int gpg_sign_detached_ed25519(const char *key_id, const uint8_t *message, size_t message_len, uint8_t signature_out[64])
Sign message with GPG and extract raw Ed25519 signature.
int gpg_sign_with_key(const char *key_id, const uint8_t *message, size_t message_len, uint8_t *signature_out, size_t *signature_len_out)
Sign a message using GPG key and return OpenPGP signature.