1// Copyright 2010 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// Package ripemd160 implements the RIPEMD-160 hash algorithm.
6package ripemd160 // import "golang.org/x/crypto/ripemd160"
7
8// RIPEMD-160 is designed by by Hans Dobbertin, Antoon Bosselaers, and Bart
9// Preneel with specifications available at:
10// http://homes.esat.kuleuven.be/~cosicart/pdf/AB-9601/AB-9601.pdf.
11
12import (
13	"crypto"
14	"hash"
15)
16
17func init() {
18	crypto.RegisterHash(crypto.RIPEMD160, New)
19}
20
21// The size of the checksum in bytes.
22const Size = 20
23
24// The block size of the hash algorithm in bytes.
25const BlockSize = 64
26
27const (
28	_s0 = 0x67452301
29	_s1 = 0xefcdab89
30	_s2 = 0x98badcfe
31	_s3 = 0x10325476
32	_s4 = 0xc3d2e1f0
33)
34
35// digest represents the partial evaluation of a checksum.
36type digest struct {
37	s  [5]uint32       // running context
38	x  [BlockSize]byte // temporary buffer
39	nx int             // index into x
40	tc uint64          // total count of bytes processed
41}
42
43func (d *digest) Reset() {
44	d.s[0], d.s[1], d.s[2], d.s[3], d.s[4] = _s0, _s1, _s2, _s3, _s4
45	d.nx = 0
46	d.tc = 0
47}
48
49// New returns a new hash.Hash computing the checksum.
50func New() hash.Hash {
51	result := new(digest)
52	result.Reset()
53	return result
54}
55
56func (d *digest) Size() int { return Size }
57
58func (d *digest) BlockSize() int { return BlockSize }
59
60func (d *digest) Write(p []byte) (nn int, err error) {
61	nn = len(p)
62	d.tc += uint64(nn)
63	if d.nx > 0 {
64		n := len(p)
65		if n > BlockSize-d.nx {
66			n = BlockSize - d.nx
67		}
68		for i := 0; i < n; i++ {
69			d.x[d.nx+i] = p[i]
70		}
71		d.nx += n
72		if d.nx == BlockSize {
73			_Block(d, d.x[0:])
74			d.nx = 0
75		}
76		p = p[n:]
77	}
78	n := _Block(d, p)
79	p = p[n:]
80	if len(p) > 0 {
81		d.nx = copy(d.x[:], p)
82	}
83	return
84}
85
86func (d0 *digest) Sum(in []byte) []byte {
87	// Make a copy of d0 so that caller can keep writing and summing.
88	d := *d0
89
90	// Padding.  Add a 1 bit and 0 bits until 56 bytes mod 64.
91	tc := d.tc
92	var tmp [64]byte
93	tmp[0] = 0x80
94	if tc%64 < 56 {
95		d.Write(tmp[0 : 56-tc%64])
96	} else {
97		d.Write(tmp[0 : 64+56-tc%64])
98	}
99
100	// Length in bits.
101	tc <<= 3
102	for i := uint(0); i < 8; i++ {
103		tmp[i] = byte(tc >> (8 * i))
104	}
105	d.Write(tmp[0:8])
106
107	if d.nx != 0 {
108		panic("d.nx != 0")
109	}
110
111	var digest [Size]byte
112	for i, s := range d.s {
113		digest[i*4] = byte(s)
114		digest[i*4+1] = byte(s >> 8)
115		digest[i*4+2] = byte(s >> 16)
116		digest[i*4+3] = byte(s >> 24)
117	}
118
119	return append(in, digest[:]...)
120}
121