According to one embodiment, a processor includes an instruction decoder to receive a first instruction to process a SHA1 hash algorithm, the first instruction having a first operand, a second operand, and a third operand, the first operand specifying a first storage location storing four SHA states, the second operand specifying a second storage location storing a plurality of SHA1 message inputs in combination with a fifth SHA1 state. The processor further includes an execution unit coupled to the instruction decoder, in response to the first instruction, to perform at least four rounds of the SHA1 round operations on the SHA1 states and the message inputs obtained from the first and second operands, using a combinational logic function specified in the third operand.