code: function(state,isInv)
  		{
  			var column = [];
  			/* iterate over the 4 columns */
  			for (var i = 0; i < 4; i++)
  			{
  				/* construct one column by iterating over the 4 rows */
  				for (var j = 0; j < 4; j++)
  					column[j] = state[(j*4)+i];
  				/* apply the mixColumn on one column */
  				column = this.mixColumn(column,isInv);
  				/* put the values back into the state */
  				for (var k = 0; k < 4; k++)
  					state[(k*4)+i] = column[k];
  			}
  			return state;
  		}
docs: galois multipication of the 4x4 matrix