An apparatus and method are described for executing hash functions on a processor. For example, one embodiment of a processor comprises: a register set including a first storage location and a second storage location in which state variables for a hash function are to be stored; an execution unit to execute the hash function and to initially designate the first storage location as storing a first set of state values used for computing rounds of the hash function, and to initially designate a second storage location as storing a second set of state values also used for computing the rounds of the hash function; and the execution unit to execute a plurality of rounds of the hash function using the first and second sets of state data, wherein executing includes swapping the designations of the first storage location and second storage location such that the first storage location is designated to store the first set of state values for a first set of rounds and the second set of state values for a second set of rounds, and wherein the second storage location is designated to store the second set of state values for the first set of rounds and the first set of state values for the second set of rounds.