An apparatus and method for performing cryptographic operations within microprocessor. The apparatus includes an instruction register having a cryptographic instruction disposed therein, a keygen unit, and an execution unit. The cryptographic instruction is received by a microprocessor as part of an instruction flow executing on the microprocessor. The cryptographic instruction prescribes one of the cryptographic operations, and also prescribes that a user-generated key schedule be employed when executing the one of the cryptographic operations. The keygen unit is operatively coupled to the instruction register. The keygen unit directs the microprocessor to load the user-generated key schedule. The execution unit is operatively coupled to the keygen unit. The execution unit employs the user-generated key schedule to execute the one of the cryptographic operations. The execution unit includes a cryptography unit.