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
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
// Copyright 2011 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview Implementation of HMAC in JavaScript.
*
* Usage:
* var hmac = new goog.crypt.Hmac(new goog.crypt.sha1(), key, 64);
* var digest = hmac.getHmac(bytes);
*
*/
goog.provide('goog.crypt.Hmac');
goog.require('goog.asserts');
goog.require('goog.crypt.Hash');
/**
* @constructor
* @param {!goog.crypt.Hash} hasher An object to serve as a hash function.
* @param {Array.<number>} key The secret key to use to calculate the hmac.
* Should be an array of not more than {@code blockSize} integers in
{0, 255}.
* @param {number=} opt_blockSize Optional. The block size {@code hasher} uses.
* If not specified, 16.
* @extends {goog.crypt.Hash}
*/
goog.crypt.Hmac = function(hasher, key, opt_blockSize) {
goog.base(this);
/**
* The underlying hasher to calculate hash.
*
* @type {!goog.crypt.Hash}
* @private
*/
this.hasher_ = hasher;
/**
* The block size.
*
* @type {number}
* @private
*/
this.blockSize_ = opt_blockSize || 16;
/**
* The outer padding array of hmac
*
* @type {!Array.<number>}
* @private
*/
this.keyO_ = new Array(this.blockSize_);
/**
* The inner padding array of hmac
*
* @type {!Array.<number>}
* @private
*/
this.keyI_ = new Array(this.blockSize_);
this.initialize_(key);
};
goog.inherits(goog.crypt.Hmac, goog.crypt.Hash);
/**
* Outer padding byte of HMAC algorith, per http://en.wikipedia.org/wiki/HMAC
*
* @type {number}
* @private
*/
goog.crypt.Hmac.OPAD_ = 0x5c;
/**
* Inner padding byte of HMAC algorith, per http://en.wikipedia.org/wiki/HMAC
*
* @type {number}
* @private
*/
goog.crypt.Hmac.IPAD_ = 0x36;
/**
* Initializes Hmac by precalculating the inner and outer paddings.
*
* @param {Array.<number>} key The secret key to use to calculate the hmac.
* Should be an array of not more than {@code blockSize} integers in
{0, 255}.
* @private
*/
goog.crypt.Hmac.prototype.initialize_ = function(key) {
if (key.length > this.blockSize_) {
this.hasher_.update(key);
key = this.hasher_.digest();
}
// Precalculate padded and xor'd keys.
var keyByte;
for (var i = 0; i < this.blockSize_; i++) {
if (i < key.length) {
keyByte = key[i];
} else {
keyByte = 0;
}
this.keyO_[i] = keyByte ^ goog.crypt.Hmac.OPAD_;
this.keyI_[i] = keyByte ^ goog.crypt.Hmac.IPAD_;
}
// Be ready for an immediate update.
this.hasher_.update(this.keyI_);
};
/** @override */
goog.crypt.Hmac.prototype.reset = function() {
this.hasher_.reset();
this.hasher_.update(this.keyI_);
};
/** @override */
goog.crypt.Hmac.prototype.update = function(bytes, opt_length) {
this.hasher_.update(bytes, opt_length);
};
/** @override */
goog.crypt.Hmac.prototype.digest = function() {
var temp = this.hasher_.digest();
this.hasher_.reset();
this.hasher_.update(this.keyO_);
this.hasher_.update(temp);
return this.hasher_.digest();
};
/**
* Calculates an HMAC for a given message.
*
* @param {Array.<number>} message An array of integers in {0, 255}.
* @return {Array} the digest of the given message.
*/
goog.crypt.Hmac.prototype.getHmac = function(message) {
this.reset();
this.update(message);
return this.digest();
};
|
