117 lines
2.0 KiB
Go
117 lines
2.0 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 implements the SHA1 hash algorithm as defined in RFC 3174.
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package sha1
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import (
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"crypto"
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"hash"
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)
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func init() {
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crypto.RegisterHash(crypto.SHA1, New)
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}
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// The size of a SHA1 checksum in bytes.
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const Size = 20
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const (
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_Chunk = 64
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_Init0 = 0x67452301
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_Init1 = 0xEFCDAB89
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_Init2 = 0x98BADCFE
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_Init3 = 0x10325476
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_Init4 = 0xC3D2E1F0
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)
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// digest represents the partial evaluation of a checksum.
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type digest struct {
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h [5]uint32
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x [_Chunk]byte
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nx int
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len uint64
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}
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func (d *digest) Reset() {
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d.h[0] = _Init0
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d.h[1] = _Init1
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d.h[2] = _Init2
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d.h[3] = _Init3
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d.h[4] = _Init4
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d.nx = 0
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d.len = 0
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}
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// New returns a new hash.Hash computing the SHA1 checksum.
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func New() hash.Hash {
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d := new(digest)
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d.Reset()
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return d
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}
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func (d *digest) Size() int { return Size }
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func (d *digest) Write(p []byte) (nn int, err error) {
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nn = len(p)
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d.len += uint64(nn)
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if d.nx > 0 {
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n := len(p)
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if n > _Chunk-d.nx {
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n = _Chunk - d.nx
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}
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for i := 0; i < n; i++ {
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d.x[d.nx+i] = p[i]
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}
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d.nx += n
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if d.nx == _Chunk {
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_Block(d, d.x[0:])
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d.nx = 0
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}
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p = p[n:]
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}
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n := _Block(d, p)
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p = p[n:]
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if len(p) > 0 {
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d.nx = copy(d.x[:], p)
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}
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return
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}
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func (d0 *digest) Sum(in []byte) []byte {
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// Make a copy of d0 so that caller can keep writing and summing.
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d := *d0
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// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
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len := d.len
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var tmp [64]byte
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tmp[0] = 0x80
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if len%64 < 56 {
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d.Write(tmp[0 : 56-len%64])
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} else {
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d.Write(tmp[0 : 64+56-len%64])
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}
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// Length in bits.
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len <<= 3
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for i := uint(0); i < 8; i++ {
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tmp[i] = byte(len >> (56 - 8*i))
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}
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d.Write(tmp[0:8])
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if d.nx != 0 {
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panic("d.nx != 0")
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}
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var digest [Size]byte
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for i, s := range d.h {
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digest[i*4] = byte(s >> 24)
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digest[i*4+1] = byte(s >> 16)
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digest[i*4+2] = byte(s >> 8)
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digest[i*4+3] = byte(s)
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}
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return append(in, digest[:]...)
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}
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