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Pragya Arya324337e2020-02-20 14:35:08 +05301// 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.
6//
7// Deprecated: MD4 is cryptographically broken and should should only be used
8// where compatibility with legacy systems, not security, is the goal. Instead,
9// use a secure hash like SHA-256 (from crypto/sha256).
10package md4 // import "golang.org/x/crypto/md4"
11
12import (
13 "crypto"
14 "hash"
15)
16
17func init() {
18 crypto.RegisterHash(crypto.MD4, New)
19}
20
21// The size of an MD4 checksum in bytes.
22const Size = 16
23
24// The blocksize of MD4 in bytes.
25const BlockSize = 64
26
27const (
28 _Chunk = 64
29 _Init0 = 0x67452301
30 _Init1 = 0xEFCDAB89
31 _Init2 = 0x98BADCFE
32 _Init3 = 0x10325476
33)
34
35// digest represents the partial evaluation of a checksum.
36type digest struct {
37 s [4]uint32
38 x [_Chunk]byte
39 nx int
40 len uint64
41}
42
43func (d *digest) Reset() {
44 d.s[0] = _Init0
45 d.s[1] = _Init1
46 d.s[2] = _Init2
47 d.s[3] = _Init3
48 d.nx = 0
49 d.len = 0
50}
51
52// New returns a new hash.Hash computing the MD4 checksum.
53func New() hash.Hash {
54 d := new(digest)
55 d.Reset()
56 return d
57}
58
59func (d *digest) Size() int { return Size }
60
61func (d *digest) BlockSize() int { return BlockSize }
62
63func (d *digest) Write(p []byte) (nn int, err error) {
64 nn = len(p)
65 d.len += uint64(nn)
66 if d.nx > 0 {
67 n := len(p)
68 if n > _Chunk-d.nx {
69 n = _Chunk - d.nx
70 }
71 for i := 0; i < n; i++ {
72 d.x[d.nx+i] = p[i]
73 }
74 d.nx += n
75 if d.nx == _Chunk {
76 _Block(d, d.x[0:])
77 d.nx = 0
78 }
79 p = p[n:]
80 }
81 n := _Block(d, p)
82 p = p[n:]
83 if len(p) > 0 {
84 d.nx = copy(d.x[:], p)
85 }
86 return
87}
88
89func (d0 *digest) Sum(in []byte) []byte {
90 // Make a copy of d0, so that caller can keep writing and summing.
91 d := new(digest)
92 *d = *d0
93
94 // Padding. Add a 1 bit and 0 bits until 56 bytes mod 64.
95 len := d.len
96 var tmp [64]byte
97 tmp[0] = 0x80
98 if len%64 < 56 {
99 d.Write(tmp[0 : 56-len%64])
100 } else {
101 d.Write(tmp[0 : 64+56-len%64])
102 }
103
104 // Length in bits.
105 len <<= 3
106 for i := uint(0); i < 8; i++ {
107 tmp[i] = byte(len >> (8 * i))
108 }
109 d.Write(tmp[0:8])
110
111 if d.nx != 0 {
112 panic("d.nx != 0")
113 }
114
115 for _, s := range d.s {
116 in = append(in, byte(s>>0))
117 in = append(in, byte(s>>8))
118 in = append(in, byte(s>>16))
119 in = append(in, byte(s>>24))
120 }
121 return in
122}