHA384-RSA", oidSignatureSHA384WithRSA, RSA, crypto.SHA384},
   342  	{SHA512WithRSA, "SHA512-RSA", oidSignatureSHA512WithRSA, RSA, crypto.SHA512},
   343  	{SHA256WithRSAPSS, "SHA256-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA256},
   344  	{SHA384WithRSAPSS, "SHA384-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA384},
   345  	{SHA512WithRSAPSS, "SHA512-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA512},
   346  	{DSAWithSHA1, "DSA-SHA1", oidSignatureDSAWithSHA1, DSA, crypto.SHA1},
   347  	{DSAWithSHA256, "DSA-SHA256", oidSignatureDSAWithSHA256, DSA, crypto.SHA256},
   348  	{ECDSAWithSHA1, "ECDSA-SHA1", oidSignatureECDSAWithSHA1, ECDSA, crypto.SHA1},
   349  	{ECDSAWithSHA256, "ECDSA-SHA256", oidSignatureECDSAWithSHA256, ECDSA, crypto.SHA256},
   350  	{ECDSAWithSHA384, "ECDSA-SHA384", oidSignatureECDSAWithSHA384, ECDSA, crypto.SHA384},
   351  	{ECDSAWithSHA512, "ECDSA-SHA512", oidSignatureECDSAWithSHA512, ECDSA, crypto.SHA512},
   352  	{PureEd25519, "Ed25519", oidSignatureEd25519, Ed25519, crypto.Hash(0) /* no pre-hashing */},
   353  }
   354  
   355  // hashToPSSParameters contains the DER encoded RSA PSS parameters for the
   356  // SHA256, SHA384, and SHA512 hashes as defined in RFC 3447, Appendix A.2.3.
   357  // The parameters contain the following values:
   358  //   * hashAlgorithm contains the associated hash identifier with NULL parameters
   359  //   * maskGenAlgorithm always contains the default mgf1SHA1 identifier
   360  //   * saltLength contains the length of the associated hash
   361  //   * trailerField always contains the default trailerFieldBC value
   362  var hashToPSSParameters = map[crypto.Hash]asn1.RawValue{
   363  	crypto.SHA256: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 1, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 1, 5, 0, 162, 3, 2, 1, 32}},
   364  	crypto.SHA384: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 2, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 2, 5, 0, 162, 3, 2, 1, 48}},
   365  	crypto.SHA512: asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 3, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 3, 5, 0, 162, 3, 2, 1, 64}},
   366  }
   367  
   368  // pssParameters reflects the parameters in an AlgorithmIdentifier that
   369  // specifies RSA PSS. See RFC 3447, Appendix A.2.3.
   370  type pssParameters struct {
   371  	// The following three fields are not marked as
   372  	// optional because the default values specify SHA-1,
   373  	// which is no longer suitable for use in signatures.
   374  	Hash         pkix.AlgorithmIdentifier `asn1:"explicit,tag:0"`
   375  	MGF          pkix.AlgorithmIdentifier `asn1:"explicit,tag:1"`
   376  	SaltLength   int                      `asn1:"explicit,tag:2"`
   377  	TrailerField int                      `asn1:"optional,explicit,tag:3,default:1"`
   378  }
   379  
   380  func getSignatureAlgorithmFromAI(ai pkix.AlgorithmIdentifier) SignatureAlgorithm {
   381  	if ai.Algorithm.Equal(oidSignatureEd25519) {
   382  		// RFC 8410, Section 3
   383  		// > For all of the OIDs, the parameters MUST be absent.
   384  		if len(ai.Parameters.FullBytes) != 0 {
   385  			return UnknownSignatureAlgorithm
   386  		}
   387  	}
   388  
   389  	if !ai.Algorithm.Equal(oidSignatureRSAPSS) {
   390  		for _, details := range signatureAlgorithmDetails {
   391  			if ai.Algorithm.Equal(details.oid) {
   392  				return details.algo
   393  			}
   394  		}
   395  		return UnknownSignatureAlgorithm
   396  	}
   397  
   398  	// RSA PSS is special because it encodes important parameters
   399  	// in the Parameters.
   400  
   401  	var params pssParameters
   402  	if _, err := asn1.Unmarshal(ai.Parameters.FullBytes, &params); err != nil {
   403  		return UnknownSignatureAlgorithm
   404  	}
   405  
   406  	var mgf1HashFunc pkix.AlgorithmIdentifier
   407  	if _, err := asn1.Unmarshal(params.MGF.Parameters.FullBytes, &mgf1HashFunc); err != nil {
   408  		return UnknownSignatureAlgorithm
   409  	}
   410  
   411  	// PSS is greatly overburdened with options. This code forces them into
   412  	// three buckets by requiring that the MGF1 hash function always match the
   413  	// message hash function (as recommended in RFC 3447, Section 8.1), that the
   414  	// salt length matches the hash length, and that the trailer field has the
   415  	// default value.
   416  	if (len(params.Hash.Parameters.FullBytes) != 0 && !bytes.Equal(params.Hash.Parameters.FullBytes, asn1.NullBytes)) ||
   417  		!params.MGF.Algorithm.Equal(oidMGF1) ||
   418  		!mgf1HashFunc.Algorithm.Equal(params.Hash.Algorithm) ||
   419  		(len(mgf1HashFunc.Parameters.FullBytes) != 0 && !bytes.Equal(mgf1HashFunc.Parameters.FullBytes, asn1.NullBytes)) ||
   420  		params.TrailerField != 1 {
   421  		return UnknownSignatureAlgorithm
   422  	}
   423  
   424  	switch {
   425  	case params.Hash.Algorithm.Equal(oidSHA256) && params.SaltLength == 32:
   426  		return SHA256WithRSAPSS
   427  	case params.Hash.Algorithm.Equal(oidSHA384) && params.SaltLength == 48:
   428  		return SHA384WithRSAPSS
   429  	case params.Hash.Algorithm.Equal(oidSHA512) && params.SaltLength == 64:
   430  		return SHA512WithRSAPSS
   431  	}
   432  
   433  	return UnknownSignatureAlgorithm
   434  }
   435  
   436  // RFC 3279, 2.3 Public Key Algorithms
   437  //
   438  // pkcs-1 OBJECT IDENTIFIER ::== { iso(1) member-body(2) us(840)
   439  //    rsadsi(113549) pkcs(1) 1 }
   440  //
   441  // rsaEncryption OBJECT IDENTIFIER ::== { pkcs1-1 1 }
   442  //
   443  // id-dsa OBJECT IDENTIFIER ::== { iso(1) member-body(2) us(840)
   444  //    x9-57(10040) x9cm(4) 1 }
   445  //
   446  // RFC 5480, 2.1.1 Unrestricted Algorithm Identifier and Parameters
   447  //
   448  // id-ecPublicKey OBJECT IDENTIFIER ::= {
   449  //       iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2) 1 }
   450  var (
   451  	oidPublicKeyRSA     = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 1}
   452  	oidPublicKeyDSA     = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 1}
   453  	oidPublicKeyECDSA   = asn1.ObjectIdentifier{1, 2, 840, 10045, 2, 1}
   454  	oidPublicKeyEd25519 = oidSignatureEd25519
   455  )
   456  
   457  func getPublicKeyAlgorithmFromOID(oid asn1.ObjectIdentifier) PublicKeyAlgorithm {
   458  	switch {
   459  	case oid.Equal(oidPublicKeyRSA):
   460  		return RSA
   461  	case oid.Equal(oidPublicKeyDSA):
   462  		return DSA
   463  	case oid.Equal(oidPublicKeyECDSA):
   464  		return ECDSA
   465  	case oid.Equal(oidPublicKeyEd25519):
   466  		return Ed25519
   467  	}
   468  	return UnknownPublicKeyAlgorithm
   469  }
   470  
   471  // RFC 5480, 2.1.1.1. Named Curve
   472  //
   473  // secp224r1 OBJECT IDENTIFIER ::= {
   474  //   iso(1) identified-organization(3) certicom(132) curve(0) 33 }
   475  //
   476  // secp256r1 OBJECT IDENTIFIER ::= {
   477  //   iso(1) member-body(2) us(840) ansi-X9-62(10045) curves(3)
   478  //   prime(1) 7 }
   479  //
   480  // secp384r1 OBJECT IDENTIFIER ::= {
   481  //   iso(1) identified-organization(3) certicom(132) curve(0) 34 }
   482  //
   483  // secp521r1 OBJECT IDENTIFIER ::= {
   484  //   iso(1) identified-organization(3) certicom(132) curve(0) 35 }
   485  //
   486  // NB: secp256r1 is equivalent to prime256v1
   487  var (
   488  	oidNamedCurveP224 = asn1.ObjectIdentifier{1, 3, 132, 0, 33}
   489  	oidNamedCurveP256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 3, 1, 7}
   490  	oidNamedCurveP384 = asn1.ObjectIdentifier{1, 3, 132, 0, 34}
   491  	oidNamedCurveP521 = asn1.ObjectIdentifier{1, 3, 132, 0, 35}
   492  )
   493  
   494  func namedCurveFromOID(oid asn1.ObjectIdentifier) elliptic.Curve {
   495  	switch {
   496  	case oid.Equal(oidNamedCurveP224):
   497  		return elliptic.P224()
   498  	case oid.Equal(oidNamedCurveP256):
   499  		return elliptic.P256()
   500  	case oid.Equal(oidNamedCurveP384):
   501  		return elliptic.P384()
   502  	case oid.Equal(oidNamedCurveP521):
   503  		return elliptic.P521()
   504  	}
   505  	return nil
   506  }
   507  
   508  func oidFromNamedCurve(curve elliptic.Curve) (asn1.ObjectIdentifier, bool) {
   509  	switch curve {
   510  	case elliptic.P224():
   511  		return oidNamedCurveP224, true
   512  	case elliptic.P256():
   513  		return oidNamedCurveP256, true
   514  	case elliptic.P384():
   515  		return oidNamedCurveP384, true
   516  	case elliptic.P521():
   517  		return oidNamedCurveP521, true
   518  	}
   519  
   520  	return nil, false
   521  }
   522  
   523  // KeyUsage represents the set of actions that are valid for a given key. It's
   524  // a bitmap of the KeyUsage* constants.
   525  type KeyUsage int
   526  
   527  const (
   528  	KeyUsageDigitalSignature KeyUsage = 1 << iota
   529  	KeyUsageContentCommitment
   530  	KeyUsageKeyEncipherment
   531  	KeyUsageDataEncipherment
   532  	KeyUsageKeyAgreement
   533  	KeyUsageCertSign
   534  	KeyUsageCRLSign
   535  	KeyUsageEncipherOnly
   536  	KeyUsageDecipherOnly
   537  )
   538  
   539  // RFC 5280, 4.2.1.12  Extended Key Usage
   540  //
   541  // anyExtendedKeyUsage OBJECT IDENTIFIER ::= { id-ce-extKeyUsage 0 }
   542  //
   543  // id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
   544  //
   545  // id-kp-serverAuth             OBJECT IDENTIFIER ::= { id-kp 1 }
   546  // id-kp-clientAuth             OBJECT IDENTIFIER ::= { id-kp 2 }
   547  // id-kp-codeSigning            OBJECT IDENTIFIER ::= { id-kp 3 }
   548  // id-kp-emailProtection        OBJECT IDENTIFIER ::= { id-kp 4 }
   549  // id-kp-timeStamping           OBJECT IDENTIFIER ::= { id-kp 8 }
   550  // id-kp-OCSPSigning            OBJECT IDENTIFIER ::= { id-kp 9 }
   551  var (
   552  	oidExtKeyUsageAny                            = asn1.ObjectIdentifier{2, 5, 29, 37, 0}
   553  	oidExtKeyUsageServerAuth                     = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 1}
   554  	oidExtKeyUsageClientAuth                     = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 2}
   555  	oidExtKeyUsageCodeSigning                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 3}
   556  	oidExtKeyUsageEmailProtection                = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 4}
   557  	oidExtKeyUsageIPSECEndSystem                 = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 5}
   558  	oidExtKeyUsageIPSECTunnel                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 6}
   559  	oidExtKeyUsageIPSECUser                      = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 7}
   560  	oidExtKeyUsageTimeStamping                   = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 8}
   561  	oidExtKeyUsageOCSPSigning                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 9}
   562  	oidExtKeyUsageMicrosoftServerGatedCrypto     = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 10, 3, 3}
   563  	oidExtKeyUsageNetscapeServerGatedCrypto      = asn1.ObjectIdentifier{2, 16, 840, 1, 113730, 4, 1}
   564  	oidExtKeyUsageMicrosoftCommercialCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 2, 1, 22}
   565  	oidExtKeyUsageMicrosoftKernelCodeSigning     = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 61, 1, 1}
   566  )
   567  
   568  // ExtKeyUsage represents an extended set of actions that are valid for a given key.
   569  // Each of the ExtKeyUsage* constants define a unique action.
   570  type ExtKeyUsage int
   571  
   572  const (
   573  	ExtKeyUsageAny ExtKeyUsage = iota
   574  	ExtKeyUsageServerAuth
   575  	ExtKeyUsageClientAuth
   576  	ExtKeyUsageCodeSigning
   577  	ExtKeyUsageEmailProtection
   578  	ExtKeyUsageIPSECEndSystem
   579  	ExtKeyUsageIPSECTunnel
   580  	ExtKeyUsageIPSECUser
   581  	ExtKeyUsageTimeStamping
   582  	ExtKeyUsageOCSPSigning
   583  	ExtKeyUsageMicrosoftServerGatedCrypto
   584  	ExtKeyUsageNetscapeServerGatedCrypto
   585  	ExtKeyUsageMicrosoftCommercialCodeSigning
   586  	ExtKeyUsageMicrosoftKernelCodeSigning
   587  )
   588  
   589  // extKeyUsageOIDs contains the mapping between an ExtKeyUsage and its OID.
