Define auth_cfg rules for signature schemes

src/libstrongswan/credentials/auth_cfg.h

@@ -99,6 +99,8 @@ enum auth_rule_t {
 	AUTH_RULE_RSA_STRENGTH,
 	/** required ECDSA public key strength, u_int in bits */
 	AUTH_RULE_ECDSA_STRENGTH,
+	/** required signature scheme, signature_scheme_t */
+	AUTH_RULE_SIGNATURE_SCHEME,
 	/** certificatePolicy constraint, numerical OID as char* */
 	AUTH_RULE_CERT_POLICY,