Rijndael's encryption algorith for AES

aesalg.js

// do encrytion
function aes_encrypt(message,crypt_key)
{
   var w = new Array( 44 );			// subkey information
   var state = new Array( 16 );			// working state
   var round;

   msg=get_value(message,true);
   key=get_value(crypt_key,false);
   
   // expand the key
   w = key_expand( key );

   state = transpose( msg );

   state = AddRoundKey(state, w, 0);

   for( round=1; round<10; round++ )
   {
      state = SubBytes(state, S_enc);
      state = ShiftRows(state);
      state = MixColumns(state);
      state = AddRoundKey(state, w, round*4*4);
   }

   SubBytes(state, S_enc);
   //accumulate_array( "After SubBytes", state );
   ShiftRows(state);
   //accumulate_array( "After ShiftRows", state );
   AddRoundKey(state, w, 10*4*4);
   //accumulate_array( "Output", state );

   // process output
   AES_output = transpose( state );
   return format_AES_output();
} 
 
// do decryption
function aes_decrypt(message,crypt_key)
{
   var w = new Array( 44 );			// subkey information
   var state = new Array( 16 );			// working state
   var round;

   msg=get_value(message,false);
   key=get_value(crypt_key,false);
   // expand the key
   w = key_expand( key );

   // initial state = message
   state = transpose( msg );

   // display the round key - Transpose due to the way it is stored/used
   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
   AES_output = transpose( state );
   return format_AES_output(false);
} 
 
 
// 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; }


//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) != 0 )
         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) != 0 )		// 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] );
}

function Rcon( exp )
{
   var val = 2;
   var result = 1;

   exp--;

   while ( exp > 0 )
   {
      if ( (exp & 1) != 0 )
         result = aes_mul( result, val );

      val = aes_mul( val, val );

      exp >>= 1;
   }

   return result;
}


function key_expand( key )
{
   var temp = new Array(4);
   var i, j;
   var w = new Array( 4*11 );

   for( i=0; i<16; i++ )
   {
      w[i] = key[i];
   }
   i = 4;
   while ( i < 44 )
   {
      for( j=0; j<4; j++ )
         temp[j] = w[(i-1)*4+j];

      if ( i % 4 == 0)
      {
         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;
}


// 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;
}

// 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;
}


// 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;
}

function get_value(str, isASCII )
{
   var dbyte = new Array(16);
   var i;
   var val;	// one hex digit

   if ( isASCII )
   {

      // have ASCII data
      // 16 characters?
      if ( str.length >= 16 )
      {
         // 16 or more characters
         for( i=0; i<16; i++ )
         {
            dbyte[i] = str.charCodeAt(i);
         }
      }
      else
      {
         // less than 16 characters - fill with NULLs
         for( i=0; i<str.length; i++ )
         {
            dbyte[i] = str.charCodeAt(i);
         }
         for( i=str.length; i<16; i++ )
         {
            dbyte[i] = 0;
         }
      }
         
   }
   else
   {
      // have hex data - remove any spaces they used, then convert
      str = remove_spaces(str);

      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
   } // if isASCII

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

// 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;
}
// 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;
}

// 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;
}

// do encrytion
function aes_encrypt(message,crypt_key)
{
   var w = new Array( 44 );			// subkey information
   var state = new Array( 16 );			// working state
   var round;

   msg=get_value(message,true);
   key=get_value(crypt_key,false);
   
   // expand the key
   w = key_expand( key );

   state = transpose( msg );

   state = AddRoundKey(state, w, 0);

   for( round=1; round<10; round++ )
   {
      state = SubBytes(state, S_enc);
      state = ShiftRows(state);
      state = MixColumns(state);
      state = AddRoundKey(state, w, round*4*4);
   }

   SubBytes(state, S_enc);
   //accumulate_array( "After SubBytes", state );
   ShiftRows(state);
   //accumulate_array( "After ShiftRows", state );
   AddRoundKey(state, w, 10*4*4);
   //accumulate_array( "Output", state );

   // process output
   AES_output = transpose( state );
   return format_AES_output();
}

// 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);
}

function format_AES_output(in_hex=true)
{
   var i;
   var bits;
   var str="";

   // what type of data do we have to work with?
   if (!in_hex)
   {
      // convert each set of bits back to ASCII
      for( i=0; i<16; i++ )
         str += String.fromCharCode( AES_output[i] );
   }
   else 
   {
      // output hexdecimal data (insert spaces)
      str = cvt_hex8( AES_output[0] );
      for( i=1; i<16; i++ )
      {
         str += " " + cvt_hex8( AES_output[i] );
      }
   }
   return str;
}


// final AES state
var AES_output = new Array(16);

// do decryption
function aes_decrypt(message,crypt_key)
{
   var w = new Array( 44 );			// subkey information
   var state = new Array( 16 );			// working state
   var round;

   msg=get_value(message,false);
   key=get_value(crypt_key,false);
   // expand the key
   w = key_expand( key );

   // initial state = message
   state = transpose( msg );

   // display the round key - Transpose due to the way it is stored/used
   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
   AES_output = transpose( state );
   return format_AES_output(false);
}