Patent ID: 11943332
Assignee: TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 6:
7. A method of performing a substitution box (SBox) computational step in cryptographic circuitry, the method comprising:
generating a 4-bit first output signal (Y) from an 8-bit input signal (U);
generating, in parallel with generating the 4-bit first output signal (Y), generating a 32-bit second output signal (L) from the input signal (U), wherein the 32-bit second output signal (L) consists of four 8-bit sub-results;
producing four preliminary 8-bit results (K) by scalar multiplying each of the four 8-bit sub-results by a respective one bit of the 4-bit first output signal (Y); and
producing an 8-bit output signal (R) by summing the four preliminary 8-bit results (K),
wherein:
generating the 4-bit first output signal (Y) from the input signal (U) comprises performing a calculation that comprises a first linear matrix operation, a Galois Field (GF) multiplication, and a GF inversion; and
generating the second output signal (L) from the input signal (U) comprises performing a calculation that comprises a second linear matrix operation.