/*
 * Usage:
 *	aesdata = encrypt_aes_chain(hexkey, hexiv, rawdata);
 *	rawdata = decrypt_aes(hexkey, hexiv, aesdata);
 *	hexkey must be a 128bit integer encoded in hexidecimal (16bytes of ascii characters 0-F)
 *	hexiv must be a 128bit integer encoded in hexidecimal (16bytes of ascii characters 0-F)
 */

//
// AES routines from http://www.cs.eku.edu/faculty/styer/460/Encrypt/JS-AES-Chain.html
//
/*
 * License
 *
 * unknown
 */
// sample key to expand:
//      2b 7e 15 16 28 ae d2 a6 ab f7 15 88 09 cf 4f 3c
// sample data:
//      32 43 f6 a8 88 5a 30 8d 31 31 98 a2 e0 37 07 34
// output:
//      39 25 84 1d 02 dc 09 fb dc 11 85 97 19 6a 0b 32

// sample key/data:
// PLAINTEXT: 00112233445566778899aabbccddeeff
// KEY:       000102030405060708090a0b0c0d0e0f
// OUTPUT:    69c4e0d86a7b0430d8cdb78070b4c55a// Rewritten by E.K.
//	only support output feedback
//	allows unlimited message length  kVCQgqTSOuDNnQ1jQ6WCcg==

// convert a 8-bit value to a string
function cvt_hex8( val )
{
   var vh = (val>>>4)&0x0f;
   return vh.toString(16) + (val&0x0f).toString(16);
}

// convert a 32-bit value to a 8-char hex string
function cvt_hex32( val )
{
   var str="";
   var i;
   var v;

   for( i=7; i>=0; i-- )
   {
      v = (val>>>(i*4))&0x0f;
      str += v.toString(16);
   }
   return str;
}

// convert a two-digit hex value to a number
function cvt_byte( str )
{
  // get the first hex digit
  var val1 = str.charCodeAt(0);

  // do some error checking
  if ( val1 >= 48 && val1 <= 57 )
      // have a valid digit 0-9
      val1 -= 48;
   else if ( val1 >= 65 && val1 <= 70 )
      // have a valid digit A-F
      val1 -= 55;
   else if ( val1 >= 97 && val1 <= 102 )
      // have a valid digit A-F
      val1 -= 87;
   else
   {
      // not 0-9 or A-F, complain
      window.alert( str.charAt(1)+" is not a valid hex digit" );
      return -1;
   }

  // get the second hex digit
  var val2 = str.charCodeAt(1);

  // do some error checking
  if ( val2 >= 48 && val2 <= 57 )
      // have a valid digit 0-9
      val2 -= 48;
   else if ( val2 >= 65 && val2 <= 70 )
      // have a valid digit A-F
      val2 -= 55;
   else if ( val2 >= 97 && val2 <= 102 )
      // have a valid digit A-F
      val2 -= 87;
   else
   {
      // not 0-9 or A-F, complain
      window.alert( str.charAt(2)+" is not a valid hex digit" );
      return -1;
   }

   // all is ok, return the value
   return val1*16 + val2;
}

// S-Box substitution table
var S_enc = new Array(
 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);

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

// convert two-dimensional indicies to one-dim array indices
var I00 = 0;
var I01 = 1;
var I02 = 2;
var I03 = 3;
var I10 = 4;
var I11 = 5;
var I12 = 6;
var I13 = 7;
var I20 = 8;
var I21 = 9;
var I22 = 10;
var I23 = 11;
var I30 = 12;
var I31 = 13;
var I32 = 14;
var I33 = 15;
// conversion function for non-constant subscripts
// assume subscript range 0..3
function I(x,y)
{ return (x*4) + y; }

