source: Dev/branches/rest-dojo-ui/client/dojox/sql/_crypto.js @ 256

dojo.provide("dojox.sql._crypto");
dojo.mixin(dojox.sql._crypto, {
        // summary: dojox.sql cryptography code
        // description:
        //      Taken from http://www.movable-type.co.uk/scripts/aes.html by
        //      Chris Veness (CLA signed); adapted for Dojo and Google Gears Worker Pool
        //      by Brad Neuberg, bkn3@columbia.edu
        //
        // _POOL_SIZE:
        //      Size of worker pool to create to help with crypto
        _POOL_SIZE: 100,

        encrypt: function(plaintext, password, callback){
                // summary:
                //      Use Corrected Block TEA to encrypt plaintext using password
                //      (note plaintext & password must be strings not string objects).
                //      Results will be returned to the 'callback' asychronously.
                this._initWorkerPool();

                var msg ={plaintext: plaintext, password: password};
                msg = dojo.toJson(msg);
                msg = "encr:" + String(msg);

                this._assignWork(msg, callback);
        },

        decrypt: function(ciphertext, password, callback){
                // summary:
                //      Use Corrected Block TEA to decrypt ciphertext using password
                //      (note ciphertext & password must be strings not string objects).
                //      Results will be returned to the 'callback' asychronously.
                this._initWorkerPool();

                var msg = {ciphertext: ciphertext, password: password};
                msg = dojo.toJson(msg);
                msg = "decr:" + String(msg);

                this._assignWork(msg, callback);
        },

        _initWorkerPool: function(){
                // bugs in Google Gears prevents us from dynamically creating
                // and destroying workers as we need them -- the worker
                // pool functionality stops working after a number of crypto
                // cycles (probably related to a memory leak in Google Gears).
                // this is too bad, since it results in much simpler code.

                // instead, we have to create a pool of workers and reuse them. we
                // keep a stack of 'unemployed' Worker IDs that are currently not working.
                // if a work request comes in, we pop off the 'unemployed' stack
                // and put them to work, storing them in an 'employed' hashtable,
                // keyed by their Worker ID with the value being the callback function
                // that wants the result. when an employed worker is done, we get
                // a message in our 'manager' which adds this worker back to the
                // unemployed stack and routes the result to the callback that
                // wanted it. if all the workers were employed in the past but
                // more work needed to be done (i.e. it's a tight labor pool ;)
                // then the work messages are pushed onto
                // a 'handleMessage' queue as an object tuple{msg: msg, callback: callback}

                if(!this._manager){
                        try{
                                this._manager = google.gears.factory.create("beta.workerpool", "1.0");
                                this._unemployed = [];
                                this._employed ={};
                                this._handleMessage = [];
                
                                var self = this;
                                this._manager.onmessage = function(msg, sender){
                                        // get the callback necessary to serve this result
                                        var callback = self._employed["_" + sender];
                        
                                        // make this worker unemployed
                                        self._employed["_" + sender] = undefined;
                                        self._unemployed.push("_" + sender);
                        
                                        // see if we need to assign new work
                                        // that was queued up needing to be done
                                        if(self._handleMessage.length){
                                                var handleMe = self._handleMessage.shift();
                                                self._assignWork(handleMe.msg, handleMe.callback);
                                        }
                        
                                        // return results
                                        callback(msg);
                                }
                        
                                var workerInit = "function _workerInit(){"
                                                                        + "gearsWorkerPool.onmessage = "
                                                                                + String(this._workerHandler)
                                                                        + ";"
                                                                + "}";
                
                                var code = workerInit + " _workerInit();";

                                // create our worker pool
                                for(var i = 0; i < this._POOL_SIZE; i++){
                                        this._unemployed.push("_" + this._manager.createWorker(code));
                                }
                        }catch(exp){
                                throw exp.message||exp;
                        }
                }
        },

        _assignWork: function(msg, callback){
                // can we immediately assign this work?
                if(!this._handleMessage.length && this._unemployed.length){
                        // get an unemployed worker
                        var workerID = this._unemployed.shift().substring(1); // remove _
        
                        // list this worker as employed
                        this._employed["_" + workerID] = callback;
        
                        // do the worke
                        this._manager.sendMessage(msg, parseInt(workerID,10));
                }else{
                        // we have to queue it up
                        this._handleMessage ={msg: msg, callback: callback};
                }
        },

        _workerHandler: function(msg, sender){
        
                /* Begin AES Implementation */
        
                /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
        
                // Sbox is pre-computed multiplicative inverse in GF(2^8) used in SubBytes and KeyExpansion [§5.1.1]
                var Sbox =      [0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76,
                                         0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0,
                                         0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15,
                                         0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75,
                                         0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84,
                                         0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf,
                                         0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8,
                                         0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2,
                                         0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73,
                                         0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb,
                                         0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79,
                                         0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08,
                                         0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a,
                                         0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e,
                                         0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf,
                                         0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16];

