1 | 'use strict'
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2 | var inherits = require('inherits')
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3 | var Legacy = require('./legacy')
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4 | var Base = require('cipher-base')
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5 | var Buffer = require('safe-buffer').Buffer
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6 | var md5 = require('create-hash/md5')
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7 | var RIPEMD160 = require('ripemd160')
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8 |
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9 | var sha = require('sha.js')
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10 |
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11 | var ZEROS = Buffer.alloc(128)
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12 |
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13 | function Hmac (alg, key) {
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14 | Base.call(this, 'digest')
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15 | if (typeof key === 'string') {
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16 | key = Buffer.from(key)
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17 | }
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18 |
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19 | var blocksize = (alg === 'sha512' || alg === 'sha384') ? 128 : 64
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20 |
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21 | this._alg = alg
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22 | this._key = key
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23 | if (key.length > blocksize) {
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24 | var hash = alg === 'rmd160' ? new RIPEMD160() : sha(alg)
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25 | key = hash.update(key).digest()
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26 | } else if (key.length < blocksize) {
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27 | key = Buffer.concat([key, ZEROS], blocksize)
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28 | }
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29 |
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30 | var ipad = this._ipad = Buffer.allocUnsafe(blocksize)
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31 | var opad = this._opad = Buffer.allocUnsafe(blocksize)
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32 |
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33 | for (var i = 0; i < blocksize; i++) {
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34 | ipad[i] = key[i] ^ 0x36
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35 | opad[i] = key[i] ^ 0x5C
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36 | }
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37 | this._hash = alg === 'rmd160' ? new RIPEMD160() : sha(alg)
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38 | this._hash.update(ipad)
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39 | }
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40 |
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41 | inherits(Hmac, Base)
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42 |
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43 | Hmac.prototype._update = function (data) {
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44 | this._hash.update(data)
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45 | }
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46 |
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47 | Hmac.prototype._final = function () {
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48 | var h = this._hash.digest()
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49 | var hash = this._alg === 'rmd160' ? new RIPEMD160() : sha(this._alg)
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50 | return hash.update(this._opad).update(h).digest()
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51 | }
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52 |
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53 | module.exports = function createHmac (alg, key) {
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54 | alg = alg.toLowerCase()
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55 | if (alg === 'rmd160' || alg === 'ripemd160') {
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56 | return new Hmac('rmd160', key)
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57 | }
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58 | if (alg === 'md5') {
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59 | return new Legacy(md5, key)
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60 | }
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61 | return new Hmac(alg, key)
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62 | }
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