aaac7fed
 liuqimichale
add
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'use strict';
var utils = require('./utils');
var assert = require('minimalistic-assert');
function Hmac(hash, key, enc) {
if (!(this instanceof Hmac))
return new Hmac(hash, key, enc);
this.Hash = hash;
this.blockSize = hash.blockSize / 8;
this.outSize = hash.outSize / 8;
this.inner = null;
this.outer = null;
this._init(utils.toArray(key, enc));
}
module.exports = Hmac;
Hmac.prototype._init = function init(key) {
// Shorten key, if needed
if (key.length > this.blockSize)
key = new this.Hash().update(key).digest();
assert(key.length <= this.blockSize);
// Add padding to key
for (var i = key.length; i < this.blockSize; i++)
key.push(0);
for (i = 0; i < key.length; i++)
key[i] ^= 0x36;
this.inner = new this.Hash().update(key);
// 0x36 ^ 0x5c = 0x6a
for (i = 0; i < key.length; i++)
key[i] ^= 0x6a;
this.outer = new this.Hash().update(key);
};
Hmac.prototype.update = function update(msg, enc) {
this.inner.update(msg, enc);
return this;
};
Hmac.prototype.digest = function digest(enc) {
this.outer.update(this.inner.digest());
return this.outer.digest(enc);
};
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