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// Copyright 2010 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.
// This package implements the RIPEMD-160 hash algorithm.
package ripemd160
// RIPEMD-160 is designed by by Hans Dobbertin, Antoon Bosselaers, and Bart
// Preneel with specifications available at:
// http://homes.esat.kuleuven.be/~cosicart/pdf/AB-9601/AB-9601.pdf.
import (
"hash"
"os"
)
// The size of the checksum in bytes.
const Size = 20
// The block size of the hash algorithm in bytes.
const BlockSize = 64
const (
_s0 = 0x67452301
_s1 = 0xefcdab89
_s2 = 0x98badcfe
_s3 = 0x10325476
_s4 = 0xc3d2e1f0
)
// digest represents the partial evaluation of a checksum.
type digest struct {
s [5]uint32 // running context
x [BlockSize]byte // temporary buffer
nx int // index into x
tc uint64 // total count of bytes processed
}
func (d *digest) Reset() {
d.s[0], d.s[1], d.s[2], d.s[3], d.s[4] = _s0, _s1, _s2, _s3, _s4
d.nx = 0
d.tc = 0
}
// New returns a new hash.Hash computing the checksum.
func New() hash.Hash {
result := new(digest)
result.Reset()
return result
}
func (d *digest) Size() int { return Size }
func (d *digest) Write(p []byte) (nn int, err os.Error) {
nn = len(p)
d.tc += uint64(nn)
if d.nx > 0 {
n := len(p)
if n > BlockSize-d.nx {
n = BlockSize - d.nx
}
for i := 0; i < n; i++ {
d.x[d.nx+i] = p[i]
}
d.nx += n
if d.nx == BlockSize {
_Block(d, d.x[0:])
d.nx = 0
}
p = p[n:]
}
n := _Block(d, p)
p = p[n:]
if len(p) > 0 {
d.nx = copy(d.x[:], p)
}
return
}
func (d0 *digest) Sum() []byte {
// Make a copy of d0 so that caller can keep writing and summing.
d := new(digest)
*d = *d0
// Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
tc := d.tc
var tmp [64]byte
tmp[0] = 0x80
if tc%64 < 56 {
d.Write(tmp[0 : 56-tc%64])
} else {
d.Write(tmp[0 : 64+56-tc%64])
}
// Length in bits.
tc <<= 3
for i := uint(0); i < 8; i++ {
tmp[i] = byte(tc >> (8 * i))
}
d.Write(tmp[0:8])
if d.nx != 0 {
panic("d.nx != 0")
}
p := make([]byte, 20)
j := 0
for _, s := range d.s {
p[j], p[j+1], p[j+2], p[j+3] = byte(s), byte(s>>8), byte(s>>16), byte(s>>24)
j += 4
}
return p
}
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