aaac7fed
 liuqimichale
add
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'use strict'
var inherits = require('inherits')
var Legacy = require('./legacy')
var Base = require('cipher-base')
var Buffer = require('safe-buffer').Buffer
var md5 = require('create-hash/md5')
var RIPEMD160 = require('ripemd160')
var sha = require('sha.js')
var ZEROS = Buffer.alloc(128)
function Hmac (alg, key) {
Base.call(this, 'digest')
if (typeof key === 'string') {
key = Buffer.from(key)
}
var blocksize = (alg === 'sha512' || alg === 'sha384') ? 128 : 64
this._alg = alg
this._key = key
if (key.length > blocksize) {
var hash = alg === 'rmd160' ? new RIPEMD160() : sha(alg)
key = hash.update(key).digest()
} else if (key.length < blocksize) {
key = Buffer.concat([key, ZEROS], blocksize)
}
var ipad = this._ipad = Buffer.allocUnsafe(blocksize)
var opad = this._opad = Buffer.allocUnsafe(blocksize)
for (var i = 0; i < blocksize; i++) {
ipad[i] = key[i] ^ 0x36
opad[i] = key[i] ^ 0x5C
}
this._hash = alg === 'rmd160' ? new RIPEMD160() : sha(alg)
this._hash.update(ipad)
}
inherits(Hmac, Base)
Hmac.prototype._update = function (data) {
this._hash.update(data)
}
Hmac.prototype._final = function () {
var h = this._hash.digest()
var hash = this._alg === 'rmd160' ? new RIPEMD160() : sha(this._alg)
return hash.update(this._opad).update(h).digest()
}
module.exports = function createHmac (alg, key) {
alg = alg.toLowerCase()
if (alg === 'rmd160' || alg === 'ripemd160') {
return new Hmac('rmd160', key)
}
if (alg === 'md5') {
return new Legacy(md5, key)
}
return new Hmac(alg, key)
}
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