NAME
BN_nist_mod_192,
BN_nist_mod_224,
BN_nist_mod_256,
BN_nist_mod_384,
BN_nist_mod_521 —
reduction modulo NIST-recommended
primes
SYNOPSIS
#include
<openssl/bn.h>
int
BN_nist_mod_192(BIGNUM *r,
const BIGNUM *a, const BIGNUM
*m, BN_CTX *ctx);
int
BN_nist_mod_224(BIGNUM *r,
const BIGNUM *a, const BIGNUM
*m, BN_CTX *ctx);
int
BN_nist_mod_256(BIGNUM *r,
const BIGNUM *a, const BIGNUM
*m, BN_CTX *ctx);
int
BN_nist_mod_384(BIGNUM *r,
const BIGNUM *a, const BIGNUM
*m, BN_CTX *ctx);
int
BN_nist_mod_521(BIGNUM *r,
const BIGNUM *a, const BIGNUM
*m, BN_CTX *ctx);
DESCRIPTION
These functions are optimized versions of BN_nnmod(3) using precomputed tables. They ignore their m argument and use the following moduli instead:
They reduce a modulo the respective prime number and place the non-negative remainder in r.
These functions are designed to save time when performing multiplications in prime fields of these specific orders. Consequently, if a is negative or larger than the square of the modulus being used, they call BN_nnmod(3) instead of attempting any optimization.
RETURN VALUES
These functions return 1 on success or 0 on error.
SEE ALSO
BN_get0_nist_prime_521(3), BN_nnmod(3), EC_GFp_nist_method(3)
STANDARDS
Digital Signature Standard (DSS), National Institute of Standards and Technology, FIPS PUB 186-4, https://doi.org/10.6028/NIST.FIPS.186-4, Information Technology Laboratory, Gaithersburg, Maryland, July 2013, Appendix D.1.2 Curves over Prime Fields.