function alertTest(){
	alert('it works!');
}

function encrypt(plainText) {
	//alert('plainText=' + plainText); 
	var sc = new SecureContext(plainText, 
	'', false);
	sc.secure('12345678');//this is the key 
	//alert('sc.strText=' + sc.strText);
	return sc.strText;
}

function decrypt(enctyptedText) {
	var sc = new SecureContext(enctyptedText, 
		'', false);
	if (!sc.unsecure('12345678')) 
		alert('Invalid password used.');
	return sc.strText;
}	

function permutationGenerator(nNumElements) {
	this.nNumElements     = nNumElements;
	this.antranspositions = new Array;
	var k = 0;
	for (i = 0; i < nNumElements - 1; i++)
	for (j = i + 1; j < nNumElements; j++)
		this.antranspositions[ k++ ] = ( i << 8 ) | j;
	// keep two positions as lo and hi byte!
	this.nNumtranspositions = k;
	this.fromCycle = permutationGenerator_fromCycle;
}

function permutationGenerator_fromCycle(anCycle) {
	var anpermutation = new Array(this.nNumElements);
	for (var i = 0; i < this.nNumElements; i++) anpermutation[i] = i;
	for (var i = 0; i < anCycle.length; i++) {
		var nT = this.antranspositions[anCycle[i]];
		var n1 = nT & 255;
		var n2 = (nT >> 8) & 255;
		nT = anpermutation[n1];
		anpermutation[n1] = anpermutation[n2];
		anpermutation[n2] = nT;
	}
	return anpermutation;
}

function passwordFunction(strpasswd) {
	this.strpasswd = strpasswd;
	this.getHashValue   = password_getHashValue;
	this.getpermutation = password_getpermutation;
}

function password_getHashValue() {
	var m = 907633409;
	var a = 65599;
	var h = 0;
	for (var i = 0; i < this.strpasswd.length; i++) 
	h = (h % m) * a + this.strpasswd.charCodeAt(i);
	return h;
}

function password_getpermutation() {
	var nNUMELEMENTS = 13;
	var nCYCLELENGTH = 21;
	pg = new permutationGenerator(nNUMELEMENTS);
	var anCycle = new Array(nCYCLELENGTH);
	var npred   = this.getHashValue();
	for (var i = 0; i < nCYCLELENGTH; i++) {
		npred = 314159269 * npred + 907633409;
		anCycle[i] = npred % pg.nNumtranspositions;
		}
	return pg.fromCycle(anCycle);
}

function SecureContext(strText, strSignature, bEscape) {
	//alert('strText=' + strText);
	this.strSIGNATURE = strSignature || '';
	this.bESCApE      = bEscape || false;
	this.strText = strText;
	this.escape        = SecureContext_escape;
	this.unescape      = SecureContext_unescape;
	this.transliterate = SecureContext_transliterate;
	this.encypher      = SecureContext_encypher;
	this.decypher      = SecureContext_decypher;
	this.sign          = SecureContext_sign;
	this.unsign        = SecureContext_unsign;
	this.secure   = SecureContext_secure;
	this.unsecure = SecureContext_unsecure;
}

function SecureContext_escape(strToEscape) {
	var strEscaped = '';
	for (var i = 0; i < strToEscape.length; i++) {
		var chT = strToEscape.charAt( i );
		switch(chT) {
		case '\r': strEscaped += '\\r'; break;
		case '\n': strEscaped += '\\n'; break;
		case '\\': strEscaped += '\\\\'; break;
		default: strEscaped += chT;
	   }
	}
	return strEscaped;
}

function SecureContext_unescape(strToUnescape) {
	var strUnescaped = '';
	var i = 0;
	while (i < strToUnescape.length) {
		var chT = strToUnescape.charAt(i++);
		if ('\\' == chT) {
			chT = strToUnescape.charAt( i++ );
			switch( chT ) {
				case 'r': strUnescaped += '\r'; break;
				case 'n': strUnescaped += '\n'; break;
				case '\\': strUnescaped += '\\'; break;
				default: // not possible
			}
		}
		else strUnescaped += chT;
	}
	return strUnescaped;
}
function SecureContext_transliterate(btransliterate) {
	var strDest = '';
	
	var nTextIter  = 0;
	var nTexttrail = 0;
	
	while (nTextIter < this.strText.length) {
	var strRun = '';
	var cSkipped   = 0;
	while (cSkipped < 7 && nTextIter < this.strText.length) {
		var chT = this.strText.charAt(nTextIter++);
		if (-1 == strRun.indexOf(chT)) {
			strRun += chT;
			cSkipped = 0;
		}
		else cSkipped++;
	}
	while (nTexttrail < nTextIter) {
		var nRunIdx = strRun.indexOf(this.strText.charAt(nTexttrail++));
		if (btransliterate) {
			nRunIdx++
			if (nRunIdx == strRun.length) nRunIdx = 0;
			}
			else {
				nRunIdx--;
				if (nRunIdx == -1) nRunIdx += strRun.length;
			}
			strDest += strRun.charAt(nRunIdx);
	   }
	}
	this.strText = strDest;
}

function SecureContext_encypher(anperm) {
	var strEncyph = '';
	var nCols     = anperm.length;
	var nRows     = this.strText.length / nCols;
	for (var i = 0; i < nCols; i++) {
		var k = anperm[ i ];
		for (var j = 0; j < nRows; j++) {
			strEncyph += this.strText.charAt(k);
			k         += nCols;
		}
	}
	this.strText = strEncyph;
}

function SecureContext_decypher(anperm) {
	var nRows    = anperm.length;
	var nCols    = this.strText.length / nRows;
	var anRowOfs = new Array;
	for (var i = 0 ; i < nRows; i++) anRowOfs[ anperm[ i ] ] = i * nCols;
	var strplain = '';
	for (var i = 0; i < nCols; i++) {
		for (var j = 0; j < nRows; j++)
		strplain += this.strText.charAt(anRowOfs[ j ] + i);
	}
	this.strText = strplain;
}

function SecureContext_sign(nCols) {
	if (this.bESCApE) {
		this.strText      = this.escape(this.strText);
		this.strSIGNATURE = this.escape(this.strSIGNATURE);
	}
	var nTextLen     = this.strText.length + this.strSIGNATURE.length;
	var nMissingCols = nCols - (nTextLen % nCols);
	var strpadding   = '';  
	if (nMissingCols < nCols)
	for (var i = 0; i < nMissingCols; i++) strpadding += ' ';
	var x = this.strText.length;
	this.strText +=  strpadding + this.strSIGNATURE;
}

function SecureContext_unsign(nCols) {
	if (this.bESCApE) {
		this.strText      = this.unescape(this.strText);
		this.strSIGNATURE = this.unescape(this.strSIGNATURE);
	}
	if ('' == this.strSIGNATURE) return true;
	var nTextLen = this.strText.lastIndexOf(this.strSIGNATURE);
	if (-1 == nTextLen) return false;
	this.strText = this.strText.substr(0, nTextLen);
	return true;
}

function SecureContext_secure(strpasswd) {
	var passwd = new passwordFunction(strpasswd);
	var anperm   = passwd.getpermutation()
	this.sign(anperm.length);
	this.transliterate(true);
	this.encypher(anperm);
}

function SecureContext_unsecure(strpasswd) {
	var passwd = new passwordFunction(strpasswd);
	var anperm = passwd.getpermutation()
	this.decypher(anperm);
	this.transliterate(false);
	return this.unsign(anperm.length);
}