                // Rcon is Round Constant used for the Key Expansion [1st col is 2^(r-1) in GF(2^8)] [§5.2]
                var Rcon = [ [0x00, 0x00, 0x00, 0x00],
                                         [0x01, 0x00, 0x00, 0x00],
                                         [0x02, 0x00, 0x00, 0x00],
                                         [0x04, 0x00, 0x00, 0x00],
                                         [0x08, 0x00, 0x00, 0x00],
                                         [0x10, 0x00, 0x00, 0x00],
                                         [0x20, 0x00, 0x00, 0x00],
                                         [0x40, 0x00, 0x00, 0x00],
                                         [0x80, 0x00, 0x00, 0x00],
                                         [0x1b, 0x00, 0x00, 0x00],
                                         [0x36, 0x00, 0x00, 0x00] ];

                /*
                 * AES Cipher function: encrypt 'input' with Rijndael algorithm
                 *
                 *       takes   byte-array 'input' (16 bytes)
                 *                       2D byte-array key schedule 'w' (Nr+1 x Nb bytes)
                 *
                 *       applies Nr rounds (10/12/14) using key schedule w for 'add round key' stage
                 *
                 *       returns byte-array encrypted value (16 bytes)
                 */
                function Cipher(input, w) {        // main Cipher function [§5.1]
                  var Nb = 4;                           // block size (in words): no of columns in state (fixed at 4 for AES)
                  var Nr = w.length/Nb - 1; // no of rounds: 10/12/14 for 128/192/256-bit keys

                  var state = [[],[],[],[]];  // initialise 4xNb byte-array 'state' with input [§3.4]
                  for (var i=0; i<4*Nb; i++) state[i%4][Math.floor(i/4)] = input[i];

                  state = AddRoundKey(state, w, 0, Nb);

                  for (var round=1; round<Nr; round++) {
                        state = SubBytes(state, Nb);
                        state = ShiftRows(state, Nb);
                        state = MixColumns(state, Nb);
                        state = AddRoundKey(state, w, round, Nb);
                  }

                  state = SubBytes(state, Nb);
                  state = ShiftRows(state, Nb);
                  state = AddRoundKey(state, w, Nr, Nb);

                  var output = new Array(4*Nb);  // convert state to 1-d array before returning [§3.4]
                  for (var i=0; i<4*Nb; i++) output[i] = state[i%4][Math.floor(i/4)];
                  return output;
                }


                function SubBytes(s, Nb) {        // apply SBox to state S [§5.1.1]
                  for (var r=0; r<4; r++) {
                        for (var c=0; c<Nb; c++) s[r][c] = Sbox[s[r][c]];
                  }
                  return s;
                }


                function ShiftRows(s, Nb) {        // shift row r of state S left by r bytes [§5.1.2]
                  var t = new Array(4);
                  for (var r=1; r<4; r++) {
                        for (var c=0; c<4; c++) t[c] = s[r][(c+r)%Nb];  // shift into temp copy
                        for (var c=0; c<4; c++) s[r][c] = t[c];                 // and copy back
                  }                      // note that this will work for Nb=4,5,6, but not 7,8 (always 4 for AES):
                  return s;      // see fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.311.pdf
                }


                function MixColumns(s, Nb) {   // combine bytes of each col of state S [§5.1.3]
                  for (var c=0; c<4; c++) {
                        var a = new Array(4);  // 'a' is a copy of the current column from 's'
                        var b = new Array(4);  // 'b' is a•{02} in GF(2^8)
                        for (var i=0; i<4; i++) {
                          a[i] = s[i][c];
                          b[i] = s[i][c]&0x80 ? s[i][c]<<1 ^ 0x011b : s[i][c]<<1;
                        }
                        // a[n] ^ b[n] is a•{03} in GF(2^8)
                        s[0][c] = b[0] ^ a[1] ^ b[1] ^ a[2] ^ a[3]; // 2*a0 + 3*a1 + a2 + a3
                        s[1][c] = a[0] ^ b[1] ^ a[2] ^ b[2] ^ a[3]; // a0 * 2*a1 + 3*a2 + a3
                        s[2][c] = a[0] ^ a[1] ^ b[2] ^ a[3] ^ b[3]; // a0 + a1 + 2*a2 + 3*a3
                        s[3][c] = a[0] ^ b[0] ^ a[1] ^ a[2] ^ b[3]; // 3*a0 + a1 + a2 + 2*a3
                  }
                  return s;
                }


