var md5 = require('create-hash/md5')
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var RIPEMD160 = require('ripemd160')
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var sha = require('sha.js')
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var Buffer = require('safe-buffer').Buffer
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var checkParameters = require('./precondition')
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var defaultEncoding = require('./default-encoding')
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var toBuffer = require('./to-buffer')
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var ZEROS = Buffer.alloc(128)
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var sizes = {
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md5: 16,
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sha1: 20,
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sha224: 28,
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sha256: 32,
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sha384: 48,
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sha512: 64,
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rmd160: 20,
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ripemd160: 20
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}
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function Hmac (alg, key, saltLen) {
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var hash = getDigest(alg)
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var blocksize = (alg === 'sha512' || alg === 'sha384') ? 128 : 64
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if (key.length > blocksize) {
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key = hash(key)
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} else if (key.length < blocksize) {
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key = Buffer.concat([key, ZEROS], blocksize)
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}
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var ipad = Buffer.allocUnsafe(blocksize + sizes[alg])
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var opad = Buffer.allocUnsafe(blocksize + sizes[alg])
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for (var i = 0; i < blocksize; i++) {
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ipad[i] = key[i] ^ 0x36
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opad[i] = key[i] ^ 0x5C
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}
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var ipad1 = Buffer.allocUnsafe(blocksize + saltLen + 4)
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ipad.copy(ipad1, 0, 0, blocksize)
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this.ipad1 = ipad1
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this.ipad2 = ipad
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this.opad = opad
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this.alg = alg
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this.blocksize = blocksize
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this.hash = hash
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this.size = sizes[alg]
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}
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Hmac.prototype.run = function (data, ipad) {
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data.copy(ipad, this.blocksize)
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var h = this.hash(ipad)
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h.copy(this.opad, this.blocksize)
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return this.hash(this.opad)
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}
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function getDigest (alg) {
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function shaFunc (data) {
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return sha(alg).update(data).digest()
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}
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function rmd160Func (data) {
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return new RIPEMD160().update(data).digest()
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}
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if (alg === 'rmd160' || alg === 'ripemd160') return rmd160Func
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if (alg === 'md5') return md5
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return shaFunc
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}
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function pbkdf2 (password, salt, iterations, keylen, digest) {
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checkParameters(iterations, keylen)
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password = toBuffer(password, defaultEncoding, 'Password')
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salt = toBuffer(salt, defaultEncoding, 'Salt')
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digest = digest || 'sha1'
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var hmac = new Hmac(digest, password, salt.length)
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var DK = Buffer.allocUnsafe(keylen)
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var block1 = Buffer.allocUnsafe(salt.length + 4)
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salt.copy(block1, 0, 0, salt.length)
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var destPos = 0
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var hLen = sizes[digest]
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var l = Math.ceil(keylen / hLen)
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for (var i = 1; i <= l; i++) {
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block1.writeUInt32BE(i, salt.length)
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var T = hmac.run(block1, hmac.ipad1)
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var U = T
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for (var j = 1; j < iterations; j++) {
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U = hmac.run(U, hmac.ipad2)
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for (var k = 0; k < hLen; k++) T[k] ^= U[k]
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}
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T.copy(DK, destPos)
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destPos += hLen
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}
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return DK
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}
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module.exports = pbkdf2
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