// 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;