aaac7fed
 liuqimichale
add
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'use strict'
var inherits = require('inherits')
var Buffer = require('safe-buffer').Buffer
var Base = require('cipher-base')
var ZEROS = Buffer.alloc(128)
var blocksize = 64
function Hmac (alg, key) {
Base.call(this, 'digest')
if (typeof key === 'string') {
key = Buffer.from(key)
}
this._alg = alg
this._key = key
if (key.length > blocksize) {
key = alg(key)
} 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 = [ipad]
}
inherits(Hmac, Base)
Hmac.prototype._update = function (data) {
this._hash.push(data)
}
Hmac.prototype._final = function () {
var h = this._alg(Buffer.concat(this._hash))
return this._alg(Buffer.concat([this._opad, h]))
}
module.exports = Hmac
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