   590  var extKeyUsageOIDs = []struct {
   591  	extKeyUsage ExtKeyUsage
   592  	oid         asn1.ObjectIdentifier
   593  }{
   594  	{ExtKeyUsageAny, oidExtKeyUsageAny},
   595  	{ExtKeyUsageServerAuth, oidExtKeyUsageServerAuth},
   596  	{ExtKeyUsageClientAuth, oidExtKeyUsageClientAuth},
   597  	{ExtKeyUsageCodeSigning, oidExtKeyUsageCodeSigning},
   598  	{ExtKeyUsageEmailProtection, oidExtKeyUsageEmailProtection},
   599  	{ExtKeyUsageIPSECEndSystem, oidExtKeyUsageIPSECEndSystem},
   600  	{ExtKeyUsageIPSECTunnel, oidExtKeyUsageIPSECTunnel},
   601  	{ExtKeyUsageIPSECUser, oidExtKeyUsageIPSECUser},
   602  	{ExtKeyUsageTimeStamping, oidExtKeyUsageTimeStamping},
   603  	{ExtKeyUsageOCSPSigning, oidExtKeyUsageOCSPSigning},
   604  	{ExtKeyUsageMicrosoftServerGatedCrypto, oidExtKeyUsageMicrosoftServerGatedCrypto},
   605  	{ExtKeyUsageNetscapeServerGatedCrypto, oidExtKeyUsageNetscapeServerGatedCrypto},
   606  	{ExtKeyUsageMicrosoftCommercialCodeSigning, oidExtKeyUsageMicrosoftCommercialCodeSigning},
   607  	{ExtKeyUsageMicrosoftKernelCodeSigning, oidExtKeyUsageMicrosoftKernelCodeSigning},
   608  }
   609  
   610  func extKeyUsageFromOID(oid asn1.ObjectIdentifier) (eku ExtKeyUsage, ok bool) {
   611  	for _, pair := range extKeyUsageOIDs {
   612  		if oid.Equal(pair.oid) {
   613  			return pair.extKeyUsage, true
   614  		}
   615  	}
   616  	return
   617  }
   618  
   619  func oidFromExtKeyUsage(eku ExtKeyUsage) (oid asn1.ObjectIdentifier, ok bool) {
   620  	for _, pair := range extKeyUsageOIDs {
   621  		if eku == pair.extKeyUsage {
   622  			return pair.oid, true
   623  		}
   624  	}
   625  	return
   626  }
   627  
   628  // A Certificate represents an X.509 certificate.
   629  type Certificate struct {
   630  	Raw                     []byte // Complete ASN.1 DER content (certificate, signature algorithm and signature).
   631  	RawTBSCertificate       []byte // Certificate part of raw ASN.1 DER content.
   632  	RawSubjectPublicKeyInfo []byte // DER encoded SubjectPublicKeyInfo.
   633  	RawSubject              []byte // DER encoded Subject
   634  	RawIssuer               []byte // DER encoded Issuer
   635  
   636  	Signature          []byte
   637  	SignatureAlgorithm SignatureAlgorithm
   638  
   639  	PublicKeyAlgorithm PublicKeyAlgorithm
   640  	PublicKey          interface{}
   641  
   642  	Version             int
   643  	SerialNumber        *big.Int
   644  	Issuer              pkix.Name
   645  	Subject             pkix.Name
   646  	NotBefore, NotAfter time.Time // Validity bounds.
   647  	KeyUsage            KeyUsage
   648  
   649  	// Extensions contains raw X.509 extensions. When parsing certificates,
   650  	// this can be used to extract non-critical extensions that are not
   651  	// parsed by this package. When marshaling certificates, the Extensions
   652  	// field is ignored, see ExtraExtensions.
   653  	Extensions []pkix.Extension
   654  
   655  	// ExtraExtensions contains extensions to be copied, raw, into any
   656  	// marshaled certificates. Values override any extensions that would
   657  	// otherwise be produced based on the other fields. The ExtraExtensions
   658  	// field is not populated when parsing certificates, see Extensions.
   659  	ExtraExtensions []pkix.Extension
   660  
   661  	// UnhandledCriticalExtensions contains a list of extension IDs that
   662  	// were not (fully) processed when parsing. Verify will fail if this
   663  	// slice is non-empty, unless verification is delegated to an OS
   664  	// library which understands all the critical extensions.
   665  	//
   666  	// Users can access these extensions using Extensions and can remove
   667  	// elements from this slice if they believe that they have been
   668  	// handled.
   669  	UnhandledCriticalExtensions []asn1.ObjectIdentifier
   670  
   671  	ExtKeyUsage        []ExtKeyUsage           // Sequence of extended key usages.
   672  	UnknownExtKeyUsage []asn1.ObjectIdentifier // Encountered extended key usages unknown to this package.
   673  
   674  	// BasicConstraintsValid indicates whether IsCA, MaxPathLen,
   675  	// and MaxPathLenZero are valid.
   676  	BasicConstraintsValid bool
   677  	IsCA                  bool
   678  
   679  	// MaxPathLen and MaxPathLenZero indicate the presence and
   680  	// value of the BasicConstraints' "pathLenConstraint".
   681  	//
   682  	// When parsing a certificate, a positive non-zero MaxPathLen
   683  	// means that the field was specified, -1 means it was unset,
   684  	// and MaxPathLenZero being true mean that the field was
   685  	// explicitly set to zero. The case of MaxPathLen==0 with MaxPathLenZero==false
   686  	// should be treated equivalent to -1 (unset).
   687  	//
   688  	// When generating a certificate, an unset pathLenConstraint
   689  	// can be requested with either MaxPathLen == -1 or using the
   690  	// zero value for both MaxPathLen and MaxPathLenZero.
   691  	MaxPathLen int
   692  	// MaxPathLenZero indicates that BasicConstraintsValid==true
   693  	// and MaxPathLen==0 should be interpreted as an actual
   694  	// maximum path length of zero. Otherwise, that combination is
   695  	// interpreted as MaxPathLen not being set.
   696  	MaxPathLenZero bool
   697  
   698  	SubjectKeyId   []byte
   699  	AuthorityKeyId []byte
   700  
   701  	// RFC 5280, 4.2.2.1 (Authority Information Access)
   702  	OCSPServer            []string
   703  	IssuingCertificateURL []string
   704  
   705  	// Subject Alternate Name values. (Note that these values may not be valid
   706  	// if invalid values were contained within a parsed certificate. For
   707  	// example, an element of DNSNames may not be a valid DNS domain name.)
   708  	DNSNames       []string
   709  	EmailAddresses []string
   710  	IPAddresses    []net.IP
   711  	URIs           []*url.URL
   712  
   713  	// Name constraints
   714  	PermittedDNSDomainsCritical bool // if true then the name constraints are marked critical.
   715  	PermittedDNSDomains         []string
   716  	ExcludedDNSDomains          []string
   717  	PermittedIPRanges           []*net.IPNet
   718  	ExcludedIPRanges            []*net.IPNet
   719  	PermittedEmailAddresses     []string
   720  	ExcludedEmailAddresses      []string
   721  	PermittedURIDomains         []string
   722  	ExcludedURIDomains          []string
   723  
   724  	// CRL Distribution Points
   725  	CRLDistributionPoints []string
   726  
   727  	PolicyIdentifiers []asn1.ObjectIdentifier
   728  }
   729  
   730  // ErrUnsupportedAlgorithm results from attempting to perform an operation that
   731  // involves algorithms that are not currently implemented.
   732  var ErrUnsupportedAlgorithm = errors.New("x509: cannot verify signature: algorithm unimplemented")
   733  
   734  // An InsecureAlgorithmError
   735  type InsecureAlgorithmError SignatureAlgorithm
   736  
   737  func (e InsecureAlgorithmError) Error() string {
   738  	return fmt.Sprintf("x509: cannot verify signature: insecure algorithm %v", SignatureAlgorithm(e))
   739  }
   740  
   741  // ConstraintViolationError results when a requested usage is not permitted by
   742  // a certificate. For example: checking a signature when the public key isn't a
   743  // certificate signing key.
   744  type ConstraintViolationError struct{}
   745  
   746  func (ConstraintViolationError) Error() string {
   747  	return "x509: invalid signature: parent certificate cannot sign this kind of certificate"
   748  }
   749  
   750  func (c *Certificate) Equal(other *Certificate) bool {
   751  	if c == nil || other == nil {
   752  		return c == other
   753  	}
   754  	return bytes.Equal(c.Raw, other.Raw)
   755  }
   756  
   757  func (c *Certificate) hasSANExtension() bool {
   758  	return oidInExtensions(oidExtensionSubjectAltName, c.Extensions)
   759  }
   760  
   761  // CheckSignatureFrom verifies that the signature on c is a valid signature
   762  // from parent.
   763  func (c *Certificate) CheckSignatureFrom(parent *Certificate) error {
   764  	// RFC 5280, 4.2.1.9:
   765  	// "If the basic constraints extension is not present in a version 3
   766  	// certificate, or the extension is present but the cA boolean is not
   767  	// asserted, then the certified public key MUST NOT be used to verify
   768  	// certificate signatures."
   769  	if parent.Version == 3 && !parent.BasicConstraintsValid ||
   770  		parent.BasicConstraintsValid && !parent.IsCA {
   771  		return ConstraintViolationError{}
   772  	}
   773  
   774  	if parent.KeyUsage != 0 && parent.KeyUsage&KeyUsageCertSign == 0 {
   775  		return ConstraintViolationError{}
   776  	}
   777  
   778  	if parent.PublicKeyAlgorithm == UnknownPublicKeyAlgorithm {
   779  		return ErrUnsupportedAlgorithm
   780  	}
   781  
   782  	// TODO(agl): don't ignore the path length constraint.
   783  
   784  	return parent.CheckSignature(c.SignatureAlgorithm, c.RawTBSCertificate, c.Signature)
   785  }
   786  
   787  // CheckSignature verifies that signature is a valid signature over signed from
   788  // c's public key.
   789  func (c *Certificate) CheckSignature(algo SignatureAlgorithm, signed, signature []byte) error {
   790  	return checkSignature(algo, signed, signature, c.PublicKey)
   791  }
   792  
   793  func (c *Certificate) hasNameConstraints() bool {
   794  	return oidInExtensions(oidExtensionNameConstraints, c.Extensions)
   795  }
   796  
   797  func (c *Certificate) getSANExtension() []byte {
   798  	for _, e := range c.Extensions {
   799  		if e.Id.Equal(oidExtensionSubjectAltName) {
   800  			return e.Value
   801  		}
   802  	}
   803  	return nil
   804  }
   805  
   806  func signaturePublicKeyAlgoMismatchError(expectedPubKeyAlgo PublicKeyAlgorithm, pubKey interface{}) error {
   807  	return fmt.Errorf("x509: signature algorithm specifies an %s public key, but have public key of type %T", expectedPubKeyAlgo.String(), pubKey)
   808  }
   809  
   810  // CheckSignature verifies that signature is a valid signature over signed from
   811  // a crypto.PublicKey.
   812  func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey crypto.PublicKey) (err error) {
   813  	var hashType crypto.Hash
   814  	var pubKeyAlgo PublicKeyAlgorithm
   815  
   816  	for _, details := range signatureAlgorithmDetails {
   817  		if details.algo == algo {
   818  			hashType = details.hash
   819  			pubKeyAlgo = details.pubKeyAlgo
   820  		}
   821  	}
   822  
   823  	switch hashType {
   824  	case crypto.Hash(0):
   825  		if pubKeyAlgo != Ed25519 {
   826  			return ErrUnsupportedAlgorithm
   827  		}
   828  	case crypto.MD5:
   829  		return InsecureAlgorithmError(algo)
   830  	default:
   831  		if !hashType.Available() {
   832  			return ErrUnsupportedAlgorithm
   833  		}
   834  		h := hashType.New()
   835  		h.Write(signed)
   836  		signed = h.Sum(nil)
   837  	}
   838  
   839  	switch pub := publicKey.(type) {
   840  	case *rsa.PublicKey:
   841  		if pubKeyAlgo != RSA {
   842  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
   843  		}
   844  		if algo.isRSAPSS() {
   845  			return rsa.VerifyPSS(pub, hashType, signed, signature, &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash})
   846  		} else {
   847  			return rsa.VerifyPKCS1v15(pub, hashType, signed, signature)
   848  		}
   849  	case *ecdsa.PublicKey:
   850  		if pubKeyAlgo != ECDSA {
   851  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
   852  		}
   853  		if !ecdsa.VerifyASN1(pub, signed, signature) {
   854  			return errors.New("x509: ECDSA verification failure")
   855  		}
   856  		return
   857  	case ed25519.PublicKey:
   858  		if pubKeyAlgo != Ed25519 {
   859  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
   860  		}
   861  		if !ed25519.Verify(pub, signed, signature) {
   862  			return errors.New("x509: Ed25519 verification failure")
   863  		}
   864  		return
   865  	}
   866  	return ErrUnsupportedAlgorithm
   867  }
   868  
   869  // CheckCRLSignature checks that the signature in crl is from c.
   870  func (c *Certificate) CheckCRLSignature(crl *pkix.CertificateList) error {
   871  	algo := getSignatureAlgorithmFromAI(crl.SignatureAlgorithm)
   872  	return c.CheckSignature(algo, crl.TBSCertList.Raw, crl.SignatureValue.RightAlign())
   873  }
   874  
   875  type UnhandledCriticalExtension struct{}
   876  
   877  func (h UnhandledCriticalExtension) Error() string {
   878  	return "x509: unhandled critical extension"
   879  }
   880  
   881  type basicConstraints struct {
   882  	IsCA       bool `asn1:"optional"`
   883  	MaxPathLen int  `asn1:"optional,default:-1"`
   884  }
   885  
   886  // RFC 5280 4.2.1.4
   887  type policyInformation struct {
   888  	Policy asn1.ObjectIdentifier
   889  	// policyQualifiers omitted
   890  }
   891  
   892  const (
   893  	nameTypeEmail = 1
   894  	nameTypeDNS   = 2
   895  	nameTypeURI   = 6
   896  	nameTypeIP    = 7
   897  )
   898  
   899  // RFC 5280, 4.2.2.1
   900  type authorityInfoAccess struct {
   901  	Method   asn1.ObjectIdentifier
   902  	Location asn1.RawValue
   903  }
   904  
   905  // RFC 5280, 4.2.1.14
   906  type distributionPoint struct {
   907  	DistributionPoint distributionPointName `asn1:"optional,tag:0"`
   908  	Reason            asn1.BitString        `asn1:"optional,tag:1"`
   909  	CRLIssuer         asn1.RawValue         `asn1:"optional,tag:2"`
   910  }
   911  
   912  type distributionPointName struct {
   913  	FullName     []asn1.RawValue  `asn1:"optional,tag:0"`
   914  	RelativeName pkix.RDNSequence `asn1:"optional,tag:1"`
   915  }
   916  
   917  func parsePublicKey(algo PublicKeyAlgorithm, keyData *publicKeyInfo) (interface{}, error) {
   918  	asn1Data := keyData.PublicKey.RightAlign()
   919  	switch algo {
   920  	case RSA:
   921  		// RSA public keys must have a NULL in the parameters.
