static int audit_proof_cb(SSL *s, void *arg)
	{
	const unsigned char *proof;
	size_t proof_len;
	size_t i;
	SSL_SESSION *sess = SSL_get_session(s);

	proof = SSL_SESSION_get_tlsext_authz_server_audit_proof(sess,
								&proof_len);
	if (proof != NULL)
		{
		BIO_printf(bio_c_out, "Audit proof: ");
		for (i = 0; i < proof_len; ++i)
			BIO_printf(bio_c_out, "%02X", proof[i]);
		BIO_printf(bio_c_out, "\n");
		}
	else
		{
		BIO_printf(bio_c_out, "No audit proof found.\n");
		}
	return 1;
	}