The RISC-V Cryptography Extensions Task Group has opened a public review period on a raft of instruction set extensions, ahead of their planned adoption as official standards – including instructions for AES encryption and decryption and the SM3 hash and SM4 block cipher.

“This specification has been developed by the RISC-V Cryptography Extensions Task Group under the governance of the Unprivileged and the Security Committees,” says Richard Newell, chair of the RISC-V Cryptography Extensions Task Group and an associate technical fellow at Microchip.

“During the public review period, corrections, comments, and suggestions, will be gathered for review by the Cryptography task group. Any minor corrections and/or uncontroversial changes will be incorporated into the specification. Any remaining issues or proposed changes will be addressed in the public review summary report.

“If there are no issues that require incompatible changes to the public review specification,” Newell notes, “the unprivileged ISA committee will recommend the updated specifications be approved and ratified by the RISC-V Technical Steering Committee and the RISC-V Board of Directors.”

The extensions in question cover a range of cryptographic operations, including the Zknd and Zkne instructions for AES decryption and encryption respectively, the Zknh hash function instructions, Zksed and Zsksh for the ShangMi SM4 block cipher and SM3 hash function respectively, Zkr for entropy source operations, Zbkb for bit manipulation (bitmanip) instructions focused on cryptography, Zbkc for carry-less multiplication, and Zbkx for crossbar permutation.

The latest release of the extensions, gathered together as “Scalar Cryptography,” is available on the RISC-V GitHub repository now. Those looking to comment can do so on the RISC-V ISA Dev mailing list or via Issues and Pull Requests on the GitHub repository.

The review period runs through until the end of Sunday, 17th of October 2021.