// 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) {
		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.enc_b64 = RSAEncryptB64;