The next 2 functions are used to compare MPIs:
int
gcry_mpi_cmp (const gcry_mpi_t u, const gcry_mpi_t v)
¶Compare the multi-precision-integers number u and v,
returning 0 for equality, a positive value for u > v and a
negative for u < v. If both numbers are opaque values
(cf. gcry_mpi_set_opaque
), the comparison is done by checking the bit
sizes using memcmp. If only one number is an opaque value, the opaque
value is less than the other number.
int
gcry_mpi_cmp_ui (const gcry_mpi_t u, unsigned long v)
¶Compare the multi-precision-integers number u with the unsigned integer v, returning 0 for equality, a positive value for u > v and a negative for u < v.
int
gcry_mpi_is_neg (const gcry_mpi_t a)
¶Return 1 if a is less than zero; return 0 if zero or positive.