used to influence
   the prime number generation process.  */
gcry_error_t gcry_prime_generate (gcry_mpi_t *prime,
                                  unsigned int prime_bits,
                                  unsigned int factor_bits,
                                  gcry_mpi_t **factors,
                                  gcry_prime_check_func_t cb_func,
                                  void *cb_arg,
                                  gcry_random_level_t random_level,
                                  unsigned int flags);

/* Find a generator for PRIME where the factorization of (prime-1) is
   in the NULL terminated array FACTORS. Return the generator as a
   newly allocated MPI in R_G.  If START_G is not NULL, use this as
   the start for the search. */
gcry_error_t gcry_prime_group_generator (gcry_mpi_t *r_g,
                                         gcry_mpi_t prime,
                                         gcry_mpi_t *factors,
                                         gcry_mpi_t start_g);


/* Convenience function to release the FACTORS array. */
void gcry_prime_release_factors (gcry_mpi_t *factors);


/* Check whether the number X is prime.  */
gcry_error_t gcry_prime_check (gcry_mpi_t x, unsigned int flags);