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Source file src/crypto/aes/cipher_s390x.go

Documentation: crypto/aes

     1  // Copyright 2016 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 aes
     6  
     7  import (
     8  	"crypto/cipher"
     9  	"crypto/internal/subtle"
    10  	"internal/cpu"
    11  )
    12  
    13  type code int
    14  
    15  // Function codes for the cipher message family of instructions.
    16  const (
    17  	aes128 code = 18
    18  	aes192      = 19
    19  	aes256      = 20
    20  )
    21  
    22  type aesCipherAsm struct {
    23  	function code     // code for cipher message instruction
    24  	key      []byte   // key (128, 192 or 256 bits)
    25  	storage  [32]byte // array backing key slice
    26  }
    27  
    28  // cryptBlocks invokes the cipher message (KM) instruction with
    29  // the given function code. This is equivalent to AES in ECB
    30  // mode. The length must be a multiple of BlockSize (16).
    31  //go:noescape
    32  func cryptBlocks(c code, key, dst, src *byte, length int)
    33  
    34  func newCipher(key []byte) (cipher.Block, error) {
    35  	// The aesCipherAsm type implements the cbcEncAble, cbcDecAble,
    36  	// ctrAble and gcmAble interfaces. We therefore need to check
    37  	// for all the features required to implement these modes.
    38  	// Keep in sync with crypto/tls/common.go.
    39  	if !(cpu.S390X.HasAES && cpu.S390X.HasAESCBC && cpu.S390X.HasAESCTR && (cpu.S390X.HasGHASH || cpu.S390X.HasAESGCM)) {
    40  		return newCipherGeneric(key)
    41  	}
    42  
    43  	var function code
    44  	switch len(key) {
    45  	case 128 / 8:
    46  		function = aes128
    47  	case 192 / 8:
    48  		function = aes192
    49  	case 256 / 8:
    50  		function = aes256
    51  	default:
    52  		return nil, KeySizeError(len(key))
    53  	}
    54  
    55  	var c aesCipherAsm
    56  	c.function = function
    57  	c.key = c.storage[:len(key)]
    58  	copy(c.key, key)
    59  	return &c, nil
    60  }
    61  
    62  func (c *aesCipherAsm) BlockSize() int { return BlockSize }
    63  
    64  func (c *aesCipherAsm) Encrypt(dst, src []byte) {
    65  	if len(src) < BlockSize {
    66  		panic("crypto/aes: input not full block")
    67  	}
    68  	if len(dst) < BlockSize {
    69  		panic("crypto/aes: output not full block")
    70  	}
    71  	if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
    72  		panic("crypto/aes: invalid buffer overlap")
    73  	}
    74  	cryptBlocks(c.function, &c.key[0], &dst[0], &src[0], BlockSize)
    75  }
    76  
    77  func (c *aesCipherAsm) Decrypt(dst, src []byte) {
    78  	if len(src) < BlockSize {
    79  		panic("crypto/aes: input not full block")
    80  	}
    81  	if len(dst) < BlockSize {
    82  		panic("crypto/aes: output not full block")
    83  	}
    84  	if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
    85  		panic("crypto/aes: invalid buffer overlap")
    86  	}
    87  	// The decrypt function code is equal to the function code + 128.
    88  	cryptBlocks(c.function+128, &c.key[0], &dst[0], &src[0], BlockSize)
    89  }
    90  
    91  // expandKey is used by BenchmarkExpand. cipher message (KM) does not need key
    92  // expansion so there is no assembly equivalent.
    93  func expandKey(key []byte, enc, dec []uint32) {
    94  	expandKeyGo(key, enc, dec)
    95  }
    96  

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