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36 lines
992 B
C
36 lines
992 B
C
#include "verify.h"
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/*-------------------------------------------------
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This file has been adapted from the implementation
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(available at https://github.com/pq-crystals/kyber) of
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"CRYSTALS – Kyber: a CCA-secure module-lattice-based KEM"
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by : Joppe Bos, Leo Ducas, Eike Kiltz, Tancrede Lepoint,
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Vadim Lyubashevsky, John M. Schanck, Peter Schwabe & Damien stehle
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----------------------------------------------------*/
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/* returns 0 for equal strings, 1 for non-equal strings */
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uint8_t PQCLEAN_LIGHTSABER_CLEAN_verify(const uint8_t *a, const uint8_t *b, size_t len) {
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uint64_t r;
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size_t i;
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r = 0;
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for (i = 0; i < len; i++) {
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r |= a[i] ^ b[i];
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}
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r = (~r + 1); // Two's complement
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r >>= 63;
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return (uint8_t) r;
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}
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/* b = 1 means mov, b = 0 means don't mov*/
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void PQCLEAN_LIGHTSABER_CLEAN_cmov(uint8_t *r, const uint8_t *x, size_t len, uint8_t b) {
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size_t i;
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b = -b;
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for (i = 0; i < len; i++) {
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r[i] ^= b & (x[i] ^ r[i]);
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}
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}
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