   922  		// See RFC 3279, Section 2.3.1.
   923  		if !bytes.Equal(keyData.Algorithm.Parameters.FullBytes, asn1.NullBytes) {
   924  			return nil, errors.New("x509: RSA key missing NULL parameters")
   925  		}
   926  
   927  		p := new(pkcs1PublicKey)
   928  		rest, err := asn1.Unmarshal(asn1Data, p)
   929  		if err != nil {
   930  			return nil, err
   931  		}
   932  		if len(rest) != 0 {
   933  			return nil, errors.New("x509: trailing data after RSA public key")
   934  		}
   935  
   936  		if p.N.Sign() <= 0 {
   937  			return nil, errors.New("x509: RSA modulus is not a positive number")
   938  		}
   939  		if p.E <= 0 {
   940  			return nil, errors.New("x509: RSA public exponent is not a positive number")
   941  		}
   942  
   943  		pub := &rsa.PublicKey{
   944  			E: p.E,
   945  			N: p.N,
   946  		}
   947  		return pub, nil
   948  	case DSA:
   949  		var p *big.Int
   950  		rest, err := asn1.Unmarshal(asn1Data, &p)
   951  		if err != nil {
   952  			return nil, err
   953  		}
   954  		if len(rest) != 0 {
   955  			return nil, errors.New("x509: trailing data after DSA public key")
   956  		}
   957  		paramsData := keyData.Algorithm.Parameters.FullBytes
   958  		params := new(dsaAlgorithmParameters)
   959  		rest, err = asn1.Unmarshal(paramsData, params)
   960  		if err != nil {
   961  			return nil, err
   962  		}
   963  		if len(rest) != 0 {
   964  			return nil, errors.New("x509: trailing data after DSA parameters")
   965  		}
   966  		if p.Sign() <= 0 || params.P.Sign() <= 0 || params.Q.Sign() <= 0 || params.G.Sign() <= 0 {
   967  			return nil, errors.New("x509: zero or negative DSA parameter")
   968  		}
   969  		pub := &dsa.PublicKey{
   970  			Parameters: dsa.Parameters{
   971  				P: params.P,
   972  				Q: params.Q,
   973  				G: params.G,
   974  			},
   975  			Y: p,
   976  		}
   977  		return pub, nil
   978  	case ECDSA:
   979  		paramsData := keyData.Algorithm.Parameters.FullBytes
   980  		namedCurveOID := new(asn1.ObjectIdentifier)
   981  		rest, err := asn1.Unmarshal(paramsData, namedCurveOID)
   982  		if err != nil {
   983  			return nil, errors.New("x509: failed to parse ECDSA parameters as named curve")
   984  		}
   985  		if len(rest) != 0 {
   986  			return nil, errors.New("x509: trailing data after ECDSA parameters")
   987  		}
   988  		namedCurve := namedCurveFromOID(*namedCurveOID)
   989  		if namedCurve == nil {
   990  			return nil, errors.New("x509: unsupported elliptic curve")
   991  		}
   992  		x, y := elliptic.Unmarshal(namedCurve, asn1Data)
   993  		if x == nil {
   994  			return nil, errors.New("x509: failed to unmarshal elliptic curve point")
   995  		}
   996  		pub := &ecdsa.PublicKey{
   997  			Curve: namedCurve,
   998  			X:     x,
   999  			Y:     y,
  1000  		}
  1001  		return pub, nil
  1002  	case Ed25519:
  1003  		// RFC 8410, Section 3
  1004  		// > For all of the OIDs, the parameters MUST be absent.
  1005  		if len(keyData.Algorithm.Parameters.FullBytes) != 0 {
  1006  			return nil, errors.New("x509: Ed25519 key encoded with illegal parameters")
  1007  		}
  1008  		if len(asn1Data) != ed25519.PublicKeySize {
  1009  			return nil, errors.New("x509: wrong Ed25519 public key size")
  1010  		}
  1011  		pub := make([]byte, ed25519.PublicKeySize)
  1012  		copy(pub, asn1Data)
  1013  		return ed25519.PublicKey(pub), nil
  1014  	default:
  1015  		return nil, nil
  1016  	}
  1017  }
  1018  
  1019  func forEachSAN(extension []byte, callback func(tag int, data []byte) error) error {
  1020  	// RFC 5280, 4.2.1.6
  1021  
  1022  	// SubjectAltName ::= GeneralNames
  1023  	//
  1024  	// GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName
  1025  	//
  1026  	// GeneralName ::= CHOICE {
  1027  	//      otherName                       [0]     OtherName,
  1028  	//      rfc822Name                      [1]     IA5String,
  1029  	//      dNSName                         [2]     IA5String,
  1030  	//      x400Address                     [3]     ORAddress,
  1031  	//      directoryName                   [4]     Name,
  1032  	//      ediPartyName                    [5]     EDIPartyName,
  1033  	//      uniformResourceIdentifier       [6]     IA5String,
  1034  	//      iPAddress                       [7]     OCTET STRING,
  1035  	//      registeredID                    [8]     OBJECT IDENTIFIER }
  1036  	var seq asn1.RawValue
  1037  	rest, err := asn1.Unmarshal(extension, &seq)
  1038  	if err != nil {
  1039  		return err
  1040  	} else if len(rest) != 0 {
  1041  		return errors.New("x509: trailing data after X.509 extension")
  1042  	}
  1043  	if !seq.IsCompound || seq.Tag != 16 || seq.Class != 0 {
  1044  		return asn1.StructuralError{Msg: "bad SAN sequence"}
  1045  	}
  1046  
  1047  	rest = seq.Bytes
  1048  	for len(rest) > 0 {
  1049  		var v asn1.RawValue
  1050  		rest, err = asn1.Unmarshal(rest, &v)
  1051  		if err != nil {
  1052  			return err
  1053  		}
  1054  
  1055  		if err := callback(v.Tag, v.Bytes); err != nil {
  1056  			return err
  1057  		}
  1058  	}
  1059  
  1060  	return nil
  1061  }
  1062  
  1063  func parseSANExtension(value []byte) (dnsNames, emailAddresses []string, ipAddresses []net.IP, uris []*url.URL, err error) {
  1064  	err = forEachSAN(value, func(tag int, data []byte) error {
  1065  		switch tag {
  1066  		case nameTypeEmail:
  1067  			email := string(data)
  1068  			if err := isIA5String(email); err != nil {
  1069  				return errors.New("x509: SAN rfc822Name is malformed")
  1070  			}
  1071  			emailAddresses = append(emailAddresses, email)
  1072  		case nameTypeDNS:
  1073  			name := string(data)
  1074  			if err := isIA5String(name); err != nil {
  1075  				return errors.New("x509: SAN dNSName is malformed")
  1076  			}
  1077  			dnsNames = append(dnsNames, string(name))
  1078  		case nameTypeURI:
  1079  			uriStr := string(data)
  1080  			if err := isIA5String(uriStr); err != nil {
  1081  				return errors.New("x509: SAN uniformResourceIdentifier is malformed")
  1082  			}
  1083  			uri, err := url.Parse(uriStr)
  1084  			if err != nil {
  1085  				return fmt.Errorf("x509: cannot parse URI %q: %s", uriStr, err)
  1086  			}
  1087  			if len(uri.Host) > 0 {
  1088  				if _, ok := domainToReverseLabels(uri.Host); !ok {
  1089  					return fmt.Errorf("x509: cannot parse URI %q: invalid domain", uriStr)
  1090  				}
  1091  			}
  1092  			uris = append(uris, uri)
  1093  		case nameTypeIP:
  1094  			switch len(data) {
  1095  			case net.IPv4len, net.IPv6len:
  1096  				ipAddresses = append(ipAddresses, data)
  1097  			default:
  1098  				return errors.New("x509: cannot parse IP address of length " + strconv.Itoa(len(data)))
  1099  			}
  1100  		}
  1101  
  1102  		return nil
  1103  	})
  1104  
  1105  	return
  1106  }
  1107  
  1108  // isValidIPMask reports whether mask consists of zero or more 1 bits, followed by zero bits.
  1109  func isValidIPMask(mask []byte) bool {
  1110  	seenZero := false
  1111  
  1112  	for _, b := range mask {
  1113  		if seenZero {
  1114  			if b != 0 {
  1115  				return false
  1116  			}
  1117  
  1118  			continue
  1119  		}
  1120  
  1121  		switch b {
  1122  		case 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe:
  1123  			seenZero = true
  1124  		case 0xff:
  1125  		default:
  1126  			return false
  1127  		}
  1128  	}
  1129  
  1130  	return true
  1131  }
  1132  
  1133  func parseNameConstraintsExtension(out *Certificate, e pkix.Extension) (unhandled bool, err error) {
  1134  	// RFC 5280, 4.2.1.10
  1135  
  1136  	// NameConstraints ::= SEQUENCE {
  1137  	//      permittedSubtrees       [0]     GeneralSubtrees OPTIONAL,
  1138  	//      excludedSubtrees        [1]     GeneralSubtrees OPTIONAL }
  1139  	//
  1140  	// GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
  1141  	//
  1142  	// GeneralSubtree ::= SEQUENCE {
  1143  	//      base                    GeneralName,
  1144  	//      minimum         [0]     BaseDistance DEFAULT 0,
  1145  	//      maximum         [1]     BaseDistance OPTIONAL }
  1146  	//
  1147  	// BaseDistance ::= INTEGER (0..MAX)
  1148  
  1149  	outer := cryptobyte.String(e.Value)
  1150  	var toplevel, permitted, excluded cryptobyte.String
  1151  	var havePermitted, haveExcluded bool
  1152  	if !outer.ReadASN1(&toplevel, cryptobyte_asn1.SEQUENCE) ||
  1153  		!outer.Empty() ||
  1154  		!toplevel.ReadOptionalASN1(&permitted, &havePermitted, cryptobyte_asn1.Tag(0).ContextSpecific().Constructed()) ||
  1155  		!toplevel.ReadOptionalASN1(&excluded, &haveExcluded, cryptobyte_asn1.Tag(1).ContextSpecific().Constructed()) ||
  1156  		!toplevel.Empty() {
  1157  		return false, errors.New("x509: invalid NameConstraints extension")
  1158  	}
  1159  
  1160  	if !havePermitted && !haveExcluded || len(permitted) == 0 && len(excluded) == 0 {
  1161  		// From RFC 5280, Section 4.2.1.10:
  1162  		//   “either the permittedSubtrees field
  1163  		//   or the excludedSubtrees MUST be
  1164  		//   present”
  1165  		return false, errors.New("x509: empty name constraints extension")
  1166  	}
  1167  
  1168  	getValues := func(subtrees cryptobyte.String) (dnsNames []string, ips []*net.IPNet, emails, uriDomains []string, err error) {
  1169  		for !subtrees.Empty() {
  1170  			var seq, value cryptobyte.String
  1171  			var tag cryptobyte_asn1.Tag
  1172  			if !subtrees.ReadASN1(&seq, cryptobyte_asn1.SEQUENCE) ||
  1173  				!seq.ReadAnyASN1(&value, &tag) {
  1174  				return nil, nil, nil, nil, fmt.Errorf("x509: invalid NameConstraints extension")
  1175  			}
  1176  
  1177  			var (
  1178  				dnsTag   = cryptobyte_asn1.Tag(2).ContextSpecific()
  1179  				emailTag = cryptobyte_asn1.Tag(1).ContextSpecific()
  1180  				ipTag    = cryptobyte_asn1.Tag(7).ContextSpecific()
  1181  				uriTag   = cryptobyte_asn1.Tag(6).ContextSpecific()
  1182  			)
  1183  
  1184  			switch tag {
  1185  			case dnsTag:
  1186  				domain := string(value)
  1187  				if err := isIA5String(domain); err != nil {
  1188  					return nil, nil, nil, nil, errors.New("x509: invalid constraint value: " + err.Error())
  1189  				}
  1190  
  1191  				trimmedDomain := domain
  1192  				if len(trimmedDomain) > 0 && trimmedDomain[0] == '.' {
  1193  					// constraints can have a leading
  1194  					// period to exclude the domain
  1195  					// itself, but that's not valid in a
  1196  					// normal domain name.
  1197  					trimmedDomain = trimmedDomain[1:]
  1198  				}
  1199  				if _, ok := domainToReverseLabels(trimmedDomain); !ok {
  1200  					return nil, nil, nil, nil, fmt.Errorf("x509: failed to parse dnsName constraint %q", domain)
  1201  				}
  1202  				dnsNames = append(dnsNames, domain)
  1203  
  1204  			case ipTag:
  1205  				l := len(value)
  1206  				var ip, mask []byte
  1207  
  1208  				switch l {
  1209  				case 8:
  1210  					ip = value[:4]
  1211  					mask = value[4:]
  1212  
  1213  				case 32:
  1214  					ip = value[:16]
  1215  					mask = value[16:]
  1216  
  1217  				default:
  1218  					return nil, nil, nil, nil, fmt.Errorf("x509: IP constraint contained value of length %d", l)
  1219  				}
  1220  
  1221  				if !isValidIPMask(mask) {
  1222  					return nil, nil, nil, nil, fmt.Errorf("x509: IP constraint contained invalid mask %x", mask)
  1223  				}
  1224  
  1225  				ips = append(ips, &net.IPNet{IP: net.IP(ip), Mask: net.IPMask(mask)})
  1226  
  1227  			case emailTag:
  1228  				constraint := string(value)
  1229  				if err := isIA5String(constraint); err != nil {
  1230  					return nil, nil, nil, nil, errors.New("x509: invalid constraint value: " + err.Error())
  1231  				}
  1232  
  1233  				// If the constraint contains an @ then
  1234  				// it specifies an exact mailbox name.
  1235  				if strings.Contains(constraint, "@") {
  1236  					if _, ok := parseRFC2821Mailbox(constraint); !ok {
  1237  						return nil, nil, nil, nil, fmt.Errorf("x509: failed to parse rfc822Name constraint %q", constraint)
  1238  					}
  1239  				} else {
  1240  					// Otherwise it's a domain name.
