Common use of Key Schedule Clause in Contracts

Key Schedule. The round key is not stored in a bitsliced fashion and the key schedule is computed on the fly. Note that round key precomputation is also a valid implementation option, assuming that the key does not need to be renewed often. Since, key refreshing can act as a side-channel countermeasure, 6 ▇▇▇▇▇://▇▇▇.▇▇▇▇▇▇▇.▇▇▇/security-tools/hardware/pinata (Accessed 24 June 2016). we chose to retain the on-the-fly key updates. Updating the round key requires a push through the Sbox for four bits each round. To that purpose, we use Cortex-M4’s UBFX instruction for extracting a contiguous series of bits from a word in an efficient manner. In addition, we used ARM’s barrel shifter function, which allows the second operand to be shifted with no additional cost before an instruction is performed.

Key Schedule. The round key is not stored in a bitsliced fashion and the key schedule is computed on the flyfly. Note that round key precomputation is also a valid implementation option, assuming that the key does not need to be renewed often. Since, key refreshing can act as a side-channel countermeasure, 6 ▇▇▇▇▇://▇▇▇.▇▇▇▇▇▇▇.▇▇▇/security-tools/hardware/pinata (Accessed 24 June 2016). we chose to retain the on-the-fly the-fly key updates. Updating the round key requires a push through the Sbox for four bits each round. To that purpose, we use Cortex-M4’s UBFX instruction for extracting a contiguous series of bits from a word in an efficient efficient manner. In addition, we used ARM’s barrel shifter function, which allows the second operand to be shifted with no additional cost before an instruction is performed.