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rsa.js
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rsa.js
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// Depends on jsbn.js and rng.js
// Version 1.1: support utf-8 encoding in pkcs1pad2
// convert a (hex) string to a bignum object
function parseBigInt(str, r) {
return new BigInteger(str, r);
}
function linebrk(s, n) {
var ret = "";
var i = 0;
while (i + n < s.length) {
ret += s.substring(i, i + n) + "\n";
i += n;
}
return ret + s.substring(i, s.length);
}
function byte2Hex(b) {
if (b < 0x10)
return "0" + b.toString(16);
else
return b.toString(16);
}
// PKCS#1 (type 2, random) pad input string s to n bytes, and return a bigint
function pkcs1pad2(s, n) {
if (n < s.length + 11) { // TODO: fix for utf-8
alert("Message too long for RSA");
return null;
}
var ba = new Array();
var i = s.length - 1;
while (i >= 0 && n > 0) {
var c = s.charCodeAt(i--);
if (c < 128) { // encode using utf-8
ba[--n] = c;
}
else if ((c > 127) && (c < 2048)) {
ba[--n] = (c & 63) | 128;
ba[--n] = (c >> 6) | 192;
}
else {
ba[--n] = (c & 63) | 128;
ba[--n] = ((c >> 6) & 63) | 128;
ba[--n] = (c >> 12) | 224;
}
}
ba[--n] = 0;
var rng = new SecureRandom();
var x = new Array();
while (n > 2) { // random non-zero pad
x[0] = 0;
while (x[0] == 0) rng.nextBytes(x);
ba[--n] = x[0];
}
ba[--n] = 2;
ba[--n] = 0;
return new BigInteger(ba);
}
// "empty" RSA key constructor
function RSAKey() {
this.n = null;
this.e = 0;
this.d = null;
this.p = null;
this.q = null;
this.dmp1 = null;
this.dmq1 = null;
this.coeff = null;
}
// Set the public key fields N and e from hex strings
function RSASetPublic(N, E) {
if (N != null && E != null && N.length > 0 && E.length > 0) {
this.n = parseBigInt(N, 16);
this.e = parseInt(E, 16);
}
else
alert("Invalid RSA public key");
}
// Perform raw public operation on "x": return x^e (mod n)
function RSADoPublic(x) {
return x.modPowInt(this.e, this.n);
}
// Return the PKCS#1 RSA encryption of "text" as an even-length hex string
function RSAEncrypt(text) {
var m = pkcs1pad2(text, (this.n.bitLength() + 7) >> 3);
if (m == null) return null;
var c = this.doPublic(m);
if (c == null) return null;
var h = c.toString(16);
if ((h.length & 1) == 0) return h; else return "0" + h;
}
// Return the PKCS#1 RSA encryption of "text" as a Base64-encoded string
//function RSAEncryptB64(text) {
// var h = this.encrypt(text);
// if(h) return hex2b64(h); else return null;
//}
// protected
RSAKey.prototype.doPublic = RSADoPublic;
// public
RSAKey.prototype.setPublic = RSASetPublic;
RSAKey.prototype.encrypt = RSAEncrypt;
//RSAKey.prototype.encrypt_b64 = RSAEncryptB64;