  1241  					domain := constraint
  1242  					if len(domain) > 0 && domain[0] == '.' {
  1243  						domain = domain[1:]
  1244  					}
  1245  					if _, ok := domainToReverseLabels(domain); !ok {
  1246  						return nil, nil, nil, nil, fmt.Errorf("x509: failed to parse rfc822Name constraint %q", constraint)
  1247  					}
  1248  				}
  1249  				emails = append(emails, constraint)
  1250  
  1251  			case uriTag:
  1252  				domain := string(value)
  1253  				if err := isIA5String(domain); err != nil {
  1254  					return nil, nil, nil, nil, errors.New("x509: invalid constraint value: " + err.Error())
  1255  				}
  1256  
  1257  				if net.ParseIP(domain) != nil {
  1258  					return nil, nil, nil, nil, fmt.Errorf("x509: failed to parse URI constraint %q: cannot be IP address", domain)
  1259  				}
  1260  
  1261  				trimmedDomain := domain
  1262  				if len(trimmedDomain) > 0 && trimmedDomain[0] == '.' {
  1263  					// constraints can have a leading
  1264  					// period to exclude the domain itself,
  1265  					// but that's not valid in a normal
  1266  					// domain name.
  1267  					trimmedDomain = trimmedDomain[1:]
  1268  				}
  1269  				if _, ok := domainToReverseLabels(trimmedDomain); !ok {
  1270  					return nil, nil, nil, nil, fmt.Errorf("x509: failed to parse URI constraint %q", domain)
  1271  				}
  1272  				uriDomains = append(uriDomains, domain)
  1273  
  1274  			default:
  1275  				unhandled = true
  1276  			}
  1277  		}
  1278  
  1279  		return dnsNames, ips, emails, uriDomains, nil
  1280  	}
  1281  
  1282  	if out.PermittedDNSDomains, out.PermittedIPRanges, out.PermittedEmailAddresses, out.PermittedURIDomains, err = getValues(permitted); err != nil {
  1283  		return false, err
  1284  	}
  1285  	if out.ExcludedDNSDomains, out.ExcludedIPRanges, out.ExcludedEmailAddresses, out.ExcludedURIDomains, err = getValues(excluded); err != nil {
  1286  		return false, err
  1287  	}
  1288  	out.PermittedDNSDomainsCritical = e.Critical
  1289  
  1290  	return unhandled, nil
  1291  }
  1292  
  1293  func parseCertificate(in *certificate) (*Certificate, error) {
  1294  	out := new(Certificate)
  1295  	out.Raw = in.Raw
  1296  	out.RawTBSCertificate = in.TBSCertificate.Raw
  1297  	out.RawSubjectPublicKeyInfo = in.TBSCertificate.PublicKey.Raw
  1298  	out.RawSubject = in.TBSCertificate.Subject.FullBytes
  1299  	out.RawIssuer = in.TBSCertificate.Issuer.FullBytes
  1300  
  1301  	out.Signature = in.SignatureValue.RightAlign()
  1302  	out.SignatureAlgorithm =
  1303  		getSignatureAlgorithmFromAI(in.TBSCertificate.SignatureAlgorithm)
  1304  
  1305  	out.PublicKeyAlgorithm =
  1306  		getPublicKeyAlgorithmFromOID(in.TBSCertificate.PublicKey.Algorithm.Algorithm)
  1307  	var err error
  1308  	out.PublicKey, err = parsePublicKey(out.PublicKeyAlgorithm, &in.TBSCertificate.PublicKey)
  1309  	if err != nil {
  1310  		return nil, err
  1311  	}
  1312  
  1313  	out.Version = in.TBSCertificate.Version + 1
  1314  	out.SerialNumber = in.TBSCertificate.SerialNumber
  1315  
  1316  	var issuer, subject pkix.RDNSequence
  1317  	if rest, err := asn1.Unmarshal(in.TBSCertificate.Subject.FullBytes, &subject); err != nil {
  1318  		return nil, err
  1319  	} else if len(rest) != 0 {
  1320  		return nil, errors.New("x509: trailing data after X.509 subject")
  1321  	}
  1322  	if rest, err := asn1.Unmarshal(in.TBSCertificate.Issuer.FullBytes, &issuer); err != nil {
  1323  		return nil, err
  1324  	} else if len(rest) != 0 {
  1325  		return nil, errors.New("x509: trailing data after X.509 issuer")
  1326  	}
  1327  
  1328  	out.Issuer.FillFromRDNSequence(&issuer)
  1329  	out.Subject.FillFromRDNSequence(&subject)
  1330  
  1331  	out.NotBefore = in.TBSCertificate.Validity.NotBefore
  1332  	out.NotAfter = in.TBSCertificate.Validity.NotAfter
  1333  
  1334  	for _, e := range in.TBSCertificate.Extensions {
  1335  		out.Extensions = append(out.Extensions, e)
  1336  		unhandled := false
  1337  
  1338  		if len(e.Id) == 4 && e.Id[0] == 2 && e.Id[1] == 5 && e.Id[2] == 29 {
  1339  			switch e.Id[3] {
  1340  			case 15:
  1341  				out.KeyUsage, err = parseKeyUsageExtension(e.Value)
  1342  				if err != nil {
  1343  					return nil, err
  1344  				}
  1345  			case 19:
  1346  				out.IsCA, out.MaxPathLen, err = parseBasicConstraintsExtension(e.Value)
  1347  				if err != nil {
  1348  					return nil, err
  1349  				}
  1350  				out.BasicConstraintsValid = true
  1351  				out.MaxPathLenZero = out.MaxPathLen == 0
  1352  			case 17:
  1353  				out.DNSNames, out.EmailAddresses, out.IPAddresses, out.URIs, err = parseSANExtension(e.Value)
  1354  				if err != nil {
  1355  					return nil, err
  1356  				}
  1357  
  1358  				if len(out.DNSNames) == 0 && len(out.EmailAddresses) == 0 && len(out.IPAddresses) == 0 && len(out.URIs) == 0 {
  1359  					// If we didn't parse anything then we do the critical check, below.
  1360  					unhandled = true
  1361  				}
  1362  
  1363  			case 30:
  1364  				unhandled, err = parseNameConstraintsExtension(out, e)
  1365  				if err != nil {
  1366  					return nil, err
  1367  				}
  1368  
  1369  			case 31:
  1370  				// RFC 5280, 4.2.1.13
  1371  
  1372  				// CRLDistributionPoints ::= SEQUENCE SIZE (1..MAX) OF DistributionPoint
  1373  				//
  1374  				// DistributionPoint ::= SEQUENCE {
  1375  				//     distributionPoint       [0]     DistributionPointName OPTIONAL,
  1376  				//     reasons                 [1]     ReasonFlags OPTIONAL,
  1377  				//     cRLIssuer               [2]     GeneralNames OPTIONAL }
  1378  				//
  1379  				// DistributionPointName ::= CHOICE {
  1380  				//     fullName                [0]     GeneralNames,
  1381  				//     nameRelativeToCRLIssuer [1]     RelativeDistinguishedName }
  1382  
  1383  				var cdp []distributionPoint
  1384  				if rest, err := asn1.Unmarshal(e.Value, &cdp); err != nil {
  1385  					return nil, err
  1386  				} else if len(rest) != 0 {
  1387  					return nil, errors.New("x509: trailing data after X.509 CRL distribution point")
  1388  				}
  1389  
  1390  				for _, dp := range cdp {
  1391  					// Per RFC 5280, 4.2.1.13, one of distributionPoint or cRLIssuer may be empty.
  1392  					if len(dp.DistributionPoint.FullName) == 0 {
  1393  						continue
  1394  					}
  1395  
  1396  					for _, fullName := range dp.DistributionPoint.FullName {
  1397  						if fullName.Tag == 6 {
  1398  							out.CRLDistributionPoints = append(out.CRLDistributionPoints, string(fullName.Bytes))
  1399  						}
  1400  					}
  1401  				}
  1402  
  1403  			case 35:
  1404  				// RFC 5280, 4.2.1.1
  1405  				var a authKeyId
  1406  				if rest, err := asn1.Unmarshal(e.Value, &a); err != nil {
  1407  					return nil, err
  1408  				} else if len(rest) != 0 {
  1409  					return nil, errors.New("x509: trailing data after X.509 authority key-id")
  1410  				}
  1411  				out.AuthorityKeyId = a.Id
  1412  
  1413  			case 37:
  1414  				out.ExtKeyUsage, out.UnknownExtKeyUsage, err = parseExtKeyUsageExtension(e.Value)
  1415  				if err != nil {
  1416  					return nil, err
  1417  				}
  1418  			case 14:
  1419  				out.SubjectKeyId, err = parseSubjectKeyIdExtension(e.Value)
  1420  				if err != nil {
  1421  					return nil, err
  1422  				}
  1423  			case 32:
  1424  				out.PolicyIdentifiers, err = parseCertificatePoliciesExtension(e.Value)
  1425  				if err != nil {
  1426  					return nil, err
  1427  				}
  1428  			default:
  1429  				// Unknown extensions are recorded if critical.
  1430  				unhandled = true
  1431  			}
  1432  		} else if e.Id.Equal(oidExtensionAuthorityInfoAccess) {
  1433  			// RFC 5280 4.2.2.1: Authority Information Access
  1434  			var aia []authorityInfoAccess
  1435  			if rest, err := asn1.Unmarshal(e.Value, &aia); err != nil {
  1436  				return nil, err
  1437  			} else if len(rest) != 0 {
  1438  				return nil, errors.New("x509: trailing data after X.509 authority information")
  1439  			}
  1440  
  1441  			for _, v := range aia {
  1442  				// GeneralName: uniformResourceIdentifier [6] IA5String
  1443  				if v.Location.Tag != 6 {
  1444  					continue
  1445  				}
  1446  				if v.Method.Equal(oidAuthorityInfoAccessOcsp) {
  1447  					out.OCSPServer = append(out.OCSPServer, string(v.Location.Bytes))
  1448  				} else if v.Method.Equal(oidAuthorityInfoAccessIssuers) {
  1449  					out.IssuingCertificateURL = append(out.IssuingCertificateURL, string(v.Location.Bytes))
  1450  				}
  1451  			}
  1452  		} else {
  1453  			// Unknown extensions are recorded if critical.
  1454  			unhandled = true
  1455  		}
  1456  
  1457  		if e.Critical && unhandled {
  1458  			out.UnhandledCriticalExtensions = append(out.UnhandledCriticalExtensions, e.Id)
  1459  		}
  1460  	}
  1461  
  1462  	return out, nil
  1463  }
  1464  
  1465  // parseKeyUsageExtension parses id-ce-keyUsage (2.5.29.15) from RFC 5280
  1466  // Section 4.2.1.3
  1467  func parseKeyUsageExtension(ext []byte) (KeyUsage, error) {
  1468  	var usageBits asn1.BitString
  1469  	if rest, err := asn1.Unmarshal(ext, &usageBits); err != nil {
  1470  		return 0, err
  1471  	} else if len(rest) != 0 {
  1472  		return 0, errors.New("x509: trailing data after X.509 KeyUsage")
  1473  	}
  1474  
  1475  	var usage int
  1476  	for i := 0; i < 9; i++ {
  1477  		if usageBits.At(i) != 0 {
  1478  			usage |= 1 << uint(i)
  1479  		}
  1480  	}
  1481  	return KeyUsage(usage), nil
  1482  }
  1483  
  1484  // parseBasicConstraintsExtension parses id-ce-basicConstraints (2.5.29.19)
  1485  // from RFC 5280 Section 4.2.1.9
  1486  func parseBasicConstraintsExtension(ext []byte) (isCA bool, maxPathLen int, err error) {
  1487  	var constraints basicConstraints
  1488  	if rest, err := asn1.Unmarshal(ext, &constraints); err != nil {
  1489  		return false, 0, err
  1490  	} else if len(rest) != 0 {
  1491  		return false, 0, errors.New("x509: trailing data after X.509 BasicConstraints")
  1492  	}
  1493  
  1494  	// TODO: map out.MaxPathLen to 0 if it has the -1 default value? (Issue 19285)
  1495  	return constraints.IsCA, constraints.MaxPathLen, nil
  1496  }
  1497  
  1498  // parseExtKeyUsageExtension parses id-ce-extKeyUsage (2.5.29.37) from
  1499  // RFC 5280 Section 4.2.1.12
  1500  func parseExtKeyUsageExtension(ext []byte) ([]ExtKeyUsage, []asn1.ObjectIdentifier, error) {
  1501  	var keyUsage []asn1.ObjectIdentifier
  1502  	if rest, err := asn1.Unmarshal(ext, &keyUsage); err != nil {
  1503  		return nil, nil, err
  1504  	} else if len(rest) != 0 {
  1505  		return nil, nil, errors.New("x509: trailing data after X.509 ExtendedKeyUsage")
  1506  	}
  1507  
  1508  	var extKeyUsages []ExtKeyUsage
  1509  	var unknownUsages []asn1.ObjectIdentifier
  1510  	for _, u := range keyUsage {
  1511  		if extKeyUsage, ok := extKeyUsageFromOID(u); ok {
  1512  			extKeyUsages = append(extKeyUsages, extKeyUsage)
  1513  		} else {
  1514  			unknownUsages = append(unknownUsages, u)
  1515  		}
  1516  	}
  1517  	return extKeyUsages, unknownUsages, nil
  1518  }
  1519  
  1520  // parseSubjectKeyIdExtension parses id-ce-subjectKeyIdentifier (2.5.29.14)
  1521  // from RFC 5280 Section 4.2.1.2
  1522  func parseSubjectKeyIdExtension(ext []byte) ([]byte, error) {
  1523  	var keyid []byte
  1524  	if rest, err := asn1.Unmarshal(ext, &keyid); err != nil {
  1525  		return nil, err
  1526  	} else if len(rest) != 0 {
  1527  		return nil, errors.New("x509: trailing data after X.509 key-id")
  1528  	}
  1529  	return keyid, nil
  1530  }
  1531  
  1532  func parseCertificatePoliciesExtension(ext []byte) ([]asn1.ObjectIdentifier, error) {
  1533  	var policies []policyInformation
  1534  	if rest, err := asn1.Unmarshal(ext, &policies); err != nil {
  1535  		return nil, err
  1536  	} else if len(rest) != 0 {
  1537  		return nil, errors.New("x509: trailing data after X.509 certificate policies")
  1538  	}
  1539  	oids := make([]asn1.ObjectIdentifier, len(policies))
  1540  	for i, policy := range policies {
  1541  		oids[i] = policy.Policy
  1542  	}
  1543  	return oids, nil
  1544  }
  1545  
  1546  // ParseCertificate parses a single certificate from the given ASN.1 DER data.
