memcpy(old_signing_key, signing_key, HASHSIZE);
gcry_randomize(signing_key, HASHSIZE, GCRY_STRONG_RANDOM);
signing_key_validity_limit = now + config->cookie_key_lifetime;
memcpy(old_signing_key, signing_key, HASHSIZE);
gcry_randomize(signing_key, HASHSIZE, GCRY_STRONG_RANDOM);
signing_key_validity_limit = now + config->cookie_key_lifetime;