Source file src/crypto/aes/cipher_asm.go

Documentation: crypto/aes

     1  // Copyright 2012 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  // +build amd64 arm64
     6  
     7  package aes
     8  
     9  import (
    10  	"crypto/cipher"
    11  	"crypto/internal/subtle"
    12  	"internal/cpu"
    13  )
    14  
    15  // defined in asm_*.s
    16  
    17  //go:noescape
    18  func encryptBlockAsm(nr int, xk *uint32, dst, src *byte)
    19  
    20  //go:noescape
    21  func decryptBlockAsm(nr int, xk *uint32, dst, src *byte)
    22  
    23  //go:noescape
    24  func expandKeyAsm(nr int, key *byte, enc *uint32, dec *uint32)
    25  
    26  type aesCipherAsm struct {
    27  	aesCipher
    28  }
    29  
    30  var supportsAES = cpu.X86.HasAES || cpu.ARM64.HasAES
    31  var supportsGFMUL = cpu.X86.HasPCLMULQDQ || cpu.ARM64.HasPMULL
    32  
    33  func newCipher(key []byte) (cipher.Block, error) {
    34  	if !supportsAES {
    35  		return newCipherGeneric(key)
    36  	}
    37  	n := len(key) + 28
    38  	c := aesCipherAsm{aesCipher{make([]uint32, n), make([]uint32, n)}}
    39  	var rounds int
    40  	switch len(key) {
    41  	case 128 / 8:
    42  		rounds = 10
    43  	case 192 / 8:
    44  		rounds = 12
    45  	case 256 / 8:
    46  		rounds = 14
    47  	}
    48  
    49  	expandKeyAsm(rounds, &key[0], &c.enc[0], &c.dec[0])
    50  	if supportsAES && supportsGFMUL {
    51  		return &aesCipherGCM{c}, nil
    52  	}
    53  	return &c, nil
    54  }
    55  
    56  func (c *aesCipherAsm) BlockSize() int { return BlockSize }
    57  
    58  func (c *aesCipherAsm) Encrypt(dst, src []byte) {
    59  	if len(src) < BlockSize {
    60  		panic("crypto/aes: input not full block")
    61  	}
    62  	if len(dst) < BlockSize {
    63  		panic("crypto/aes: output not full block")
    64  	}
    65  	if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
    66  		panic("crypto/aes: invalid buffer overlap")
    67  	}
    68  	encryptBlockAsm(len(c.enc)/4-1, &c.enc[0], &dst[0], &src[0])
    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  	if subtle.InexactOverlap(dst[:BlockSize], src[:BlockSize]) {
    79  		panic("crypto/aes: invalid buffer overlap")
    80  	}
    81  	decryptBlockAsm(len(c.dec)/4-1, &c.dec[0], &dst[0], &src[0])
    82  }
    83  
    84  // expandKey is used by BenchmarkExpand to ensure that the asm implementation
    85  // of key expansion is used for the benchmark when it is available.
    86  func expandKey(key []byte, enc, dec []uint32) {
    87  	if supportsAES {
    88  		rounds := 10 // rounds needed for AES128
    89  		switch len(key) {
    90  		case 192 / 8:
    91  			rounds = 12
    92  		case 256 / 8:
    93  			rounds = 14
    94  		}
    95  		expandKeyAsm(rounds, &key[0], &enc[0], &dec[0])
    96  	} else {
    97  		expandKeyGo(key, enc, dec)
    98  	}
    99  }
   100  

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