METHOD FOR PROCESSING DATA INVOLVING MODULAR EXPONENTIATION AND RELATED DEVICE

摘要

The invention concerns a data processing method, whereby an element is subjected to a first operation with a given operand. Said method includes a step of updating by a second operation a first variable (B; a0; S'p, S'q) or a second variable (A; a1; Sp, Sq),depending on whether a corresponding bit of the operand = 0 or 1; and a step of testing a relationship between a first value (B; a0; S') derived from the first variable and a second value (A; a1; S) derived from the second variable. The invention also concerns a related device.