Validating Word-oriented Processors for Bit and Multi-Word Operations

Abstract. We examine secure computing paradigms to identify any new architectural challenges for future general-purpose processors. Some essential security functions can be provided by different classes of cryptography algorithms. We identify two categories of operations in these algorithms that are not common in previous general-purpose workloads: bit operations within a word and multi-word operations. Both challenge the basic word orientation of processors. We show how very complex bit-level operations, namely arbitrary bit permutations within a word, can be achieved in O(1) cycles, rather than O(n) cycles as in existing RISC processors. We describe two solutions: one using only microarchitecture changes, and another with Instruction Set Architecture (ISA) support. We generalize our solutions to define datarich execution with MOMR (Multi-word Operands Multi-word Result) functional units. This can address both challenges, leveraging available resources in typical processors with minimal additional cost. Thus we validate the basic word-orientation of processor architectures, since they can also provide superior performance for both bit and multi-word operations needed by cryptographic processing. 1