1. A method comprising: modifying a data operand having a plurality of dwords by: overwriting a second dword and a fourth dword by copying a first dword to the second dword and copying a third dword to the fourth dword; performing a byte substitution on all bytes of each of the plurality of dwords in the data operand in parallel; performing a rotate word on the first dword and a rotate word on the fourth dword in parallel; and performing an exclusive OR operation on the first dword and an immediate byte and an exclusive OR operation on the fourth dword and the immediate byte in parallel.