  1547  func ParseCertificate(asn1Data []byte) (*Certificate, error) {
  1548  	var cert certificate
  1549  	rest, err := asn1.Unmarshal(asn1Data, &cert)
  1550  	if err != nil {
  1551  		return nil, err
  1552  	}
  1553  	if len(rest) > 0 {
  1554  		return nil, asn1.SyntaxError{Msg: "trailing data"}
  1555  	}
  1556  
  1557  	return parseCertificate(&cert)
  1558  }
  1559  
  1560  // ParseCertificates parses one or more certificates from the given ASN.1 DER
  1561  // data. The certificates must be concatenated with no intermediate padding.
  1562  func ParseCertificates(asn1Data []byte) ([]*Certificate, error) {
  1563  	var v []*certificate
  1564  
  1565  	for len(asn1Data) > 0 {
  1566  		cert := new(certificate)
  1567  		var err error
  1568  		asn1Data, err = asn1.Unmarshal(asn1Data, cert)
  1569  		if err != nil {
  1570  			return nil, err
  1571  		}
  1572  		v = append(v, cert)
  1573  	}
  1574  
  1575  	ret := make([]*Certificate, len(v))
  1576  	for i, ci := range v {
  1577  		cert, err := parseCertificate(ci)
  1578  		if err != nil {
  1579  			return nil, err
  1580  		}
  1581  		ret[i] = cert
  1582  	}
  1583  
  1584  	return ret, nil
  1585  }
  1586  
  1587  func reverseBitsInAByte(in byte) byte {
  1588  	b1 := in>>4 | in<<4
  1589  	b2 := b1>>2&0x33 | b1<<2&0xcc
  1590  	b3 := b2>>1&0x55 | b2<<1&0xaa
  1591  	return b3
  1592  }
  1593  
  1594  // asn1BitLength returns the bit-length of bitString by considering the
  1595  // most-significant bit in a byte to be the "first" bit. This convention
  1596  // matches ASN.1, but differs from almost everything else.
  1597  func asn1BitLength(bitString []byte) int {
  1598  	bitLen := len(bitString) * 8
  1599  
  1600  	for i := range bitString {
  1601  		b := bitString[len(bitString)-i-1]
  1602  
  1603  		for bit := uint(0); bit < 8; bit++ {
  1604  			if (b>>bit)&1 == 1 {
  1605  				return bitLen
  1606  			}
  1607  			bitLen--
  1608  		}
  1609  	}
  1610  
  1611  	return 0
  1612  }
  1613  
  1614  var (
  1615  	oidExtensionSubjectKeyId          = []int{2, 5, 29, 14}
  1616  	oidExtensionKeyUsage              = []int{2, 5, 29, 15}
  1617  	oidExtensionExtendedKeyUsage      = []int{2, 5, 29, 37}
  1618  	oidExtensionAuthorityKeyId        = []int{2, 5, 29, 35}
  1619  	oidExtensionBasicConstraints      = []int{2, 5, 29, 19}
  1620  	oidExtensionSubjectAltName        = []int{2, 5, 29, 17}
  1621  	oidExtensionCertificatePolicies   = []int{2, 5, 29, 32}
  1622  	oidExtensionNameConstraints       = []int{2, 5, 29, 30}
  1623  	oidExtensionCRLDistributionPoints = []int{2, 5, 29, 31}
  1624  	oidExtensionAuthorityInfoAccess   = []int{1, 3, 6, 1, 5, 5, 7, 1, 1}
  1625  	oidExtensionCRLNumber             = []int{2, 5, 29, 20}
  1626  )
  1627  
  1628  var (
  1629  	oidAuthorityInfoAccessOcsp    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 48, 1}
  1630  	oidAuthorityInfoAccessIssuers = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 48, 2}
  1631  )
  1632  
  1633  // oidNotInExtensions reports whether an extension with the given oid exists in
  1634  // extensions.
  1635  func oidInExtensions(oid asn1.ObjectIdentifier, extensions []pkix.Extension) bool {
  1636  	for _, e := range extensions {
  1637  		if e.Id.Equal(oid) {
  1638  			return true
  1639  		}
  1640  	}
  1641  	return false
  1642  }
  1643  
  1644  // marshalSANs marshals a list of addresses into a the contents of an X.509
  1645  // SubjectAlternativeName extension.
  1646  func marshalSANs(dnsNames, emailAddresses []string, ipAddresses []net.IP, uris []*url.URL) (derBytes []byte, err error) {
  1647  	var rawValues []asn1.RawValue
  1648  	for _, name := range dnsNames {
  1649  		if err := isIA5String(name); err != nil {
  1650  			return nil, err
  1651  		}
  1652  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeDNS, Class: 2, Bytes: []byte(name)})
  1653  	}
  1654  	for _, email := range emailAddresses {
  1655  		if err := isIA5String(email); err != nil {
  1656  			return nil, err
  1657  		}
  1658  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeEmail, Class: 2, Bytes: []byte(email)})
  1659  	}
  1660  	for _, rawIP := range ipAddresses {
  1661  		// If possible, we always want to encode IPv4 addresses in 4 bytes.
  1662  		ip := rawIP.To4()
  1663  		if ip == nil {
  1664  			ip = rawIP
  1665  		}
  1666  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeIP, Class: 2, Bytes: ip})
  1667  	}
  1668  	for _, uri := range uris {
  1669  		uriStr := uri.String()
  1670  		if err := isIA5String(uriStr); err != nil {
  1671  			return nil, err
  1672  		}
  1673  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeURI, Class: 2, Bytes: []byte(uriStr)})
  1674  	}
  1675  	return asn1.Marshal(rawValues)
  1676  }
  1677  
  1678  func isIA5String(s string) error {
  1679  	for _, r := range s {
  1680  		// Per RFC5280 "IA5String is limited to the set of ASCII characters"
  1681  		if r > unicode.MaxASCII {
  1682  			return fmt.Errorf("x509: %q cannot be encoded as an IA5String", s)
  1683  		}
  1684  	}
  1685  
  1686  	return nil
  1687  }
  1688  
  1689  func buildCertExtensions(template *Certificate, subjectIsEmpty bool, authorityKeyId []byte, subjectKeyId []byte) (ret []pkix.Extension, err error) {
  1690  	ret = make([]pkix.Extension, 10 /* maximum number of elements. */)
  1691  	n := 0
  1692  
  1693  	if template.KeyUsage != 0 &&
  1694  		!oidInExtensions(oidExtensionKeyUsage, template.ExtraExtensions) {
  1695  		ret[n], err = marshalKeyUsage(template.KeyUsage)
  1696  		if err != nil {
  1697  			return nil, err
  1698  		}
  1699  		n++
  1700  	}
  1701  
  1702  	if (len(template.ExtKeyUsage) > 0 || len(template.UnknownExtKeyUsage) > 0) &&
  1703  		!oidInExtensions(oidExtensionExtendedKeyUsage, template.ExtraExtensions) {
  1704  		ret[n], err = marshalExtKeyUsage(template.ExtKeyUsage, template.UnknownExtKeyUsage)
  1705  		if err != nil {
  1706  			return nil, err
  1707  		}
  1708  		n++
  1709  	}
  1710  
  1711  	if template.BasicConstraintsValid && !oidInExtensions(oidExtensionBasicConstraints, template.ExtraExtensions) {
  1712  		ret[n], err = marshalBasicConstraints(template.IsCA, template.MaxPathLen, template.MaxPathLenZero)
  1713  		if err != nil {
  1714  			return nil, err
  1715  		}
  1716  		n++
  1717  	}
  1718  
  1719  	if len(subjectKeyId) > 0 && !oidInExtensions(oidExtensionSubjectKeyId, template.ExtraExtensions) {
  1720  		ret[n].Id = oidExtensionSubjectKeyId
  1721  		ret[n].Value, err = asn1.Marshal(subjectKeyId)
  1722  		if err != nil {
  1723  			return
  1724  		}
  1725  		n++
  1726  	}
  1727  
  1728  	if len(authorityKeyId) > 0 && !oidInExtensions(oidExtensionAuthorityKeyId, template.ExtraExtensions) {
  1729  		ret[n].Id = oidExtensionAuthorityKeyId
  1730  		ret[n].Value, err = asn1.Marshal(authKeyId{authorityKeyId})
  1731  		if err != nil {
  1732  			return
  1733  		}
  1734  		n++
  1735  	}
  1736  
  1737  	if (len(template.OCSPServer) > 0 || len(template.IssuingCertificateURL) > 0) &&
  1738  		!oidInExtensions(oidExtensionAuthorityInfoAccess, template.ExtraExtensions) {
  1739  		ret[n].Id = oidExtensionAuthorityInfoAccess
  1740  		var aiaValues []authorityInfoAccess
  1741  		for _, name := range template.OCSPServer {
  1742  			aiaValues = append(aiaValues, authorityInfoAccess{
  1743  				Method:   oidAuthorityInfoAccessOcsp,
  1744  				Location: asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)},
  1745  			})
  1746  		}
  1747  		for _, name := range template.IssuingCertificateURL {
  1748  			aiaValues = append(aiaValues, authorityInfoAccess{
  1749  				Method:   oidAuthorityInfoAccessIssuers,
  1750  				Location: asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)},
  1751  			})
  1752  		}
  1753  		ret[n].Value, err = asn1.Marshal(aiaValues)
  1754  		if err != nil {
  1755  			return
  1756  		}
  1757  		n++
  1758  	}
  1759  
  1760  	if (len(template.DNSNames) > 0 || len(template.EmailAddresses) > 0 || len(template.IPAddresses) > 0 || len(template.URIs) > 0) &&
  1761  		!oidInExtensions(oidExtensionSubjectAltName, template.ExtraExtensions) {
  1762  		ret[n].Id = oidExtensionSubjectAltName
  1763  		// From RFC 5280, Section 4.2.1.6:
  1764  		// “If the subject field contains an empty sequence ... then
  1765  		// subjectAltName extension ... is marked as critical”
  1766  		ret[n].Critical = subjectIsEmpty
  1767  		ret[n].Value, err = marshalSANs(template.DNSNames, template.EmailAddresses, template.IPAddresses, template.URIs)
  1768  		if err != nil {
  1769  			return
  1770  		}
  1771  		n++
  1772  	}
  1773  
  1774  	if len(template.PolicyIdentifiers) > 0 &&
  1775  		!oidInExtensions(oidExtensionCertificatePolicies, template.ExtraExtensions) {
  1776  		ret[n], err = marshalCertificatePolicies(template.PolicyIdentifiers)
  1777  		if err != nil {
  1778  			return nil, err
  1779  		}
  1780  		n++
  1781  	}
  1782  
  1783  	if (len(template.PermittedDNSDomains) > 0 || len(template.ExcludedDNSDomains) > 0 ||
  1784  		len(template.PermittedIPRanges) > 0 || len(template.ExcludedIPRanges) > 0 ||
  1785  		len(template.PermittedEmailAddresses) > 0 || len(template.ExcludedEmailAddresses) > 0 ||
  1786  		len(template.PermittedURIDomains) > 0 || len(template.ExcludedURIDomains) > 0) &&
  1787  		!oidInExtensions(oidExtensionNameConstraints, template.ExtraExtensions) {
  1788  		ret[n].Id = oidExtensionNameConstraints
  1789  		ret[n].Critical = template.PermittedDNSDomainsCritical
  1790  
  1791  		ipAndMask := func(ipNet *net.IPNet) []byte {
  1792  			maskedIP := ipNet.IP.Mask(ipNet.Mask)
  1793  			ipAndMask := make([]byte, 0, len(maskedIP)+len(ipNet.Mask))
  1794  			ipAndMask = append(ipAndMask, maskedIP...)
  1795  			ipAndMask = append(ipAndMask, ipNet.Mask...)
  1796  			return ipAndMask
  1797  		}
  1798  
  1799  		serialiseConstraints := func(dns []string, ips []*net.IPNet, emails []string, uriDomains []string) (der []byte, err error) {
  1800  			var b cryptobyte.Builder
  1801  
  1802  			for _, name := range dns {
  1803  				if err = isIA5String(name); err != nil {
  1804  					return nil, err
  1805  				}
  1806  
  1807  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1808  					b.AddASN1(cryptobyte_asn1.Tag(2).ContextSpecific(), func(b *cryptobyte.Builder) {
  1809  						b.AddBytes([]byte(name))
  1810  					})
  1811  				})
  1812  			}
  1813  
  1814  			for _, ipNet := range ips {
  1815  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1816  					b.AddASN1(cryptobyte_asn1.Tag(7).ContextSpecific(), func(b *cryptobyte.Builder) {
  1817  						b.AddBytes(ipAndMask(ipNet))
  1818  					})
  1819  				})
  1820  			}
  1821  
  1822  			for _, email := range emails {
  1823  				if err = isIA5String(email); err != nil {
  1824  					return nil, err
  1825  				}
  1826  
  1827  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1828  					b.AddASN1(cryptobyte_asn1.Tag(1).ContextSpecific(), func(b *cryptobyte.Builder) {
  1829  						b.AddBytes([]byte(email))
  1830  					})
  1831  				})
  1832  			}
  1833  
  1834  			for _, uriDomain := range uriDomains {
  1835  				if err = isIA5String(uriDomain); err != nil {
  1836  					return nil, err
  1837  				}
  1838  
  1839  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1840  					b.AddASN1(cryptobyte_asn1.Tag(6).ContextSpecific(), func(b *cryptobyte.Builder) {
  1841  						b.AddBytes([]byte(uriDomain))
  1842  					})
  1843  				})
  1844  			}
  1845  
  1846  			return b.Bytes()
  1847  		}
  1848  
  1849  		permitted, err := serialiseConstraints(template.PermittedDNSDomains, template.PermittedIPRanges, template.PermittedEmailAddresses, template.PermittedURIDomains)
  1850  		if err != nil {
  1851  			return nil, err
  1852  		}
  1853  
  1854  		excluded, err := serialiseConstraints(template.ExcludedDNSDomains, template.ExcludedIPRanges, template.ExcludedEmailAddresses, template.ExcludedURIDomains)
  1855  		if err != nil {
  1856  			return nil, err
  1857  		}
  1858  
  1859  		var b cryptobyte.Builder
  1860  		b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1861  			if len(permitted) > 0 {
  1862  				b.AddASN1(cryptobyte_asn1.Tag(0).ContextSpecific().Constructed(), func(b *cryptobyte.Builder) {
  1863  					b.AddBytes(permitted)
  1864  				})
  1865  			}
  1866  
  1867  			if len(excluded) > 0 {
  1868  				b.AddASN1(cryptobyte_asn1.Tag(1).ContextSpecific().Constructed(), func(b *cryptobyte.Builder) {
  1869  					b.AddBytes(excluded)
  1870  				})
  1871  			}
  1872  		})
  1873  
  1874  		ret[n].Value, err = b.Bytes()
  1875  		if err != nil {
  1876  			return nil, err
  1877  		}
  1878  		n++
  1879  	}
  1880  
  1881  	if len(template.CRLDistributionPoints) > 0 &&
  1882  		!oidInExtensions(oidExtensionCRLDistributionPoints, template.ExtraExtensions) {
  1883  		ret[n].Id = oidExtensionCRLDistributionPoints
  1884  
  1885  		var crlDp []distributionPoint
  1886  		for _, name := range template.CRLDistributionPoints {
  1887  			dp := distributionPoint{
  1888  				DistributionPoint: distributionPointName{
  1889  					FullName: []asn1.RawValue{
  1890  						{Tag: 6, Class: 2, Bytes: []byte(name)},
  1891  					},
  1892  				},
  1893  			}
  1894  			crlDp = append(crlDp, dp)
  1895  		}
  1896  
  1897  		ret[n].Value, err = asn1.Marshal(crlDp)
  1898  		if err != nil {
  1899  			return
  1900  		}
  1901  		n++
  1902  	}
  1903  
  1904  	// Adding another extension here? Remember to update the maximum number
  1905  	// of elements in the make() at the top of the function and the list of
  1906  	// template fields used in CreateCertificate documentation.
