84 lines
2.3 KiB
Go
84 lines
2.3 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package sha1
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import (
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"math/bits"
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)
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const (
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_K0 = 0x5A827999
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_K1 = 0x6ED9EBA1
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_K2 = 0x8F1BBCDC
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_K3 = 0xCA62C1D6
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)
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// blockGeneric is a portable, pure Go version of the SHA-1 block step.
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// It's used by sha1block_generic.go and tests.
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func blockGeneric(dig *digest, p []byte) {
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var w [16]uint32
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h0, h1, h2, h3, h4 := dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4]
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for len(p) >= chunk {
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// Can interlace the computation of w with the
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// rounds below if needed for speed.
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for i := 0; i < 16; i++ {
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j := i * 4
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w[i] = uint32(p[j])<<24 | uint32(p[j+1])<<16 | uint32(p[j+2])<<8 | uint32(p[j+3])
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}
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a, b, c, d, e := h0, h1, h2, h3, h4
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// Each of the four 20-iteration rounds
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// differs only in the computation of f and
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// the choice of K (_K0, _K1, etc).
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i := 0
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for ; i < 16; i++ {
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f := b&c | (^b)&d
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t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K0
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a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d
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}
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for ; i < 20; i++ {
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tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
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w[i&0xf] = tmp<<1 | tmp>>(32-1)
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f := b&c | (^b)&d
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t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K0
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a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d
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}
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for ; i < 40; i++ {
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tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
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w[i&0xf] = tmp<<1 | tmp>>(32-1)
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f := b ^ c ^ d
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t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K1
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a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d
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}
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for ; i < 60; i++ {
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tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
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w[i&0xf] = tmp<<1 | tmp>>(32-1)
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f := ((b | c) & d) | (b & c)
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t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K2
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a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d
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}
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for ; i < 80; i++ {
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tmp := w[(i-3)&0xf] ^ w[(i-8)&0xf] ^ w[(i-14)&0xf] ^ w[(i)&0xf]
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w[i&0xf] = tmp<<1 | tmp>>(32-1)
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f := b ^ c ^ d
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t := bits.RotateLeft32(a, 5) + f + e + w[i&0xf] + _K3
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a, b, c, d, e = t, a, bits.RotateLeft32(b, 30), c, d
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}
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h0 += a
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h1 += b
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h2 += c
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h3 += d
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h4 += e
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p = p[chunk:]
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}
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dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4] = h0, h1, h2, h3, h4
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}
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