Quality of random numbers - The Libgcrypt Reference Manual

Libgcypt offers random numbers of different quality levels:

— Data type: enum gcry_random_level

The constants for the random quality levels are of this type.

GCRY_WEAK_RANDOM: This should not anymore be used. It has recently been changed to an alias of GCRY_STRONG_RANDOM. Use gcry_create_nonce instead.
GCRY_STRONG_RANDOM: Use this level for e.g. session keys and similar purposes.
GCRY_VERY_STRONG_RANDOM: Use this level for e.g. key material.