                function AddRoundKey(state, w, rnd, Nb) {  // xor Round Key into state S [§5.1.4]
                  for (var r=0; r<4; r++) {
                        for (var c=0; c<Nb; c++) state[r][c] ^= w[rnd*4+c][r];
                  }
                  return state;
                }


                function KeyExpansion(key) {  // generate Key Schedule (byte-array Nr+1 x Nb) from Key [§5.2]
                  var Nb = 4;                    // block size (in words): no of columns in state (fixed at 4 for AES)
                  var Nk = key.length/4  // key length (in words): 4/6/8 for 128/192/256-bit keys
                  var Nr = Nk + 6;               // no of rounds: 10/12/14 for 128/192/256-bit keys

                  var w = new Array(Nb*(Nr+1));
                  var temp = new Array(4);

                  for (var i=0; i<Nk; i++) {
                        var r = [key[4*i], key[4*i+1], key[4*i+2], key[4*i+3]];
                        w[i] = r;
                  }

                  for (var i=Nk; i<(Nb*(Nr+1)); i++) {
                        w[i] = new Array(4);
                        for (var t=0; t<4; t++) temp[t] = w[i-1][t];
                        if (i % Nk == 0) {
                          temp = SubWord(RotWord(temp));
                          for (var t=0; t<4; t++) temp[t] ^= Rcon[i/Nk][t];
                        } else if (Nk > 6 && i%Nk == 4) {
                          temp = SubWord(temp);
                        }
                        for (var t=0; t<4; t++) w[i][t] = w[i-Nk][t] ^ temp[t];
                  }

                  return w;
                }

                function SubWord(w) {    // apply SBox to 4-byte word w
                  for (var i=0; i<4; i++) w[i] = Sbox[w[i]];
                  return w;
                }

                function RotWord(w) {    // rotate 4-byte word w left by one byte
                  w[4] = w[0];
                  for (var i=0; i<4; i++) w[i] = w[i+1];
                  return w;
                }

                /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

                /*
                 * Use AES to encrypt 'plaintext' with 'password' using 'nBits' key, in 'Counter' mode of operation
                 *                                                       - see http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
                 *       for each block
                 *       - outputblock = cipher(counter, key)
                 *       - cipherblock = plaintext xor outputblock
                 */
                function AESEncryptCtr(plaintext, password, nBits) {
                  if (!(nBits==128 || nBits==192 || nBits==256)) return '';      // standard allows 128/192/256 bit keys

                  // for this example script, generate the key by applying Cipher to 1st 16/24/32 chars of password;
                  // for real-world applications, a more secure approach would be to hash the password e.g. with SHA-1
                  var nBytes = nBits/8;  // no bytes in key
                  var pwBytes = new Array(nBytes);
                  for (var i=0; i<nBytes; i++) pwBytes[i] = password.charCodeAt(i) & 0xff;

                  var key = Cipher(pwBytes, KeyExpansion(pwBytes));

                  key = key.concat(key.slice(0, nBytes-16));  // key is now 16/24/32 bytes long

                  // initialise counter block (NIST SP800-38A §B.2): millisecond time-stamp for nonce in 1st 8 bytes,
                  // block counter in 2nd 8 bytes
                  var blockSize = 16;  // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
                  var counterBlock = new Array(blockSize);      // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
                  var nonce = (new Date()).getTime();  // milliseconds since 1-Jan-1970

                  // encode nonce in two stages to cater for JavaScript 32-bit limit on bitwise ops
                  for (var i=0; i<4; i++) counterBlock[i] = (nonce >>> i*8) & 0xff;
                  for (var i=0; i<4; i++) counterBlock[i+4] = (nonce/0x100000000 >>> i*8) & 0xff;

                  // generate key schedule - an expansion of the key into distinct Key Rounds for each round
                  var keySchedule = KeyExpansion(key);

                  var blockCount = Math.ceil(plaintext.length/blockSize);
                  var ciphertext = new Array(blockCount);  // ciphertext as array of strings
 
                  for (var b=0; b<blockCount; b++) {
                        // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
                        // again done in two stages for 32-bit ops
                        for (var c=0; c<4; c++) counterBlock[15-c] = (b >>> c*8) & 0xff;
                        for (var c=0; c<4; c++) counterBlock[15-c-4] = (b/0x100000000 >>> c*8)

                        var cipherCntr = Cipher(counterBlock, keySchedule);      // -- encrypt counter block --

                        // calculate length of final block:
                        var blockLength = b<blockCount-1 ? blockSize : (plaintext.length-1)%blockSize+1;

