blob: b5d32af70949c394ac527ffc57e51b9d44623b44 [file] [log] [blame]
 // Copyright 2009 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // SHA1 block step. // In its own file so that a faster assembly or C version // can be substituted easily. package sha1 const ( _K0 = 0x5A827999 _K1 = 0x6ED9EBA1 _K2 = 0x8F1BBCDC _K3 = 0xCA62C1D6 ) func _Block(dig *digest, p []byte) int { var w [80]uint32 n := 0 h0, h1, h2, h3, h4 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4] for len(p) >= _Chunk { // Can interlace the computation of w with the // rounds below if needed for speed. for i := 0; i < 16; i++ { j := i * 4 w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3]) } for i := 16; i < 80; i++ { tmp := w[i-3] ^ w[i-8] ^ w[i-14] ^ w[i-16] w[i] = tmp<<1 | tmp>>(32-1) } a, b, c, d, e := h0, h1, h2, h3, h4 // Each of the four 20-iteration rounds // differs only in the computation of f and // the choice of K (_K0, _K1, etc). for i := 0; i < 20; i++ { f := b&c | (^b)&d a5 := a<<5 | a>>(32-5) b30 := b<<30 | b>>(32-30) t := a5 + f + e + w[i] + _K0 a, b, c, d, e = t, a, b30, c, d } for i := 20; i < 40; i++ { f := b ^ c ^ d a5 := a<<5 | a>>(32-5) b30 := b<<30 | b>>(32-30) t := a5 + f + e + w[i] + _K1 a, b, c, d, e = t, a, b30, c, d } for i := 40; i < 60; i++ { f := b&c | b&d | c&d a5 := a<<5 | a>>(32-5) b30 := b<<30 | b>>(32-30) t := a5 + f + e + w[i] + _K2 a, b, c, d, e = t, a, b30, c, d } for i := 60; i < 80; i++ { f := b ^ c ^ d a5 := a<<5 | a>>(32-5) b30 := b<<30 | b>>(32-30) t := a5 + f + e + w[i] + _K3 a, b, c, d, e = t, a, b30, c, d } h0 += a h1 += b h2 += c h3 += d h4 += e p = p[_Chunk:] n += _Chunk } dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4] = h0, h1, h2, h3, h4 return n }