///////////////////////////////////////////////////////
var key = "0@1Z2y3X4^5w6*7=8-9+";

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 = 4;
    var nCYCLELENGTH = 9;
    pg = new permutationGenerator(nNUMELEMENTS);
    var anCycle = new Array(nCYCLELENGTH);
    var npred = this.getHashValue();
    
    for (var i = 0; i < nCYCLELENGTH; i++) {
        npred = 11 * npred + 11;
        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(str){
    var sc = new SecureContext(str, key, false);
    sc.secure(key);
    
    return sc.strText;
}