                        var ct = '';
                        for (var i=0; i<blockLength; i++) {      // -- xor plaintext with ciphered counter byte-by-byte --
                          var plaintextByte = plaintext.charCodeAt(b*blockSize+i);
                          var cipherByte = plaintextByte ^ cipherCntr[i];
                          ct += String.fromCharCode(cipherByte);
                        }
                        // ct is now ciphertext for this block

                        ciphertext[b] = escCtrlChars(ct);  // escape troublesome characters in ciphertext
                  }

                  // convert the nonce to a string to go on the front of the ciphertext
                  var ctrTxt = '';
                  for (var i=0; i<8; i++) ctrTxt += String.fromCharCode(counterBlock[i]);
                  ctrTxt = escCtrlChars(ctrTxt);

                  // use '-' to separate blocks, use Array.join to concatenate arrays of strings for efficiency
                  return ctrTxt + '-' + ciphertext.join('-');
                }


                /*
                 * Use AES to decrypt 'ciphertext' with 'password' using 'nBits' key, in Counter mode of operation
                 *
                 *       for each block
                 *       - outputblock = cipher(counter, key)
                 *       - cipherblock = plaintext xor outputblock
                 */
                function AESDecryptCtr(ciphertext, password, nBits) {
                  if (!(nBits==128 || nBits==192 || nBits==256)) return '';      // standard allows 128/192/256 bit keys

                  var nBytes = nBits/8;  // no bytes in key
                  var pwBytes = new Array(nBytes);
                  for (var i=0; i<nBytes; i++) pwBytes[i] = password.charCodeAt(i) & 0xff;
                  var pwKeySchedule = KeyExpansion(pwBytes);
                  var key = Cipher(pwBytes, pwKeySchedule);
                  key = key.concat(key.slice(0, nBytes-16));  // key is now 16/24/32 bytes long

                  var keySchedule = KeyExpansion(key);

                  ciphertext = ciphertext.split('-');  // split ciphertext into array of block-length strings

                  // recover nonce from 1st element of ciphertext
                  var blockSize = 16;  // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
                  var counterBlock = new Array(blockSize);
                  var ctrTxt = unescCtrlChars(ciphertext[0]);
                  for (var i=0; i<8; i++) counterBlock[i] = ctrTxt.charCodeAt(i);

                  var plaintext = new Array(ciphertext.length-1);

                  for (var b=1; b<ciphertext.length; b++) {
                        // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
                        for (var c=0; c<4; c++) counterBlock[15-c] = ((b-1) >>> c*8) & 0xff;
                        for (var c=0; c<4; c++) counterBlock[15-c-4] = ((b/0x100000000-1) >>> c*8) & 0xff;

                        var cipherCntr = Cipher(counterBlock, keySchedule);      // encrypt counter block

                        ciphertext[b] = unescCtrlChars(ciphertext[b]);

                        var pt = '';
                        for (var i=0; i<ciphertext[b].length; i++) {
                          // -- xor plaintext with ciphered counter byte-by-byte --
                          var ciphertextByte = ciphertext[b].charCodeAt(i);
                          var plaintextByte = ciphertextByte ^ cipherCntr[i];
                          pt += String.fromCharCode(plaintextByte);
                        }
                        // pt is now plaintext for this block

                        plaintext[b-1] = pt;  // b-1 'cos no initial nonce block in plaintext
                  }

                  return plaintext.join('');
                }

                /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

                function escCtrlChars(str) {  // escape control chars which might cause problems handling ciphertext
                  return str.replace(/[\0\t\n\v\f\r\xa0!-]/g, function(c) { return '!' + c.charCodeAt(0) + '!'; });
                }  // \xa0 to cater for bug in Firefox; include '-' to leave it free for use as a block marker

                function unescCtrlChars(str) {  // unescape potentially problematic control characters
                  return str.replace(/!\d\d?\d?!/g, function(c) { return String.fromCharCode(c.slice(1,-1)); });
                }

                /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
        
                function encrypt(plaintext, password){
                        return AESEncryptCtr(plaintext, password, 256);
                }

                function decrypt(ciphertext, password){
                        return AESDecryptCtr(ciphertext, password, 256);
                }
        
                /* End AES Implementation */
        
                var cmd = msg.substr(0,4);
                var arg = msg.substr(5);
                if(cmd == "encr"){
                        arg = eval("(" + arg + ")");
                        var plaintext = arg.plaintext;
                        var password = arg.password;
                        var results = encrypt(plaintext, password);
                        gearsWorkerPool.sendMessage(String(results), sender);
                }else if(cmd == "decr"){
                        arg = eval("(" + arg + ")");
                        var ciphertext = arg.ciphertext;
                        var password = arg.password;
                        var results = decrypt(ciphertext, password);
                        gearsWorkerPool.sendMessage(String(results), sender);
                }
        }
});