// 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. package sha1 import ( "math/bits" ) const ( _K0 = 0x5A827999 _K1 = 0x6ED9EBA1 _K2 = 0x8F1BBCDC _K3 = 0xCA62C1D6 ) // blockGeneric is a portable, pure Go version of the SHA-1 block step. // It's used by sha1block_generic.go and tests. func blockGeneric(dig *digest, p []byte) { var w [16]uint32 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]) } 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). i := 0 for ; i < 16; i++ { f := b&c | (^b)&d t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K0 a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d } for ; i < 20; i++ { tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf] w[i&0xf] = tmp<<1 | tmp>>(32-1) f := b&c | (^b)&d t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K0 a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d } for ; i < 40; i++ { tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf] w[i&0xf] = tmp<<1 | tmp>>(32-1) f := b ^ c ^ d t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K1 a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d } for ; i < 60; i++ { tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf] w[i&0xf] = tmp<<1 | tmp>>(32-1) f := ((b | c) & d) | (b & c) t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K2 a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d } for ; i < 80; i++ { tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf] w[i&0xf] = tmp<<1 | tmp>>(32-1) f := b ^ c ^ d t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K3 a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d } h0 += a h1 += b h2 += c h3 += d h4 += e p = p[chunk:] } dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4] = h0, h1, h2, h3, h4 }