github.com/mattn/go@v0.0.0-20171011075504-07f7db3ea99f/src/crypto/aes/cipher_s390x.go (about)

     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/cipherhw"
    10  )
    11  
    12  type code int
    13  
    14  // Function codes for the cipher message family of instructions.
    15  const (
    16  	aes128 code = 18
    17  	aes192      = 19
    18  	aes256      = 20
    19  )
    20  
    21  type aesCipherAsm struct {
    22  	function code      // code for cipher message instruction
    23  	key      []byte    // key (128, 192 or 256 bytes)
    24  	storage  [256]byte // array backing key slice
    25  }
    26  
    27  // cryptBlocks invokes the cipher message (KM) instruction with
    28  // the given function code. This is equivalent to AES in ECB
    29  // mode. The length must be a multiple of BlockSize (16).
    30  //go:noescape
    31  func cryptBlocks(c code, key, dst, src *byte, length int)
    32  
    33  var useAsm = cipherhw.AESGCMSupport()
    34  
    35  func newCipher(key []byte) (cipher.Block, error) {
    36  	if !useAsm {
    37  		return newCipherGeneric(key)
    38  	}
    39  
    40  	var function code
    41  	switch len(key) {
    42  	case 128 / 8:
    43  		function = aes128
    44  	case 192 / 8:
    45  		function = aes192
    46  	case 256 / 8:
    47  		function = aes256
    48  	default:
    49  		return nil, KeySizeError(len(key))
    50  	}
    51  
    52  	var c aesCipherAsm
    53  	c.function = function
    54  	c.key = c.storage[:len(key)]
    55  	copy(c.key, key)
    56  	return &c, nil
    57  }
    58  
    59  func (c *aesCipherAsm) BlockSize() int { return BlockSize }
    60  
    61  func (c *aesCipherAsm) Encrypt(dst, src []byte) {
    62  	if len(src) < BlockSize {
    63  		panic("crypto/aes: input not full block")
    64  	}
    65  	if len(dst) < BlockSize {
    66  		panic("crypto/aes: output not full block")
    67  	}
    68  	cryptBlocks(c.function, &c.key[0], &dst[0], &src[0], BlockSize)
    69  }
    70  
    71  func (c *aesCipherAsm) Decrypt(dst, src []byte) {
    72  	if len(src) < BlockSize {
    73  		panic("crypto/aes: input not full block")
    74  	}
    75  	if len(dst) < BlockSize {
    76  		panic("crypto/aes: output not full block")
    77  	}
    78  	// The decrypt function code is equal to the function code + 128.
    79  	cryptBlocks(c.function+128, &c.key[0], &dst[0], &src[0], BlockSize)
    80  }
    81  
    82  // expandKey is used by BenchmarkExpand. cipher message (KM) does not need key
    83  // expansion so there is no assembly equivalent.
    84  func expandKey(key []byte, enc, dec []uint32) {
    85  	expandKeyGo(key, enc, dec)
    86  }