// remove spaces from input
function remove_spaces( instr )
{
   var i;
   var outstr="";

   for( i=0; i<instr.length; i++ )
      if ( instr.charAt(i) != " " )
         // not a space, include it
         outstr += instr.charAt(i);

   return outstr;
}

// get the message to encrypt/decrypt or the key
// return as a byte array
// modified by E.K.
//	fixed minByteLenght to 16 (hardcoded)
//	removed ascii option for encryption key
function get_value(str)
{
   var dbyte = new Array(16);
   var i;
   var val;	// one hex digit

   // have hex data - remove any spaces they used, then convert
   str = remove_spaces(str);

   // check length of data
   if ( str.length < 16*2 || str.length > 32 )
   {
      window.alert("Message/key length wrong: Is " + str.length +
		" hex digits, but must be 128 bits (32 hex digits)");
      dbyte[0] = -1;
      return dbyte;
   }

   for( i=0; i<16; i++ )
   {
      // isolate and convert this substring
      dbyte[i] = cvt_byte( str.substr(i*2,2) );
      if( dbyte[i] < 0 )
      {
         // have an error
         dbyte[0] = -1;
         return dbyte;
      }
   } // for i

   // return successful conversion
   return dbyte;
} // get_value

//do the AES GF(2**8) multiplication
// do this by the shift-and-"add" approach
function aes_mul( a, b )
{
   var res = 0;

   while( a > 0 )
   {
      if ( a&1 )
         res = res ^ b;		// "add" to the result
      a >>>= 1;			// shift a to get next higher-order bit
      b <<= 1;			// shift multiplier also
   }

   // now reduce it modulo x**8 + x**4 + x**3 + x + 1
   var hbit = 0x10000;		// bit to test if we need to take action
   var modulus = 0x11b00;	// modulus - XOR by this to change value
   while( hbit >= 0x100 )
   {
      if ( res & hbit )		// if the high-order bit is set
         res ^= modulus;	// XOR with the modulus

      // prepare for the next loop
      hbit >>= 1;
      modulus >>= 1;
   }

   return res;
}

// apply the S-box substitution to the key expansion
function SubWord( word_ary )
{
   var i;

   for( i=0; i<16; i++ )
      word_ary[i] = S_enc[ word_ary[i] ];

   return word_ary;
}

// rotate the bytes in a word
function RotWord( word_ary )
{
   return new Array( word_ary[1], word_ary[2], word_ary[3], word_ary[0] );
}

// calculate the first item Rcon[i] = { x^(i-1), 0, 0, 0 }
// note we only return the first item
function Rcon( exp )
{
   var val = 2;
   var result = 1;

   // remember to calculate x^(exp-1)
   exp--;

   // process the exponent using normal shift and multiply
   while ( exp > 0 )
   {
      if ( exp & 1 )
         result = aes_mul( result, val );

      // square the value
      val = aes_mul( val, val );

      // move to the next bit
      exp >>= 1;
   }

   return result;
}

// round key generation
// return a byte array with the expanded key information
function key_expand( key )
{
   var temp = new Array(4);
   var i, j;
   var w = new Array( 4*11 );

   // copy initial key stuff
   for( i=0; i<16; i++ )
   {
      w[i] = key[i];
   }

   // generate rest of key schedule using 32-bit words
   i = 4;
   while ( i < 44 )		// blocksize * ( rounds + 1 )
   {
      // copy word W[i-1] to temp
      for( j=0; j<4; j++ )
         temp[j] = w[(i-1)*4+j];

      if ( i % 4 == 0)
      {
         // temp = SubWord(RotWord(temp)) ^ Rcon[i/4];
         temp = RotWord( temp );
         temp = SubWord( temp );
         temp[0] ^= Rcon( i>>>2 );
      }

      // word = word ^ temp
      for( j=0; j<4; j++ )
         w[i*4+j] = w[(i-4)*4+j] ^ temp[j];

      i++;
   }

   return w;
}

// do S-Box substitution
function SubBytes(state, Sbox)
{
   var i;

   for( i=0; i<16; i++ )
      state[i] = Sbox[ state[i] ];

   return state;
}

// shift each row as appropriate
function ShiftRows(state)
{
   var t0, t1, t2, t3;

