mbedtls_mpi_core_random() function

Generate a random number uniformly in a range. This function generates a random number between \p min inclusive and \p N exclusive. The procedure complies with RFC 6979 §3.3 (deterministic ECDSA) when the RNG is a suitably parametrized instance of HMAC_DRBG and \p min is \c 1.

Syntax

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Summary

Declaration

Definition

from bignum_core.h:602

int mbedtls_mpi_core_random(mbedtls_mpi_uint *X, mbedtls_mpi_uint min, const mbedtls_mpi_uint *N, size_t limbs, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng);

Implemented in bignum_core.c:637

Arguments

Argument

Description

The destination MPI, with \p limbs limbs. It must not be aliased with \p N or otherwise overlap it.

min

The minimum value to return.

The upper bound of the range, exclusive, with \p limbs limbs. In other words, this is one plus the maximum value to return. \p N must be strictly larger than \p min.

limbs

The number of limbs of \p N and \p X. This must not be 0.

f_rng

The RNG function to use. This must not be \c NULL.

p_rng

The RNG parameter to be passed to \p f_rng.

Return value

\c 0 if successful. #MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if the implementation was unable to find a suitable value within a limited number of attempts. This has a negligible probability if \p N is significantly larger than \p min, which is the case for all usual cryptographic applications.