aaac7fed
 liuqimichale
add
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'use strict';
var hash = require('hash.js');
var utils = require('minimalistic-crypto-utils');
var assert = require('minimalistic-assert');
function HmacDRBG(options) {
if (!(this instanceof HmacDRBG))
return new HmacDRBG(options);
this.hash = options.hash;
this.predResist = !!options.predResist;
this.outLen = this.hash.outSize;
this.minEntropy = options.minEntropy || this.hash.hmacStrength;
this._reseed = null;
this.reseedInterval = null;
this.K = null;
this.V = null;
var entropy = utils.toArray(options.entropy, options.entropyEnc || 'hex');
var nonce = utils.toArray(options.nonce, options.nonceEnc || 'hex');
var pers = utils.toArray(options.pers, options.persEnc || 'hex');
assert(entropy.length >= (this.minEntropy / 8),
'Not enough entropy. Minimum is: ' + this.minEntropy + ' bits');
this._init(entropy, nonce, pers);
}
module.exports = HmacDRBG;
HmacDRBG.prototype._init = function init(entropy, nonce, pers) {
var seed = entropy.concat(nonce).concat(pers);
this.K = new Array(this.outLen / 8);
this.V = new Array(this.outLen / 8);
for (var i = 0; i < this.V.length; i++) {
this.K[i] = 0x00;
this.V[i] = 0x01;
}
this._update(seed);
this._reseed = 1;
this.reseedInterval = 0x1000000000000; // 2^48
};
HmacDRBG.prototype._hmac = function hmac() {
return new hash.hmac(this.hash, this.K);
};
HmacDRBG.prototype._update = function update(seed) {
var kmac = this._hmac()
.update(this.V)
.update([ 0x00 ]);
if (seed)
kmac = kmac.update(seed);
this.K = kmac.digest();
this.V = this._hmac().update(this.V).digest();
if (!seed)
return;
this.K = this._hmac()
.update(this.V)
.update([ 0x01 ])
.update(seed)
.digest();
this.V = this._hmac().update(this.V).digest();
};
HmacDRBG.prototype.reseed = function reseed(entropy, entropyEnc, add, addEnc) {
// Optional entropy enc
if (typeof entropyEnc !== 'string') {
addEnc = add;
add = entropyEnc;
entropyEnc = null;
}
entropy = utils.toArray(entropy, entropyEnc);
add = utils.toArray(add, addEnc);
assert(entropy.length >= (this.minEntropy / 8),
'Not enough entropy. Minimum is: ' + this.minEntropy + ' bits');
this._update(entropy.concat(add || []));
this._reseed = 1;
};
HmacDRBG.prototype.generate = function generate(len, enc, add, addEnc) {
if (this._reseed > this.reseedInterval)
throw new Error('Reseed is required');
// Optional encoding
if (typeof enc !== 'string') {
addEnc = add;
add = enc;
enc = null;
}
// Optional additional data
if (add) {
add = utils.toArray(add, addEnc || 'hex');
this._update(add);
}
var temp = [];
while (temp.length < len) {
this.V = this._hmac().update(this.V).digest();
temp = temp.concat(this.V);
}
var res = temp.slice(0, len);
this._update(add);
this._reseed++;
return utils.encode(res, enc);
};
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