| // 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] = bits.RotateLeft32(tmp, 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] = bits.RotateLeft32(tmp, 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] = bits.RotateLeft32(tmp, 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] = bits.RotateLeft32(tmp, 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 |
| } |