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Source file src/crypto/crypto.go

Documentation: crypto

  // Copyright 2011 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // Package crypto collects common cryptographic constants.
  package crypto
  
  import (
  	"hash"
  	"io"
  	"strconv"
  )
  
  // Hash identifies a cryptographic hash function that is implemented in another
  // package.
  type Hash uint
  
  // HashFunc simply returns the value of h so that Hash implements SignerOpts.
  func (h Hash) HashFunc() Hash {
  	return h
  }
  
  const (
  	MD4         Hash = 1 + iota // import golang.org/x/crypto/md4
  	MD5                         // import crypto/md5
  	SHA1                        // import crypto/sha1
  	SHA224                      // import crypto/sha256
  	SHA256                      // import crypto/sha256
  	SHA384                      // import crypto/sha512
  	SHA512                      // import crypto/sha512
  	MD5SHA1                     // no implementation; MD5+SHA1 used for TLS RSA
  	RIPEMD160                   // import golang.org/x/crypto/ripemd160
  	SHA3_224                    // import golang.org/x/crypto/sha3
  	SHA3_256                    // import golang.org/x/crypto/sha3
  	SHA3_384                    // import golang.org/x/crypto/sha3
  	SHA3_512                    // import golang.org/x/crypto/sha3
  	SHA512_224                  // import crypto/sha512
  	SHA512_256                  // import crypto/sha512
  	BLAKE2s_256                 // import golang.org/x/crypto/blake2s
  	BLAKE2b_256                 // import golang.org/x/crypto/blake2b
  	BLAKE2b_384                 // import golang.org/x/crypto/blake2b
  	BLAKE2b_512                 // import golang.org/x/crypto/blake2b
  	maxHash
  )
  
  var digestSizes = []uint8{
  	MD4:         16,
  	MD5:         16,
  	SHA1:        20,
  	SHA224:      28,
  	SHA256:      32,
  	SHA384:      48,
  	SHA512:      64,
  	SHA512_224:  28,
  	SHA512_256:  32,
  	SHA3_224:    28,
  	SHA3_256:    32,
  	SHA3_384:    48,
  	SHA3_512:    64,
  	MD5SHA1:     36,
  	RIPEMD160:   20,
  	BLAKE2s_256: 32,
  	BLAKE2b_256: 32,
  	BLAKE2b_384: 48,
  	BLAKE2b_512: 64,
  }
  
  // Size returns the length, in bytes, of a digest resulting from the given hash
  // function. It doesn't require that the hash function in question be linked
  // into the program.
  func (h Hash) Size() int {
  	if h > 0 && h < maxHash {
  		return int(digestSizes[h])
  	}
  	panic("crypto: Size of unknown hash function")
  }
  
  var hashes = make([]func() hash.Hash, maxHash)
  
  // New returns a new hash.Hash calculating the given hash function. New panics
  // if the hash function is not linked into the binary.
  func (h Hash) New() hash.Hash {
  	if h > 0 && h < maxHash {
  		f := hashes[h]
  		if f != nil {
  			return f()
  		}
  	}
  	panic("crypto: requested hash function #" + strconv.Itoa(int(h)) + " is unavailable")
  }
  
  // Available reports whether the given hash function is linked into the binary.
  func (h Hash) Available() bool {
  	return h < maxHash && hashes[h] != nil
  }
  
  // RegisterHash registers a function that returns a new instance of the given
  // hash function. This is intended to be called from the init function in
  // packages that implement hash functions.
  func RegisterHash(h Hash, f func() hash.Hash) {
  	if h >= maxHash {
  		panic("crypto: RegisterHash of unknown hash function")
  	}
  	hashes[h] = f
  }
  
  // PublicKey represents a public key using an unspecified algorithm.
  type PublicKey interface{}
  
  // PrivateKey represents a private key using an unspecified algorithm.
  type PrivateKey interface{}
  
  // Signer is an interface for an opaque private key that can be used for
  // signing operations. For example, an RSA key kept in a hardware module.
  type Signer interface {
  	// Public returns the public key corresponding to the opaque,
  	// private key.
  	Public() PublicKey
  
  	// Sign signs digest with the private key, possibly using entropy from
  	// rand. For an RSA key, the resulting signature should be either a
  	// PKCS#1 v1.5 or PSS signature (as indicated by opts). For an (EC)DSA
  	// key, it should be a DER-serialised, ASN.1 signature structure.
  	//
  	// Hash implements the SignerOpts interface and, in most cases, one can
  	// simply pass in the hash function used as opts. Sign may also attempt
  	// to type assert opts to other types in order to obtain algorithm
  	// specific values. See the documentation in each package for details.
  	//
  	// Note that when a signature of a hash of a larger message is needed,
  	// the caller is responsible for hashing the larger message and passing
  	// the hash (as digest) and the hash function (as opts) to Sign.
  	Sign(rand io.Reader, digest []byte, opts SignerOpts) (signature []byte, err error)
  }
  
  // SignerOpts contains options for signing with a Signer.
  type SignerOpts interface {
  	// HashFunc returns an identifier for the hash function used to produce
  	// the message passed to Signer.Sign, or else zero to indicate that no
  	// hashing was done.
  	HashFunc() Hash
  }
  
  // Decrypter is an interface for an opaque private key that can be used for
  // asymmetric decryption operations. An example would be an RSA key
  // kept in a hardware module.
  type Decrypter interface {
  	// Public returns the public key corresponding to the opaque,
  	// private key.
  	Public() PublicKey
  
  	// Decrypt decrypts msg. The opts argument should be appropriate for
  	// the primitive used. See the documentation in each implementation for
  	// details.
  	Decrypt(rand io.Reader, msg []byte, opts DecrypterOpts) (plaintext []byte, err error)
  }
  
  type DecrypterOpts interface{}
  

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