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