libgo/go/crypto/sha1/sha1block.go

   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 // +build !amd64,!386
   6
   7 // SHA1 block step.
   8 // In its own file so that a faster assembly or C version
   9 // can be substituted easily.
  10
  11 package sha1
  12
  13 const (
  14         _K0 = 0x5A827999
  15         _K1 = 0x6ED9EBA1
  16         _K2 = 0x8F1BBCDC
  17         _K3 = 0xCA62C1D6
  18 )
  19
  20 func block(dig *digest, p []byte) {
  21         var w [16]uint32
  22
  23         h0, h1, h2, h3, h4 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4]
  24         for len(p) >= chunk {
  25                 // Can interlace the computation of w with the
  26                 // rounds below if needed for speed.
  27                 for i := 0; i < 16; i++ {
  28                         j := i * 4
  29                         w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3])
  30                 }
  31
  32                 a, b, c, d, e := h0, h1, h2, h3, h4
  33
  34                 // Each of the four 20-iteration rounds
  35                 // differs only in the computation of f and
  36                 // the choice of K (_K0, _K1, etc).
  37                 i := 0
  38                 for ; i < 16; i++ {
  39                         f := b&c | (^b)&d
  40                         a5 := a<<5 | a>>(32-5)
  41                         b30 := b<<30 | b>>(32-30)
  42                         t := a5 + f + e + w[i&0xf] + _K0
  43                         a, b, c, d, e = t, a, b30, c, d
  44                 }
  45                 for ; i < 20; i++ {
  46                         tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
  47                         w[i&0xf] = tmp<<1 | tmp>>(32-1)
  48
  49                         f := b&c | (^b)&d
  50                         a5 := a<<5 | a>>(32-5)
  51                         b30 := b<<30 | b>>(32-30)
  52                         t := a5 + f + e + w[i&0xf] + _K0
  53                         a, b, c, d, e = t, a, b30, c, d
  54                 }
  55                 for ; i < 40; i++ {
  56                         tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
  57                         w[i&0xf] = tmp<<1 | tmp>>(32-1)
  58                         f := b ^ c ^ d
  59                         a5 := a<<5 | a>>(32-5)
  60                         b30 := b<<30 | b>>(32-30)
  61                         t := a5 + f + e + w[i&0xf] + _K1
  62                         a, b, c, d, e = t, a, b30, c, d
  63                 }
  64                 for ; i < 60; i++ {
  65                         tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
  66                         w[i&0xf] = tmp<<1 | tmp>>(32-1)
  67                         f := ((b | c) & d) | (b & c)
  68
  69                         a5 := a<<5 | a>>(32-5)
  70                         b30 := b<<30 | b>>(32-30)
  71                         t := a5 + f + e + w[i&0xf] + _K2
  72                         a, b, c, d, e = t, a, b30, c, d
  73                 }
  74                 for ; i < 80; i++ {
  75                         tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
  76                         w[i&0xf] = tmp<<1 | tmp>>(32-1)
  77                         f := b ^ c ^ d
  78                         a5 := a<<5 | a>>(32-5)
  79                         b30 := b<<30 | b>>(32-30)
  80                         t := a5 + f + e + w[i&0xf] + _K3
  81                         a, b, c, d, e = t, a, b30, c, d
  82                 }
  83
  84                 h0 += a
  85                 h1 += b
  86                 h2 += c
  87                 h3 += d
  88                 h4 += e
  89
  90                 p = p[chunk:]
  91         }
  92
  93         dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4] = h0, h1, h2, h3, h4
  94 }