<script language="javascript" type="text/javascript">
<!-- Original: Tomislav Sereg (tsereg@net.hr) -->
<!-- Web Site: http://www.inet.hr/~tsereg/jse -->
/* Visit http://www.yaldex.com/ for full source code
and get more free JavaScript, CSS and DHTML scripts! */
<!-- Begin
function doSecure() {
alert( 'JavaScript 1.2 or above required.' );
}
function doUnsecure() {
alert( 'JavaScript 1.2 or above required.' );
}

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

function doSecure() {
var sc = new SecureContext(document.frmSecurity.txtUnsecure.value,
document.frmSecurity.txtSign.value, document.frmSecurity.chkNewLines.checked);
sc.secure(document.frmSecurity.txtPassw.value);
document.frmSecurity.txtSecure.value = sc.strText;
document.frmSecurity.txtUnsecure.value = '';
}
function doUnsecure() {
var sc = new SecureContext(document.frmSecurity.txtSecure.value,
document.frmSecurity.txtSign.value, document.frmSecurity.chkNewLines.checked);
if (!sc.unsecure(document.frmSecurity.txtPassw.value))
alert('Invalid password used.');
document.frmSecurity.txtSecure.value = '';
document.frmSecurity.txtUnsecure.value = sc.strText;
}
// End -->
</script>
<center>
<table border=1>
<tr>
<td>Instructions:<br>
<ol>
<li>Input the password into the password field.</li>
<li>Optionally, input the signature into the signature field:</li>
<li>Input the plain text into the plain text field.</li>
<li>Press the SECURE button and observe the encrypted text.</li>
<li>Press the UNSECURE button and look at the decrypted text.</li>
<li>Check the 'new lines used' if you used new lines in the plain text</li>
</ol>
<form name=frmSecurity>
<br>Password: <input type=text name=txtPassw size=20 value="12345678">
Optional signature: <input type=text name=txtSign size=20><br>
<input type=checkbox name=chkNewLines value="1"> New lines used<br>
<table border=0>
<tr>
<td>Plain text:</td>
<td></td>
<td>Encrypted text:</td>
</tr>
<tr>
<td><textarea rows=4 name=txtUnsecure cols=20 wrap=virtual>the quick brown fox jumps over the lazy dog</textarea></td>
<td align=center><input type=button value="SECURE >>"
name=btnSecure onclick="doSecure()"><br>
<input type=button value="<< UNSECURE"
name=btnUnsecure onclick="doUnsecure()"></td>
<td><textarea rows=4 name=txtSecure cols=20 wrap=virtual></textarea></td>
</tr>
</table>
</form>
</td>
</tr>
</table>
</center>