dst_key_sigsize
dst_key_sigsize(const dst_key_t *key, unsigned int *n);
RUNTIME_CHECK(dst_key_sigsize(key, &maxbits) == ISC_R_SUCCESS);
result = dst_key_sigsize(key->key, &x);
ret = dst_key_sigsize(key, &siglen);
ret = dst_key_sigsize(key, &siglen);
ret = dst_key_sigsize(key->key, &sigsize);
ret = dst_key_sigsize(key, &siglen);