  1907  
  1908  	return append(ret[:n], template.ExtraExtensions...), nil
  1909  }
  1910  
  1911  func marshalKeyUsage(ku KeyUsage) (pkix.Extension, error) {
  1912  	ext := pkix.Extension{Id: oidExtensionKeyUsage, Critical: true}
  1913  
  1914  	var a [2]byte
  1915  	a[0] = reverseBitsInAByte(byte(ku))
  1916  	a[1] = reverseBitsInAByte(byte(ku >> 8))
  1917  
  1918  	l := 1
  1919  	if a[1] != 0 {
  1920  		l = 2
  1921  	}
  1922  
  1923  	bitString := a[:l]
  1924  	var err error
  1925  	ext.Value, err = asn1.Marshal(asn1.BitString{Bytes: bitString, BitLength: asn1BitLength(bitString)})
  1926  	if err != nil {
  1927  		return ext, err
  1928  	}
  1929  	return ext, nil
  1930  }
  1931  
  1932  func marshalExtKeyUsage(extUsages []ExtKeyUsage, unknownUsages []asn1.ObjectIdentifier) (pkix.Extension, error) {
  1933  	ext := pkix.Extension{Id: oidExtensionExtendedKeyUsage}
  1934  
  1935  	oids := make([]asn1.ObjectIdentifier, len(extUsages)+len(unknownUsages))
  1936  	for i, u := range extUsages {
  1937  		if oid, ok := oidFromExtKeyUsage(u); ok {
  1938  			oids[i] = oid
  1939  		} else {
  1940  			return ext, errors.New("x509: unknown extended key usage")
  1941  		}
  1942  	}
  1943  
  1944  	copy(oids[len(extUsages):], unknownUsages)
  1945  
  1946  	var err error
  1947  	ext.Value, err = asn1.Marshal(oids)
  1948  	if err != nil {
  1949  		return ext, err
  1950  	}
  1951  	return ext, nil
  1952  }
  1953  
  1954  func marshalBasicConstraints(isCA bool, maxPathLen int, maxPathLenZero bool) (pkix.Extension, error) {
  1955  	ext := pkix.Extension{Id: oidExtensionBasicConstraints, Critical: true}
  1956  	// Leaving MaxPathLen as zero indicates that no maximum path
  1957  	// length is desired, unless MaxPathLenZero is set. A value of
  1958  	// -1 causes encoding/asn1 to omit the value as desired.
  1959  	if maxPathLen == 0 && !maxPathLenZero {
  1960  		maxPathLen = -1
  1961  	}
  1962  	var err error
  1963  	ext.Value, err = asn1.Marshal(basicConstraints{isCA, maxPathLen})
  1964  	if err != nil {
  1965  		return ext, nil
  1966  	}
  1967  	return ext, nil
  1968  }
  1969  
  1970  func marshalCertificatePolicies(policyIdentifiers []asn1.ObjectIdentifier) (pkix.Extension, error) {
  1971  	ext := pkix.Extension{Id: oidExtensionCertificatePolicies}
  1972  	policies := make([]policyInformation, len(policyIdentifiers))
  1973  	for i, policy := range policyIdentifiers {
  1974  		policies[i].Policy = policy
  1975  	}
  1976  	var err error
  1977  	ext.Value, err = asn1.Marshal(policies)
  1978  	if err != nil {
  1979  		return ext, err
  1980  	}
  1981  	return ext, nil
  1982  }
  1983  
  1984  func buildCSRExtensions(template *CertificateRequest) ([]pkix.Extension, error) {
  1985  	var ret []pkix.Extension
  1986  
  1987  	if (len(template.DNSNames) > 0 || len(template.EmailAddresses) > 0 || len(template.IPAddresses) > 0 || len(template.URIs) > 0) &&
  1988  		!oidInExtensions(oidExtensionSubjectAltName, template.ExtraExtensions) {
  1989  		sanBytes, err := marshalSANs(template.DNSNames, template.EmailAddresses, template.IPAddresses, template.URIs)
  1990  		if err != nil {
  1991  			return nil, err
  1992  		}
  1993  
  1994  		ret = append(ret, pkix.Extension{
  1995  			Id:    oidExtensionSubjectAltName,
  1996  			Value: sanBytes,
  1997  		})
  1998  	}
  1999  
  2000  	return append(ret, template.ExtraExtensions...), nil
  2001  }
  2002  
  2003  func subjectBytes(cert *Certificate) ([]byte, error) {
  2004  	if len(cert.RawSubject) > 0 {
  2005  		return cert.RawSubject, nil
  2006  	}
  2007  
  2008  	return asn1.Marshal(cert.Subject.ToRDNSequence())
  2009  }
  2010  
  2011  // signingParamsForPublicKey returns the parameters to use for signing with
  2012  // priv. If requestedSigAlgo is not zero then it overrides the default
  2013  // signature algorithm.
  2014  func signingParamsForPublicKey(pub interface{}, requestedSigAlgo SignatureAlgorithm) (hashFunc crypto.Hash, sigAlgo pkix.AlgorithmIdentifier, err error) {
  2015  	var pubType PublicKeyAlgorithm
  2016  
  2017  	switch pub := pub.(type) {
  2018  	case *rsa.PublicKey:
  2019  		pubType = RSA
  2020  		hashFunc = crypto.SHA256
  2021  		sigAlgo.Algorithm = oidSignatureSHA256WithRSA
  2022  		sigAlgo.Parameters = asn1.NullRawValue
  2023  
  2024  	case *ecdsa.PublicKey:
  2025  		pubType = ECDSA
  2026  
  2027  		switch pub.Curve {
  2028  		case elliptic.P224(), elliptic.P256():
  2029  			hashFunc = crypto.SHA256
  2030  			sigAlgo.Algorithm = oidSignatureECDSAWithSHA256
  2031  		case elliptic.P384():
  2032  			hashFunc = crypto.SHA384
  2033  			sigAlgo.Algorithm = oidSignatureECDSAWithSHA384
  2034  		case elliptic.P521():
  2035  			hashFunc = crypto.SHA512
  2036  			sigAlgo.Algorithm = oidSignatureECDSAWithSHA512
  2037  		default:
  2038  			err = errors.New("x509: unknown elliptic curve")
  2039  		}
  2040  
  2041  	case ed25519.PublicKey:
  2042  		pubType = Ed25519
  2043  		sigAlgo.Algorithm = oidSignatureEd25519
  2044  
  2045  	default:
  2046  		err = errors.New("x509: only RSA, ECDSA and Ed25519 keys supported")
  2047  	}
  2048  
  2049  	if err != nil {
  2050  		return
  2051  	}
  2052  
  2053  	if requestedSigAlgo == 0 {
  2054  		return
  2055  	}
  2056  
  2057  	found := false
  2058  	for _, details := range signatureAlgorithmDetails {
  2059  		if details.algo == requestedSigAlgo {
  2060  			if details.pubKeyAlgo != pubType {
  2061  				err = errors.New("x509: requested SignatureAlgorithm does not match private key type")
  2062  				return
  2063  			}
  2064  			sigAlgo.Algorithm, hashFunc = details.oid, details.hash
  2065  			if hashFunc == 0 && pubType != Ed25519 {
  2066  				err = errors.New("x509: cannot sign with hash function requested")
  2067  				return
  2068  			}
  2069  			if requestedSigAlgo.isRSAPSS() {
  2070  				sigAlgo.Parameters = hashToPSSParameters[hashFunc]
  2071  			}
  2072  			found = true
  2073  			break
  2074  		}
  2075  	}
  2076  
  2077  	if !found {
  2078  		err = errors.New("x509: unknown SignatureAlgorithm")
  2079  	}
  2080  
  2081  	return
  2082  }
  2083  
  2084  // emptyASN1Subject is the ASN.1 DER encoding of an empty Subject, which is
  2085  // just an empty SEQUENCE.
  2086  var emptyASN1Subject = []byte{0x30, 0}
  2087  
  2088  // CreateCertificate creates a new X.509v3 certificate based on a template.
  2089  // The following members of template are used:
  2090  //
  2091  //  - AuthorityKeyId
  2092  //  - BasicConstraintsValid
  2093  //  - CRLDistributionPoints
  2094  //  - DNSNames
  2095  //  - EmailAddresses
  2096  //  - ExcludedDNSDomains
  2097  //  - ExcludedEmailAddresses
  2098  //  - ExcludedIPRanges
  2099  //  - ExcludedURIDomains
  2100  //  - ExtKeyUsage
  2101  //  - ExtraExtensions
  2102  //  - IPAddresses
  2103  //  - IsCA
  2104  //  - IssuingCertificateURL
  2105  //  - KeyUsage
  2106  //  - MaxPathLen
  2107  //  - MaxPathLenZero
  2108  //  - NotAfter
  2109  //  - NotBefore
  2110  //  - OCSPServer
  2111  //  - PermittedDNSDomains
  2112  //  - PermittedDNSDomainsCritical
  2113  //  - PermittedEmailAddresses
  2114  //  - PermittedIPRanges
  2115  //  - PermittedURIDomains
  2116  //  - PolicyIdentifiers
  2117  //  - SerialNumber
  2118  //  - SignatureAlgorithm
  2119  //  - Subject
  2120  //  - SubjectKeyId
  2121  //  - URIs
  2122  //  - UnknownExtKeyUsage
  2123  //
  2124  // The certificate is signed by parent. If parent is equal to template then the
  2125  // certificate is self-signed. The parameter pub is the public key of the
  2126  // signee and priv is the private key of the signer.
  2127  //
  2128  // The returned slice is the certificate in DER encoding.
  2129  //
  2130  // The currently supported key types are *rsa.PublicKey, *ecdsa.PublicKey and
  2131  // ed25519.PublicKey. pub must be a supported key type, and priv must be a
  2132  // crypto.Signer with a supported public key.
  2133  //
  2134  // The AuthorityKeyId will be taken from the SubjectKeyId of parent, if any,
  2135  // unless the resulting certificate is self-signed. Otherwise the value from
  2136  // template will be used.
  2137  //
  2138  // If SubjectKeyId from template is empty and the template is a CA, SubjectKeyId
  2139  // will be generated from the hash of the public key.
  2140  func CreateCertificate(rand io.Reader, template, parent *Certificate, pub, priv interface{}) (cert []byte, err error) {
  2141  	key, ok := priv.(crypto.Signer)
  2142  	if !ok {
  2143  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  2144  	}
  2145  
  2146  	if template.SerialNumber == nil {
  2147  		return nil, errors.New("x509: no SerialNumber given")
  2148  	}
  2149  
  2150  	if template.BasicConstraintsValid && !template.IsCA && template.MaxPathLen != -1 && (template.MaxPathLen != 0 || template.MaxPathLenZero) {
  2151  		return nil, errors.New("x509: only CAs are allowed to specify MaxPathLen")
  2152  	}
  2153  
  2154  	hashFunc, signatureAlgorithm, err := signingParamsForPublicKey(key.Public(), template.SignatureAlgorithm)
  2155  	if err != nil {
  2156  		return nil, err
  2157  	}
  2158  
  2159  	publicKeyBytes, publicKeyAlgorithm, err := marshalPublicKey(pub)
  2160  	if err != nil {
  2161  		return nil, err
  2162  	}
  2163  
  2164  	asn1Issuer, err := subjectBytes(parent)
  2165  	if err != nil {
  2166  		return
  2167  	}
  2168  
  2169  	asn1Subject, err := subjectBytes(template)
  2170  	if err != nil {
  2171  		return
  2172  	}
  2173  
  2174  	authorityKeyId := template.AuthorityKeyId
  2175  	if !bytes.Equal(asn1Issuer, asn1Subject) && len(parent.SubjectKeyId) > 0 {
  2176  		authorityKeyId = parent.SubjectKeyId
  2177  	}
  2178  
  2179  	subjectKeyId := template.SubjectKeyId
  2180  	if len(subjectKeyId) == 0 && template.IsCA {
  2181  		// SubjectKeyId generated using method 1 in RFC 5280, Section 4.2.1.2:
  2182  		//   (1) The keyIdentifier is composed of the 160-bit SHA-1 hash of the
  2183  		//   value of the BIT STRING subjectPublicKey (excluding the tag,
  2184  		//   length, and number of unused bits).
