summaryrefslogtreecommitdiff
path: root/libgo/go/crypto/md4/md4.go
blob: e13c986e68637ee372b2243524db2d02ede4192f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
// 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.

// This package implements the MD4 hash algorithm as defined in RFC 1320.
package md4

import (
	"hash"
	"os"
)

// The size of an MD4 checksum in bytes.
const Size = 16

const (
	_Chunk = 64
	_Init0 = 0x67452301
	_Init1 = 0xEFCDAB89
	_Init2 = 0x98BADCFE
	_Init3 = 0x10325476
)

// digest represents the partial evaluation of a checksum.
type digest struct {
	s   [4]uint32
	x   [_Chunk]byte
	nx  int
	len uint64
}

func (d *digest) Reset() {
	d.s[0] = _Init0
	d.s[1] = _Init1
	d.s[2] = _Init2
	d.s[3] = _Init3
	d.nx = 0
	d.len = 0
}

// New returns a new hash.Hash computing the MD4 checksum.
func New() hash.Hash {
	d := new(digest)
	d.Reset()
	return d
}

func (d *digest) Size() int { return Size }

func (d *digest) Write(p []byte) (nn int, err os.Error) {
	nn = len(p)
	d.len += uint64(nn)
	if d.nx > 0 {
		n := len(p)
		if n > _Chunk-d.nx {
			n = _Chunk - d.nx
		}
		for i := 0; i < n; i++ {
			d.x[d.nx+i] = p[i]
		}
		d.nx += n
		if d.nx == _Chunk {
			_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.
	len := d.len
	var tmp [64]byte
	tmp[0] = 0x80
	if len%64 < 56 {
		d.Write(tmp[0 : 56-len%64])
	} else {
		d.Write(tmp[0 : 64+56-len%64])
	}

	// Length in bits.
	len <<= 3
	for i := uint(0); i < 8; i++ {
		tmp[i] = byte(len >> (8 * i))
	}
	d.Write(tmp[0:8])

	if d.nx != 0 {
		panic("d.nx != 0")
	}

	p := make([]byte, 16)
	j := 0
	for _, s := range d.s {
		p[j+0] = byte(s >> 0)
		p[j+1] = byte(s >> 8)
		p[j+2] = byte(s >> 16)
		p[j+3] = byte(s >> 24)
		j += 4
	}
	return p
}