From 8daa83a594a2e98f39d764422bfbdbc62c9efd44 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 19:20:00 +0200 Subject: Adding upstream version 2:4.20.0+dfsg. Signed-off-by: Daniel Baumann --- .../lib/hcrypto/libtommath/bn_mp_prime_fermat.c | 47 ++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 third_party/heimdal/lib/hcrypto/libtommath/bn_mp_prime_fermat.c (limited to 'third_party/heimdal/lib/hcrypto/libtommath/bn_mp_prime_fermat.c') diff --git a/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_prime_fermat.c b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_prime_fermat.c new file mode 100644 index 0000000..af3e884 --- /dev/null +++ b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_prime_fermat.c @@ -0,0 +1,47 @@ +#include "tommath_private.h" +#ifdef BN_MP_PRIME_FERMAT_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ + +/* performs one Fermat test. + * + * If "a" were prime then b**a == b (mod a) since the order of + * the multiplicative sub-group would be phi(a) = a-1. That means + * it would be the same as b**(a mod (a-1)) == b**1 == b (mod a). + * + * Sets result to 1 if the congruence holds, or zero otherwise. + */ +mp_err mp_prime_fermat(const mp_int *a, const mp_int *b, mp_bool *result) +{ + mp_int t; + mp_err err; + + /* default to composite */ + *result = MP_NO; + + /* ensure b > 1 */ + if (mp_cmp_d(b, 1uL) != MP_GT) { + return MP_VAL; + } + + /* init t */ + if ((err = mp_init(&t)) != MP_OKAY) { + return err; + } + + /* compute t = b**a mod a */ + if ((err = mp_exptmod(b, a, a, &t)) != MP_OKAY) { + goto LBL_T; + } + + /* is it equal to b? */ + if (mp_cmp(&t, b) == MP_EQ) { + *result = MP_YES; + } + + err = MP_OKAY; +LBL_T: + mp_clear(&t); + return err; +} +#endif -- cgit v1.2.3