  2185  		h := sha1.Sum(publicKeyBytes)
  2186  		subjectKeyId = h[:]
  2187  	}
  2188  
  2189  	extensions, err := buildCertExtensions(template, bytes.Equal(asn1Subject, emptyASN1Subject), authorityKeyId, subjectKeyId)
  2190  	if err != nil {
  2191  		return
  2192  	}
  2193  
  2194  	encodedPublicKey := asn1.BitString{BitLength: len(publicKeyBytes) * 8, Bytes: publicKeyBytes}
  2195  	c := tbsCertificate{
  2196  		Version:            2,
  2197  		SerialNumber:       template.SerialNumber,
  2198  		SignatureAlgorithm: signatureAlgorithm,
  2199  		Issuer:             asn1.RawValue{FullBytes: asn1Issuer},
  2200  		Validity:           validity{template.NotBefore.UTC(), template.NotAfter.UTC()},
  2201  		Subject:            asn1.RawValue{FullBytes: asn1Subject},
  2202  		PublicKey:          publicKeyInfo{nil, publicKeyAlgorithm, encodedPublicKey},
  2203  		Extensions:         extensions,
  2204  	}
  2205  
  2206  	tbsCertContents, err := asn1.Marshal(c)
  2207  	if err != nil {
  2208  		return
  2209  	}
  2210  	c.Raw = tbsCertContents
  2211  
  2212  	signed := tbsCertContents
  2213  	if hashFunc != 0 {
  2214  		h := hashFunc.New()
  2215  		h.Write(signed)
  2216  		signed = h.Sum(nil)
  2217  	}
  2218  
  2219  	var signerOpts crypto.SignerOpts = hashFunc
  2220  	if template.SignatureAlgorithm != 0 && template.SignatureAlgorithm.isRSAPSS() {
  2221  		signerOpts = &rsa.PSSOptions{
  2222  			SaltLength: rsa.PSSSaltLengthEqualsHash,
  2223  			Hash:       hashFunc,
  2224  		}
  2225  	}
  2226  
  2227  	var signature []byte
  2228  	signature, err = key.Sign(rand, signed, signerOpts)
  2229  	if err != nil {
  2230  		return
  2231  	}
  2232  
  2233  	signedCert, err := asn1.Marshal(certificate{
  2234  		nil,
  2235  		c,
  2236  		signatureAlgorithm,
  2237  		asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  2238  	})
  2239  	if err != nil {
  2240  		return nil, err
  2241  	}
  2242  
  2243  	// Check the signature to ensure the crypto.Signer behaved correctly.
  2244  	// We skip this check if the signature algorithm is MD5WithRSA as we
  2245  	// only support this algorithm for signing, and not verification.
  2246  	if sigAlg := getSignatureAlgorithmFromAI(signatureAlgorithm); sigAlg != MD5WithRSA {
  2247  		if err := checkSignature(sigAlg, c.Raw, signature, key.Public()); err != nil {
  2248  			return nil, fmt.Errorf("x509: signature over certificate returned by signer is invalid: %w", err)
  2249  		}
  2250  	}
  2251  
  2252  	return signedCert, nil
  2253  }
  2254  
  2255  // pemCRLPrefix is the magic string that indicates that we have a PEM encoded
  2256  // CRL.
  2257  var pemCRLPrefix = []byte("-----BEGIN X509 CRL")
  2258  
  2259  // pemType is the type of a PEM encoded CRL.
  2260  var pemType = "X509 CRL"
  2261  
  2262  // ParseCRL parses a CRL from the given bytes. It's often the case that PEM
  2263  // encoded CRLs will appear where they should be DER encoded, so this function
  2264  // will transparently handle PEM encoding as long as there isn't any leading
  2265  // garbage.
  2266  func ParseCRL(crlBytes []byte) (*pkix.CertificateList, error) {
  2267  	if bytes.HasPrefix(crlBytes, pemCRLPrefix) {
  2268  		block, _ := pem.Decode(crlBytes)
  2269  		if block != nil && block.Type == pemType {
  2270  			crlBytes = block.Bytes
  2271  		}
  2272  	}
  2273  	return ParseDERCRL(crlBytes)
  2274  }
  2275  
  2276  // ParseDERCRL parses a DER encoded CRL from the given bytes.
  2277  func ParseDERCRL(derBytes []byte) (*pkix.CertificateList, error) {
  2278  	certList := new(pkix.CertificateList)
  2279  	if rest, err := asn1.Unmarshal(derBytes, certList); err != nil {
  2280  		return nil, err
  2281  	} else if len(rest) != 0 {
  2282  		return nil, errors.New("x509: trailing data after CRL")
  2283  	}
  2284  	return certList, nil
  2285  }
  2286  
  2287  // CreateCRL returns a DER encoded CRL, signed by this Certificate, that
  2288  // contains the given list of revoked certificates.
  2289  //
  2290  // Note: this method does not generate an RFC 5280 conformant X.509 v2 CRL.
  2291  // To generate a standards compliant CRL, use CreateRevocationList instead.
  2292  func (c *Certificate) CreateCRL(rand io.Reader, priv interface{}, revokedCerts []pkix.RevokedCertificate, now, expiry time.Time) (crlBytes []byte, err error) {
  2293  	key, ok := priv.(crypto.Signer)
  2294  	if !ok {
  2295  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  2296  	}
  2297  
  2298  	hashFunc, signatureAlgorithm, err := signingParamsForPublicKey(key.Public(), 0)
  2299  	if err != nil {
  2300  		return nil, err
  2301  	}
  2302  
  2303  	// Force revocation times to UTC per RFC 5280.
  2304  	revokedCertsUTC := make([]pkix.RevokedCertificate, len(revokedCerts))
  2305  	for i, rc := range revokedCerts {
  2306  		rc.RevocationTime = rc.RevocationTime.UTC()
  2307  		revokedCertsUTC[i] = rc
  2308  	}
  2309  
  2310  	tbsCertList := pkix.TBSCertificateList{
  2311  		Version:             1,
  2312  		Signature:           signatureAlgorithm,
  2313  		Issuer:              c.Subject.ToRDNSequence(),
  2314  		ThisUpdate:          now.UTC(),
  2315  		NextUpdate:          expiry.UTC(),
  2316  		RevokedCertificates: revokedCertsUTC,
  2317  	}
  2318  
  2319  	// Authority Key Id
  2320  	if len(c.SubjectKeyId) > 0 {
  2321  		var aki pkix.Extension
  2322  		aki.Id = oidExtensionAuthorityKeyId
  2323  		aki.Value, err = asn1.Marshal(authKeyId{Id: c.SubjectKeyId})
  2324  		if err != nil {
  2325  			return
  2326  		}
  2327  		tbsCertList.Extensions = append(tbsCertList.Extensions, aki)
  2328  	}
  2329  
  2330  	tbsCertListContents, err := asn1.Marshal(tbsCertList)
  2331  	if err != nil {
  2332  		return
  2333  	}
  2334  
  2335  	signed := tbsCertListContents
  2336  	if hashFunc != 0 {
  2337  		h := hashFunc.New()
  2338  		h.Write(signed)
  2339  		signed = h.Sum(nil)
  2340  	}
  2341  
  2342  	var signature []byte
  2343  	signature, err = key.Sign(rand, signed, hashFunc)
  2344  	if err != nil {
  2345  		return
  2346  	}
  2347  
  2348  	return asn1.Marshal(pkix.CertificateList{
  2349  		TBSCertList:        tbsCertList,
  2350  		SignatureAlgorithm: signatureAlgorithm,
  2351  		SignatureValue:     asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  2352  	})
  2353  }
  2354  
  2355  // CertificateRequest represents a PKCS #10, certificate signature request.
  2356  type CertificateRequest struct {
  2357  	Raw                      []byte // Complete ASN.1 DER content (CSR, signature algorithm and signature).
  2358  	RawTBSCertificateRequest []byte // Certificate request info part of raw ASN.1 DER content.
  2359  	RawSubjectPublicKeyInfo  []byte // DER encoded SubjectPublicKeyInfo.
  2360  	RawSubject               []byte // DER encoded Subject.
  2361  
  2362  	Version            int
  2363  	Signature          []byte
  2364  	SignatureAlgorithm SignatureAlgorithm
  2365  
  2366  	PublicKeyAlgorithm PublicKeyAlgorithm
  2367  	PublicKey          interface{}
  2368  
  2369  	Subject pkix.Name
  2370  
  2371  	// Attributes contains the CSR attributes that can parse as
  2372  	// pkix.AttributeTypeAndValueSET.
  2373  	//
  2374  	// Deprecated: Use Extensions and ExtraExtensions instead for parsing and
  2375  	// generating the requestedExtensions attribute.
  2376  	Attributes []pkix.AttributeTypeAndValueSET
  2377  
  2378  	// Extensions contains all requested extensions, in raw form. When parsing
  2379  	// CSRs, this can be used to extract extensions that are not parsed by this
  2380  	// package.
  2381  	Extensions []pkix.Extension
  2382  
  2383  	// ExtraExtensions contains extensions to be copied, raw, into any CSR
  2384  	// marshaled by CreateCertificateRequest. Values override any extensions
  2385  	// that would otherwise be produced based on the other fields but are
  2386  	// overridden by any extensions specified in Attributes.
  2387  	//
  2388  	// The ExtraExtensions field is not populated by ParseCertificateRequest,
  2389  	// see Extensions instead.
  2390  	ExtraExtensions []pkix.Extension
  2391  
  2392  	// Subject Alternate Name values.
  2393  	DNSNames       []string
  2394  	EmailAddresses []string
  2395  	IPAddresses    []net.IP
  2396  	URIs           []*url.URL
  2397  }
  2398  
  2399  // These structures reflect the ASN.1 structure of X.509 certificate
  2400  // signature requests (see RFC 2986):
  2401  
  2402  type tbsCertificateRequest struct {
  2403  	Raw           asn1.RawContent
  2404  	Version       int
  2405  	Subject       asn1.RawValue
  2406  	PublicKey     publicKeyInfo
  2407  	RawAttributes []asn1.RawValue `asn1:"tag:0"`
  2408  }
  2409  
  2410  type certificateRequest struct {
  2411  	Raw                asn1.RawContent
  2412  	TBSCSR             tbsCertificateRequest
  2413  	SignatureAlgorithm pkix.AlgorithmIdentifier
  2414  	SignatureValue     asn1.BitString
  2415  }
  2416  
  2417  // oidExtensionRequest is a PKCS #9 OBJECT IDENTIFIER that indicates requested
  2418  // extensions in a CSR.
  2419  var oidExtensionRequest = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 9, 14}
  2420  
  2421  // newRawAttributes converts AttributeTypeAndValueSETs from a template
  2422  // CertificateRequest's Attributes into tbsCertificateRequest RawAttributes.
  2423  func newRawAttributes(attributes []pkix.AttributeTypeAndValueSET) ([]asn1.RawValue, error) {
  2424  	var rawAttributes []asn1.RawValue
  2425  	b, err := asn1.Marshal(attributes)
  2426  	if err != nil {
  2427  		return nil, err
  2428  	}
  2429  	rest, err := asn1.Unmarshal(b, &rawAttributes)
  2430  	if err != nil {
  2431  		return nil, err
  2432  	}
  2433  	if len(rest) != 0 {
  2434  		return nil, errors.New("x509: failed to unmarshal raw CSR Attributes")
  2435  	}
  2436  	return rawAttributes, nil
  2437  }
  2438  
  2439  // parseRawAttributes Unmarshals RawAttributes into AttributeTypeAndValueSETs.
  2440  func parseRawAttributes(rawAttributes []asn1.RawValue) []pkix.AttributeTypeAndValueSET {
  2441  	var attributes []pkix.AttributeTypeAndValueSET
  2442  	for _, rawAttr := range rawAttributes {
  2443  		var attr pkix.AttributeTypeAndValueSET
  2444  		rest, err := asn1.Unmarshal(rawAttr.FullBytes, &attr)
  2445  		// Ignore attributes that don't parse into pkix.AttributeTypeAndValueSET
  2446  		// (i.e.: challengePassword or unstructuredName).
  2447  		if err == nil && len(rest) == 0 {
  2448  			attributes = append(attributes, attr)
  2449  		}
  2450  	}
  2451  	return attributes
  2452  }
  2453  
  2454  // parseCSRExtensions parses the attributes from a CSR and extracts any
  2455  // requested extensions.
  2456  func parseCSRExtensions(rawAttributes []asn1.RawValue) ([]pkix.Extension, error) {
  2457  	// pkcs10Attribute reflects the Attribute structure from RFC 2986, Section 4.1.
  2458  	type pkcs10Attribute struct {
  2459  		Id     asn1.ObjectIdentifier
  2460  		Values []asn1.RawValue `asn1:"set"`
  2461  	}
  2462  
  2463  	var ret []pkix.Extension
  2464  	for _, rawAttr := range rawAttributes {
  2465  		var attr pkcs10Attribute
  2466  		if rest, err := asn1.Unmarshal(rawAttr.FullBytes, &attr); err != nil || len(rest) != 0 || len(attr.Values) == 0 {
  2467  			// Ignore attributes that don't parse.
  2468  			continue
  2469  		}
  2470  
  2471  		if !attr.Id.Equal(oidExtensionRequest) {
  2472  			continue
  2473  		}
  2474  
  2475  		var extensions []pkix.Extension
  2476  		if _, err := asn1.Unmarshal(attr.Values[0].FullBytes, &extensions); err != nil {
  2477  			return nil, err
  2478  		}
  2479  		ret = append(ret, extensions...)
  2480  	}
  2481  
  2482  	return ret, nil
  2483  }
  2484  
  2485  // CreateCertificateRequest creates a new certificate request based on a
  2486  // template. The following members of template are used:
  2487  //
  2488  //  - SignatureAlgorithm
  2489  //  - Subject
  2490  //  - DNSNames
  2491  //  - EmailAddresses
  2492  //  - IPAddresses
  2493  //  - URIs
  2494  //  - ExtraExtensions
  2495  //  - Attributes (deprecated)
  2496  //
  2497  // priv is the private key to sign the CSR with, and the corresponding public
  2498  // key will be included in the CSR. It must implement crypto.Signer and its
  2499  // Public() method must return a *rsa.PublicKey or a *ecdsa.PublicKey or a
  2500  // ed25519.PublicKey. (A *rsa.PrivateKey, *ecdsa.PrivateKey or
  2501  // ed25519.PrivateKey satisfies this.)
  2502  //
  2503  // The returned slice is the certificate request in DER encoding.
  2504  func CreateCertificateRequest(rand io.Reader, template *CertificateRequest, priv interface{}) (csr []byte, err error) {
  2505  	key, ok := priv.(crypto.Signer)
  2506  	if !ok {
  2507  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  2508  	}
  2509  
  2510  	var hashFunc crypto.Hash
  2511  	var sigAlgo pkix.AlgorithmIdentifier
  2512  	hashFunc, sigAlgo, err = signingParamsForPublicKey(key.Public(), template.SignatureAlgorithm)
  2513  	if err != nil {
  2514  		return nil, err
  2515  	}
  2516  
  2517  	var publicKeyBytes []byte
  2518  	var publicKeyAlgorithm pkix.AlgorithmIdentifier
  2519  	publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(key.Public())
  2520  	if err != nil {
  2521  		return nil, err
  2522  	}
  2523  
  2524  	extensions, err := buildCSRExtensions(template)
  2525  	if err != nil {
  2526  		return nil, err
  2527  	}
  2528  
  2529  	// Make a copy of template.Attributes because we may alter it below.
