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);
}