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