  2530  	attributes := make([]pkix.AttributeTypeAndValueSET, 0, len(template.Attributes))
  2531  	for _, attr := range template.Attributes {
  2532  		values := make([][]pkix.AttributeTypeAndValue, len(attr.Value))
  2533  		copy(values, attr.Value)
  2534  		attributes = append(attributes, pkix.AttributeTypeAndValueSET{
  2535  			Type:  attr.Type,
  2536  			Value: values,
  2537  		})
  2538  	}
  2539  
  2540  	extensionsAppended := false
  2541  	if len(extensions) > 0 {
  2542  		// Append the extensions to an existing attribute if possible.
  2543  		for _, atvSet := range attributes {
  2544  			if !atvSet.Type.Equal(oidExtensionRequest) || len(atvSet.Value) == 0 {
  2545  				continue
  2546  			}
  2547  
  2548  			// specifiedExtensions contains all the extensions that we
  2549  			// found specified via template.Attributes.
  2550  			specifiedExtensions := make(map[string]bool)
  2551  
  2552  			for _, atvs := range atvSet.Value {
  2553  				for _, atv := range atvs {
  2554  					specifiedExtensions[atv.Type.String()] = true
  2555  				}
  2556  			}
  2557  
  2558  			newValue := make([]pkix.AttributeTypeAndValue, 0, len(atvSet.Value[0])+len(extensions))
  2559  			newValue = append(newValue, atvSet.Value[0]...)
  2560  
  2561  			for _, e := range extensions {
  2562  				if specifiedExtensions[e.Id.String()] {
  2563  					// Attributes already contained a value for
  2564  					// this extension and it takes priority.
  2565  					continue
  2566  				}
  2567  
  2568  				newValue = append(newValue, pkix.AttributeTypeAndValue{
  2569  					// There is no place for the critical
  2570  					// flag in an AttributeTypeAndValue.
  2571  					Type:  e.Id,
  2572  					Value: e.Value,
  2573  				})
  2574  			}
  2575  
  2576  			atvSet.Value[0] = newValue
  2577  			extensionsAppended = true
  2578  			break
  2579  		}
  2580  	}
  2581  
  2582  	rawAttributes, err := newRawAttributes(attributes)
  2583  	if err != nil {
  2584  		return
  2585  	}
  2586  
  2587  	// If not included in attributes, add a new attribute for the
  2588  	// extensions.
  2589  	if len(extensions) > 0 && !extensionsAppended {
  2590  		attr := struct {
  2591  			Type  asn1.ObjectIdentifier
  2592  			Value [][]pkix.Extension `asn1:"set"`
  2593  		}{
  2594  			Type:  oidExtensionRequest,
  2595  			Value: [][]pkix.Extension{extensions},
  2596  		}
  2597  
  2598  		b, err := asn1.Marshal(attr)
  2599  		if err != nil {
  2600  			return nil, errors.New("x509: failed to serialise extensions attribute: " + err.Error())
  2601  		}
  2602  
  2603  		var rawValue asn1.RawValue
  2604  		if _, err := asn1.Unmarshal(b, &rawValue); err != nil {
  2605  			return nil, err
  2606  		}
  2607  
  2608  		rawAttributes = append(rawAttributes, rawValue)
  2609  	}
  2610  
  2611  	asn1Subject := template.RawSubject
  2612  	if len(asn1Subject) == 0 {
  2613  		asn1Subject, err = asn1.Marshal(template.Subject.ToRDNSequence())
  2614  		if err != nil {
  2615  			return nil, err
  2616  		}
  2617  	}
  2618  
  2619  	tbsCSR := tbsCertificateRequest{
  2620  		Version: 0, // PKCS #10, RFC 2986
  2621  		Subject: asn1.RawValue{FullBytes: asn1Subject},
  2622  		PublicKey: publicKeyInfo{
  2623  			Algorithm: publicKeyAlgorithm,
  2624  			PublicKey: asn1.BitString{
  2625  				Bytes:     publicKeyBytes,
  2626  				BitLength: len(publicKeyBytes) * 8,
  2627  			},
  2628  		},
  2629  		RawAttributes: rawAttributes,
  2630  	}
  2631  
  2632  	tbsCSRContents, err := asn1.Marshal(tbsCSR)
  2633  	if err != nil {
  2634  		return
  2635  	}
  2636  	tbsCSR.Raw = tbsCSRContents
  2637  
  2638  	signed := tbsCSRContents
  2639  	if hashFunc != 0 {
  2640  		h := hashFunc.New()
  2641  		h.Write(signed)
  2642  		signed = h.Sum(nil)
  2643  	}
  2644  
  2645  	var signature []byte
  2646  	signature, err = key.Sign(rand, signed, hashFunc)
  2647  	if err != nil {
  2648  		return
  2649  	}
  2650  
  2651  	return asn1.Marshal(certificateRequest{
  2652  		TBSCSR:             tbsCSR,
  2653  		SignatureAlgorithm: sigAlgo,
  2654  		SignatureValue: asn1.BitString{
  2655  			Bytes:     signature,
  2656  			BitLength: len(signature) * 8,
  2657  		},
  2658  	})
  2659  }
  2660  
  2661  // ParseCertificateRequest parses a single certificate request from the
  2662  // given ASN.1 DER data.
  2663  func ParseCertificateRequest(asn1Data []byte) (*CertificateRequest, error) {
  2664  	var csr certificateRequest
  2665  
  2666  	rest, err := asn1.Unmarshal(asn1Data, &csr)
  2667  	if err != nil {
  2668  		return nil, err
  2669  	} else if len(rest) != 0 {
  2670  		return nil, asn1.SyntaxError{Msg: "trailing data"}
  2671  	}
  2672  
  2673  	return parseCertificateRequest(&csr)
  2674  }
  2675  
  2676  func parseCertificateRequest(in *certificateRequest) (*CertificateRequest, error) {
  2677  	out := &CertificateRequest{
  2678  		Raw:                      in.Raw,
  2679  		RawTBSCertificateRequest: in.TBSCSR.Raw,
  2680  		RawSubjectPublicKeyInfo:  in.TBSCSR.PublicKey.Raw,
  2681  		RawSubject:               in.TBSCSR.Subject.FullBytes,
  2682  
  2683  		Signature:          in.SignatureValue.RightAlign(),
  2684  		SignatureAlgorithm: getSignatureAlgorithmFromAI(in.SignatureAlgorithm),
  2685  
  2686  		PublicKeyAlgorithm: getPublicKeyAlgorithmFromOID(in.TBSCSR.PublicKey.Algorithm.Algorithm),
  2687  
  2688  		Version:    in.TBSCSR.Version,
  2689  		Attributes: parseRawAttributes(in.TBSCSR.RawAttributes),
  2690  	}
  2691  
  2692  	var err error
  2693  	out.PublicKey, err = parsePublicKey(out.PublicKeyAlgorithm, &in.TBSCSR.PublicKey)
  2694  	if err != nil {
  2695  		return nil, err
  2696  	}
  2697  
  2698  	var subject pkix.RDNSequence
  2699  	if rest, err := asn1.Unmarshal(in.TBSCSR.Subject.FullBytes, &subject); err != nil {
  2700  		return nil, err
  2701  	} else if len(rest) != 0 {
  2702  		return nil, errors.New("x509: trailing data after X.509 Subject")
  2703  	}
  2704  
  2705  	out.Subject.FillFromRDNSequence(&subject)
  2706  
  2707  	if out.Extensions, err = parseCSRExtensions(in.TBSCSR.RawAttributes); err != nil {
  2708  		return nil, err
  2709  	}
  2710  
  2711  	for _, extension := range out.Extensions {
  2712  		switch {
  2713  		case extension.Id.Equal(oidExtensionSubjectAltName):
  2714  			out.DNSNames, out.EmailAddresses, out.IPAddresses, out.URIs, err = parseSANExtension(extension.Value)
  2715  			if err != nil {
  2716  				return nil, err
  2717  			}
  2718  		}
  2719  	}
  2720  
  2721  	return out, nil
  2722  }
  2723  
  2724  // CheckSignature reports whether the signature on c is valid.
  2725  func (c *CertificateRequest) CheckSignature() error {
  2726  	return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificateRequest, c.Signature, c.PublicKey)
  2727  }
  2728  
  2729  // RevocationList contains the fields used to create an X.509 v2 Certificate
  2730  // Revocation list with CreateRevocationList.
  2731  type RevocationList struct {
  2732  	// SignatureAlgorithm is used to determine the signature algorithm to be
  2733  	// used when signing the CRL. If 0 the default algorithm for the signing
  2734  	// key will be used.
  2735  	SignatureAlgorithm SignatureAlgorithm
  2736  
  2737  	// RevokedCertificates is used to populate the revokedCertificates
  2738  	// sequence in the CRL, it may be empty. RevokedCertificates may be nil,
  2739  	// in which case an empty CRL will be created.
  2740  	RevokedCertificates []pkix.RevokedCertificate
  2741  
  2742  	// Number is used to populate the X.509 v2 cRLNumber extension in the CRL,
  2743  	// which should be a monotonically increasing sequence number for a given
  2744  	// CRL scope and CRL issuer.
  2745  	Number *big.Int
  2746  	// ThisUpdate is used to populate the thisUpdate field in the CRL, which
  2747  	// indicates the issuance date of the CRL.
  2748  	ThisUpdate time.Time
  2749  	// NextUpdate is used to populate the nextUpdate field in the CRL, which
  2750  	// indicates the date by which the next CRL will be issued. NextUpdate
  2751  	// must be greater than ThisUpdate.
  2752  	NextUpdate time.Time
  2753  	// ExtraExtensions contains any additional extensions to add directly to
  2754  	// the CRL.
  2755  	ExtraExtensions []pkix.Extension
  2756  }
  2757  
  2758  // CreateRevocationList creates a new X.509 v2 Certificate Revocation List,
  2759  // according to RFC 5280, based on template.
  2760  //
  2761  // The CRL is signed by priv which should be the private key associated with
  2762  // the public key in the issuer certificate.
  2763  //
  2764  // The issuer may not be nil, and the crlSign bit must be set in KeyUsage in
  2765  // order to use it as a CRL issuer.
  2766  //
  2767  // The issuer distinguished name CRL field and authority key identifier
  2768  // extension are populated using the issuer certificate. issuer must have
  2769  // SubjectKeyId set.
  2770  func CreateRevocationList(rand io.Reader, template *RevocationList, issuer *Certificate, priv crypto.Signer) ([]byte, error) {
  2771  	if template == nil {
  2772  		return nil, errors.New("x509: template can not be nil")
  2773  	}
  2774  	if issuer == nil {
  2775  		return nil, errors.New("x509: issuer can not be nil")
  2776  	}
  2777  	if (issuer.KeyUsage & KeyUsageCRLSign) == 0 {
  2778  		return nil, errors.New("x509: issuer must have the crlSign key usage bit set")
  2779  	}
  2780  	if len(issuer.SubjectKeyId) == 0 {
  2781  		return nil, errors.New("x509: issuer certificate doesn't contain a subject key identifier")
  2782  	}
  2783  	if template.NextUpdate.Before(template.ThisUpdate) {
  2784  		return nil, errors.New("x509: template.ThisUpdate is after template.NextUpdate")
  2785  	}
  2786  	if template.Number == nil {
  2787  		return nil, errors.New("x509: template contains nil Number field")
  2788  	}
  2789  
  2790  	hashFunc, signatureAlgorithm, err := signingParamsForPublicKey(priv.Public(), template.SignatureAlgorithm)
  2791  	if err != nil {
  2792  		return nil, err
  2793  	}
  2794  
  2795  	// Force revocation times to UTC per RFC 5280.
  2796  	revokedCertsUTC := make([]pkix.RevokedCertificate, len(template.RevokedCertificates))
  2797  	for i, rc := range template.RevokedCertificates {
  2798  		rc.RevocationTime = rc.RevocationTime.UTC()
  2799  		revokedCertsUTC[i] = rc
  2800  	}
  2801  
  2802  	aki, err := asn1.Marshal(authKeyId{Id: issuer.SubjectKeyId})
  2803  	if err != nil {
  2804  		return nil, err
  2805  	}
  2806  	crlNum, err := asn1.Marshal(template.Number)
  2807  	if err != nil {
  2808  		return nil, err
  2809  	}
  2810  
  2811  	tbsCertList := pkix.TBSCertificateList{
  2812  		Version:    1, // v2
  2813  		Signature:  signatureAlgorithm,
  2814  		Issuer:     issuer.Subject.ToRDNSequence(),
  2815  		ThisUpdate: template.ThisUpdate.UTC(),
  2816  		NextUpdate: template.NextUpdate.UTC(),
  2817  		Extensions: []pkix.Extension{
  2818  			{
  2819  				Id:    oidExtensionAuthorityKeyId,
  2820  				Value: aki,
  2821  			},
  2822  			{
  2823  				Id:    oidExtensionCRLNumber,
  2824  				Value: crlNum,
  2825  			},
  2826  		},
  2827  	}
  2828  	if len(revokedCertsUTC) > 0 {
  2829  		tbsCertList.RevokedCertificates = revokedCertsUTC
  2830  	}
  2831  
  2832  	if len(template.ExtraExtensions) > 0 {
  2833  		tbsCertList.Extensions = append(tbsCertList.Extensions, template.ExtraExtensions...)
  2834  	}
  2835  
  2836  	tbsCertListContents, err := asn1.Marshal(tbsCertList)
  2837  	if err != nil {
  2838  		return nil, err
  2839  	}
  2840  
  2841  	input := tbsCertListContents
  2842  	if hashFunc != 0 {
  2843  		h := hashFunc.New()
  2844  		h.Write(tbsCertListContents)
  2845  		input = h.Sum(nil)
  2846  	}
  2847  	var signerOpts crypto.SignerOpts = hashFunc
  2848  	if template.SignatureAlgorithm.isRSAPSS() {
  2849  		signerOpts = &rsa.PSSOptions{
  2850  			SaltLength: rsa.PSSSaltLengthEqualsHash,
  2851  			Hash:       hashFunc,
  2852  		}
  2853  	}
  2854  
  2855  	signature, err := priv.Sign(rand, input, signerOpts)
  2856  	if err != nil {
  2857  		return nil, err
  2858  	}
  2859  
  2860  	return asn1.Marshal(pkix.CertificateList{
  2861  		TBSCertList:        tbsCertList,
  2862  		SignatureAlgorithm: signatureAlgorithm,
  2863  		SignatureValue:     asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  2864  	})
  2865  }
  2866  

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