108 lines
2.5 KiB
JavaScript
108 lines
2.5 KiB
JavaScript
var parseKeys = require('parse-asn1');
|
|
var mgf = require('./mgf');
|
|
var xor = require('./xor');
|
|
var bn = require('bn.js');
|
|
var crt = require('browserify-rsa');
|
|
var createHash = require('create-hash');
|
|
var withPublic = require('./withPublic');
|
|
module.exports = function privateDecrypt(private_key, enc, reverse) {
|
|
var padding;
|
|
if (private_key.padding) {
|
|
padding = private_key.padding;
|
|
} else if (reverse) {
|
|
padding = 1;
|
|
} else {
|
|
padding = 4;
|
|
}
|
|
|
|
var key = parseKeys(private_key);
|
|
var k = key.modulus.byteLength();
|
|
if (enc.length > k || new bn(enc).cmp(key.modulus) >= 0) {
|
|
throw new Error('decryption error');
|
|
}
|
|
var msg;
|
|
if (reverse) {
|
|
msg = withPublic(new bn(enc), key);
|
|
} else {
|
|
msg = crt(enc, key);
|
|
}
|
|
var zBuffer = new Buffer(k - msg.length);
|
|
zBuffer.fill(0);
|
|
msg = Buffer.concat([zBuffer, msg], k);
|
|
if (padding === 4) {
|
|
return oaep(key, msg);
|
|
} else if (padding === 1) {
|
|
return pkcs1(key, msg, reverse);
|
|
} else if (padding === 3) {
|
|
return msg;
|
|
} else {
|
|
throw new Error('unknown padding');
|
|
}
|
|
};
|
|
|
|
function oaep(key, msg){
|
|
var n = key.modulus;
|
|
var k = key.modulus.byteLength();
|
|
var mLen = msg.length;
|
|
var iHash = createHash('sha1').update(new Buffer('')).digest();
|
|
var hLen = iHash.length;
|
|
var hLen2 = 2 * hLen;
|
|
if (msg[0] !== 0) {
|
|
throw new Error('decryption error');
|
|
}
|
|
var maskedSeed = msg.slice(1, hLen + 1);
|
|
var maskedDb = msg.slice(hLen + 1);
|
|
var seed = xor(maskedSeed, mgf(maskedDb, hLen));
|
|
var db = xor(maskedDb, mgf(seed, k - hLen - 1));
|
|
if (compare(iHash, db.slice(0, hLen))) {
|
|
throw new Error('decryption error');
|
|
}
|
|
var i = hLen;
|
|
while (db[i] === 0) {
|
|
i++;
|
|
}
|
|
if (db[i++] !== 1) {
|
|
throw new Error('decryption error');
|
|
}
|
|
return db.slice(i);
|
|
}
|
|
|
|
function pkcs1(key, msg, reverse){
|
|
var p1 = msg.slice(0, 2);
|
|
var i = 2;
|
|
var status = 0;
|
|
while (msg[i++] !== 0) {
|
|
if (i >= msg.length) {
|
|
status++;
|
|
break;
|
|
}
|
|
}
|
|
var ps = msg.slice(2, i - 1);
|
|
var p2 = msg.slice(i - 1, i);
|
|
|
|
if ((p1.toString('hex') !== '0002' && !reverse) || (p1.toString('hex') !== '0001' && reverse)){
|
|
status++;
|
|
}
|
|
if (ps.length < 8) {
|
|
status++;
|
|
}
|
|
if (status) {
|
|
throw new Error('decryption error');
|
|
}
|
|
return msg.slice(i);
|
|
}
|
|
function compare(a, b){
|
|
a = new Buffer(a);
|
|
b = new Buffer(b);
|
|
var dif = 0;
|
|
var len = a.length;
|
|
if (a.length !== b.length) {
|
|
dif++;
|
|
len = Math.min(a.length, b.length);
|
|
}
|
|
var i = -1;
|
|
while (++i < len) {
|
|
dif += (a[i] ^ b[i]);
|
|
}
|
|
return dif;
|
|
} |