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 package sha1 6 7 const ( 8 _K0 = 0x5A827999 9 _K1 = 0x6ED9EBA1 10 _K2 = 0x8F1BBCDC 11 _K3 = 0xCA62C1D6 12 ) 13 14 // blockGeneric is a portable, pure Go version of the SHA1 block step. 15 // It's used by sha1block_generic.go and tests. 16 func blockGeneric(dig *digest, p []byte) { 17 var w [16]uint32 18 19 h0, h1, h2, h3, h4 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4] 20 for len(p) >= chunk { 21 // Can interlace the computation of w with the 22 // rounds below if needed for speed. 23 for i := 0; i < 16; i++ { 24 j := i * 4 25 w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3]) 26 } 27 28 a, b, c, d, e := h0, h1, h2, h3, h4 29 30 // Each of the four 20-iteration rounds 31 // differs only in the computation of f and 32 // the choice of K (_K0, _K1, etc). 33 i := 0 34 for ; i < 16; i++ { 35 f := b&c | (^b)&d 36 a5 := a<<5 | a>>(32-5) 37 b30 := b<<30 | b>>(32-30) 38 t := a5 + f + e + w[i&0xf] + _K0 39 a, b, c, d, e = t, a, b30, c, d 40 } 41 for ; i < 20; i++ { 42 tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf] 43 w[i&0xf] = tmp<<1 | tmp>>(32-1) 44 45 f := b&c | (^b)&d 46 a5 := a<<5 | a>>(32-5) 47 b30 := b<<30 | b>>(32-30) 48 t := a5 + f + e + w[i&0xf] + _K0 49 a, b, c, d, e = t, a, b30, c, d 50 } 51 for ; i < 40; i++ { 52 tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf] 53 w[i&0xf] = tmp<<1 | tmp>>(32-1) 54 f := b ^ c ^ d 55 a5 := a<<5 | a>>(32-5) 56 b30 := b<<30 | b>>(32-30) 57 t := a5 + f + e + w[i&0xf] + _K1 58 a, b, c, d, e = t, a, b30, c, d 59 } 60 for ; i < 60; i++ { 61 tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf] 62 w[i&0xf] = tmp<<1 | tmp>>(32-1) 63 f := ((b | c) & d) | (b & c) 64 65 a5 := a<<5 | a>>(32-5) 66 b30 := b<<30 | b>>(32-30) 67 t := a5 + f + e + w[i&0xf] + _K2 68 a, b, c, d, e = t, a, b30, c, d 69 } 70 for ; i < 80; i++ { 71 tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf] 72 w[i&0xf] = tmp<<1 | tmp>>(32-1) 73 f := b ^ c ^ d 74 a5 := a<<5 | a>>(32-5) 75 b30 := b<<30 | b>>(32-30) 76 t := a5 + f + e + w[i&0xf] + _K3 77 a, b, c, d, e = t, a, b30, c, d 78 } 79 80 h0 += a 81 h1 += b 82 h2 += c 83 h3 += d 84 h4 += e 85 86 p = p[chunk:] 87 } 88 89 dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4] = h0, h1, h2, h3, h4 90 } 91
