1// Copyright 2009 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 md4 implements the MD4 hash algorithm as defined in RFC 1320.
6package md4 // import "golang.org/x/crypto/md4"
7
8import (
9	"crypto"
10	"hash"
11)
12
13func init() {
14	crypto.RegisterHash(crypto.MD4, New)
15}
16
17// The size of an MD4 checksum in bytes.
18const Size = 16
19
20// The blocksize of MD4 in bytes.
21const BlockSize = 64
22
23const (
24	_Chunk = 64
25	_Init0 = 0x67452301
26	_Init1 = 0xEFCDAB89
27	_Init2 = 0x98BADCFE
28	_Init3 = 0x10325476
29)
30
31// digest represents the partial evaluation of a checksum.
32type digest struct {
33	s   [4]uint32
34	x   [_Chunk]byte
35	nx  int
36	len uint64
37}
38
39func (d *digest) Reset() {
40	d.s[0] = _Init0
41	d.s[1] = _Init1
42	d.s[2] = _Init2
43	d.s[3] = _Init3
44	d.nx = 0
45	d.len = 0
46}
47
48// New returns a new hash.Hash computing the MD4 checksum.
49func New() hash.Hash {
50	d := new(digest)
51	d.Reset()
52	return d
53}
54
55func (d *digest) Size() int { return Size }
56
57func (d *digest) BlockSize() int { return BlockSize }
58
59func (d *digest) Write(p []byte) (nn int, err error) {
60	nn = len(p)
61	d.len += uint64(nn)
62	if d.nx > 0 {
63		n := len(p)
64		if n > _Chunk-d.nx {
65			n = _Chunk - d.nx
66		}
67		for i := 0; i < n; i++ {
68			d.x[d.nx+i] = p[i]
69		}
70		d.nx += n
71		if d.nx == _Chunk {
72			_Block(d, d.x[0:])
73			d.nx = 0
74		}
75		p = p[n:]
76	}
77	n := _Block(d, p)
78	p = p[n:]
79	if len(p) > 0 {
80		d.nx = copy(d.x[:], p)
81	}
82	return
83}
84
85func (d0 *digest) Sum(in []byte) []byte {
86	// Make a copy of d0, so that caller can keep writing and summing.
87	d := new(digest)
88	*d = *d0
89
90	// Padding.  Add a 1 bit and 0 bits until 56 bytes mod 64.
91	len := d.len
92	var tmp [64]byte
93	tmp[0] = 0x80
94	if len%64 < 56 {
95		d.Write(tmp[0 : 56-len%64])
96	} else {
97		d.Write(tmp[0 : 64+56-len%64])
98	}
99
100	// Length in bits.
101	len <<= 3
102	for i := uint(0); i < 8; i++ {
103		tmp[i] = byte(len >> (8 * i))
104	}
105	d.Write(tmp[0:8])
106
107	if d.nx != 0 {
108		panic("d.nx != 0")
109	}
110
111	for _, s := range d.s {
112		in = append(in, byte(s>>0))
113		in = append(in, byte(s>>8))
114		in = append(in, byte(s>>16))
115		in = append(in, byte(s>>24))
116	}
117	return in
118}
119