   // top row (row 0) isn't shifted

   // next row (row 1) rotated left 1 place
   t0 = state[I10];
   t1 = state[I11];
   t2 = state[I12];
   t3 = state[I13];
   state[I10] = t1;
   state[I11] = t2;
   state[I12] = t3;
   state[I13] = t0;

   // next row (row 2) rotated left 2 places
   t0 = state[I20];
   t1 = state[I21];
   t2 = state[I22];
   t3 = state[I23];
   state[I20] = t2;
   state[I21] = t3;
   state[I22] = t0;
   state[I23] = t1;

   // bottom row (row 3) rotated left 3 places
   t0 = state[I30];
   t1 = state[I31];
   t2 = state[I32];
   t3 = state[I33];
   state[I30] = t3;
   state[I31] = t0;
   state[I32] = t1;
   state[I33] = t2;

   return state;
}

// inverset shift each row as appropriate
function InvShiftRows(state)
{
   var t0, t1, t2, t3;

   // top row (row 0) isn't shifted

   // next row (row 1) rotated left 1 place
   t0 = state[I10];
   t1 = state[I11];
   t2 = state[I12];
   t3 = state[I13];
   state[I10] = t3;
   state[I11] = t0;
   state[I12] = t1;
   state[I13] = t2;

   // next row (row 2) rotated left 2 places
   t0 = state[I20];
   t1 = state[I21];
   t2 = state[I22];
   t3 = state[I23];
   state[I20] = t2;
   state[I21] = t3;
   state[I22] = t0;
   state[I23] = t1;

   // bottom row (row 3) rotated left 3 places
   t0 = state[I30];
   t1 = state[I31];
   t2 = state[I32];
   t3 = state[I33];
   state[I30] = t1;
   state[I31] = t2;
   state[I32] = t3;
   state[I33] = t0;

   return state;
}

// process column info
function MixColumns(state)
{
   var col;
   var c0, c1, c2, c3;

   for( col=0; col<4; col++ )
   {
      c0 = state[I(0,col)];
      c1 = state[I(1,col)];
      c2 = state[I(2,col)];
      c3 = state[I(3,col)];

      // do mixing, and put back into array
      state[I(0,col)] = aes_mul(2,c0) ^ aes_mul(3,c1) ^ c2 ^ c3;
      state[I(1,col)] = c0 ^ aes_mul(2,c1) ^ aes_mul(3,c2) ^ c3;
      state[I(2,col)] = c0 ^ c1 ^ aes_mul(2,c2) ^ aes_mul(3,c3);
      state[I(3,col)] = aes_mul(3,c0) ^ c1 ^ c2 ^ aes_mul(2,c3);
   }

   return state;
}

// inverse process column info
function InvMixColumns(state)
{
   var col;
   var c0, c1, c2, c3;

   for( col=0; col<4; col++ )
   {
      c0 = state[I(0,col)];
      c1 = state[I(1,col)];
      c2 = state[I(2,col)];
      c3 = state[I(3,col)];

      // do inverse mixing, and put back into array
      state[I(0,col)] = aes_mul(0x0e,c0) ^ aes_mul(0x0b,c1)
			^ aes_mul(0x0d,c2) ^ aes_mul(0x09,c3);
      state[I(1,col)] = aes_mul(0x09,c0) ^ aes_mul(0x0e,c1)
			^ aes_mul(0x0b,c2) ^ aes_mul(0x0d,c3);
      state[I(2,col)] = aes_mul(0x0d,c0) ^ aes_mul(0x09,c1)
			^ aes_mul(0x0e,c2) ^ aes_mul(0x0b,c3);
      state[I(3,col)] = aes_mul(0x0b,c0) ^ aes_mul(0x0d,c1)
			^ aes_mul(0x09,c2) ^ aes_mul(0x0e,c3);
   }

   return state;
}

// insert subkey information
function AddRoundKey( state, w, base )
{
   var col;

