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Side by Side Diff: md4/md4.go

Issue 5564059: code review 5564059: go.crypto: initial code (Closed)
Patch Set: diff -r b50a7fb49394 https://code.google.com/p/go.crypto Created 12 years, 2 months ago
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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.
6 package md4
7
8 import (
9 "crypto"
10 "hash"
11 )
12
13 func init() {
14 crypto.RegisterHash(crypto.MD4, New)
15 }
16
17 // The size of an MD4 checksum in bytes.
18 const Size = 16
19
20 // The blocksize of MD4 in bytes.
21 const BlockSize = 64
22
23 const (
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.
32 type digest struct {
33 s [4]uint32
34 x [_Chunk]byte
35 nx int
36 len uint64
37 }
38
39 func (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.
49 func New() hash.Hash {
50 d := new(digest)
51 d.Reset()
52 return d
53 }
54
55 func (d *digest) Size() int { return Size }
56
57 func (d *digest) BlockSize() int { return BlockSize }
58
59 func (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
85 func (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 }
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