You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
58 lines
1.6 KiB
58 lines
1.6 KiB
2 years ago
|
/**
|
||
|
|
* Javascript implementation of mask generation function MGF1.
|
||
|
|
*
|
||
|
|
* @author Stefan Siegl
|
||
|
|
* @author Dave Longley
|
||
|
|
*
|
||
|
|
* Copyright (c) 2012 Stefan Siegl <stesie@brokenpipe.de>
|
||
|
|
* Copyright (c) 2014 Digital Bazaar, Inc.
|
||
|
|
*/
|
||
|
|
var forge = require('./forge');
|
||
|
|
require('./util');
|
||
|
|
|
||
|
|
forge.mgf = forge.mgf || {};
|
||
|
|
var mgf1 = module.exports = forge.mgf.mgf1 = forge.mgf1 = forge.mgf1 || {};
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Creates a MGF1 mask generation function object.
|
||
|
|
*
|
||
|
|
* @param md the message digest API to use (eg: forge.md.sha1.create()).
|
||
|
|
*
|
||
|
|
* @return a mask generation function object.
|
||
|
|
*/
|
||
|
|
mgf1.create = function(md) {
|
||
|
|
var mgf = {
|
||
|
|
/**
|
||
|
|
* Generate mask of specified length.
|
||
|
|
*
|
||
|
|
* @param {String} seed The seed for mask generation.
|
||
|
|
* @param maskLen Number of bytes to generate.
|
||
|
|
* @return {String} The generated mask.
|
||
|
|
*/
|
||
|
|
generate: function(seed, maskLen) {
|
||
|
|
/* 2. Let T be the empty octet string. */
|
||
|
|
var t = new forge.util.ByteBuffer();
|
||
|
|
|
||
|
|
/* 3. For counter from 0 to ceil(maskLen / hLen), do the following: */
|
||
|
|
var len = Math.ceil(maskLen / md.digestLength);
|
||
|
|
for(var i = 0; i < len; i++) {
|
||
|
|
/* a. Convert counter to an octet string C of length 4 octets */
|
||
|
|
var c = new forge.util.ByteBuffer();
|
||
|
|
c.putInt32(i);
|
||
|
|
|
||
|
|
/* b. Concatenate the hash of the seed mgfSeed and C to the octet
|
||
|
|
* string T: */
|
||
|
|
md.start();
|
||
|
|
md.update(seed + c.getBytes());
|
||
|
|
t.putBuffer(md.digest());
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Output the leading maskLen octets of T as the octet string mask. */
|
||
|
|
t.truncate(t.length() - maskLen);
|
||
|
|
return t.getBytes();
|
||
|
|
}
|
||
|
|
};
|
||
|
|
|
||
|
|
return mgf;
|
||
|
|
};
|