   for( col=0; col<4; col++ )
   {
      state[I(0,col)] ^= w[base+col*4];
      state[I(1,col)] ^= w[base+col*4+1];
      state[I(2,col)] ^= w[base+col*4+2];
      state[I(3,col)] ^= w[base+col*4+3];
   }

   return state;
}

// return a transposed array
function transpose( msg )
{
   var row, col;
   var state = new Array( 16 );

   for( row=0; row<4; row++ )
      for( col=0; col<4; col++ )
         state[I(row,col)] = msg[I(col,row)];

   return state;
}

// do encrytion
// msg: 16-byte array with the message
// w:   array with expanded 44-word key
// returns a 16-element byte array
function aes_encrypt( msg, w )
{
   var state = new Array( 16 );			// working state
   var round;

   // initial state = message in columns (transposed from what we input)
   state = transpose( msg );

   // insert the round key
   state = AddRoundKey(state, w, 0);

   for( round=1; round<10; round++ )
   {
      state = SubBytes(state, S_enc);
      state = ShiftRows(state);
      state = MixColumns(state);
      // note here the spec uses 32-bit words, we are using bytes, so an extra *4
      state = AddRoundKey(state, w, round*4*4);
   }

   SubBytes(state, S_enc);
   ShiftRows(state);
   AddRoundKey(state, w, 10*4*4);

   // process output
   return transpose( state );
}

// do decryption
// msg: 16-byte array with the message
// w:   array with expanded 44-word key
// returns a 16-element byte array
function aes_decrypt( msg, w )
{
   var state = new Array( 16 );			// working state
   var round;

   // initial state = message
   state = transpose( msg );
   state = AddRoundKey(state, w, 10*4*4);

   for( round=9; round>=1; round-- )
   {
      state = InvShiftRows(state);
      state = SubBytes(state, S_dec);
      // display the round key - Transpose due to the way it is stored/used
      // note here the spec uses 32-bit words, we are using bytes, so an extra *4
      state = AddRoundKey(state, w, round*4*4);
      state = InvMixColumns(state);
   }

   InvShiftRows(state);
   SubBytes(state, S_dec);
   AddRoundKey(state, w, 0);

   // process output
   return transpose( state );
}

// xor the elements of two arrays together
function xor_array( a1, a2 )
{
   var i;
   var res = Array();

   for( i=0; i<a1.length; i++ )
      res[i] = a1[i] ^ a2[i];

   return res;
}

// "add to" the last byte of an array
function add_array( ary, amount )
{
   var i;
   var carry = amount;
   var temp;

   var res = Array();

   for( i=ary.length-1; i>=0; i-- )
   {
      temp = carry + ary[i];
      res[i] = temp & 0x0ff;
      carry = temp >>> 8;
   }

   return res;
}

// Rewritten by E.K.
//	only support output feedback
//	allows unlimited message length
function encrypt_aes_chain(hexkey, hexiv, data) {
   var output = '';
   var AES_output = new Array();
   var i = 0;
   var msglength = Math.ceil(data.length / 16);

   // get the initial vector
   var iv = get_value( hexiv );
   // problems??

   // get the key from the user
   var key = get_value( hexkey );
   // problems??

   // expand the key
   w = key_expand( key );

   state = iv;
   for( i=0; i<msglength; i++ ) {
      document.dst.messages.value = "Encoding chunk " + i + " of " + msglength;
      var chunk = data.substring(i*16, (i+1)*16);
      var msg = Array();
      for (var j=0; j < chunk.length; j++) {
         msg[j] = chunk.charCodeAt(j);
      }
      state = aes_encrypt( state, w );

      AES_output = xor_array( msg, state );
      for (var j=0; j < AES_output.length; j++) {
         output += String.fromCharCode(AES_output[j]);
      }
   }
   return output;
}

// Rewritten by E.K.
function decrypt_aes_chain(hexkey, hexiv, data) {
   return encrypt_aes_chain(hexkey, hexiv, data);
}