1. A mobile computer comprising: a random access memory (RAM); a network interface controller; and a processor coupled to the RAM, the processor comprising: a plurality of cores; a level 1 instruction cache to cache instructions; a level 1 data cache; a bus interface unit; a plurality of 128-bit registers; a decode unit to decode the instructions from the level 1 instruction cache including an Advanced Encryption Standard (AES) decryption instruction of an instruction set of the processor, the AES decryption instruction to use a first 128-bit source and destination register of the plurality of 128-bit registers and a second 128-bit source register of the plurality of 128-bit registers; and an execution unit coupled to the decode unit, the AES decryption instruction to cause the execution unit to receive data from the first 128-bit source and destination register and the second 128-bit source register, perform operations for an AES single decryption round including an inverse byte substitution, an inverse shift rows, and an exclusive OR, but omitting an inverse mix columns, and store a result in the first 128-bit source and destination register.