+/*************************************************
+* Exim - an Internet mail transport agent *
+*************************************************/
+
+/* Copyright (c) Jeremy Harris 1995 - 2018 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Signing and hashing routine selection for PDKIM */
+
+#include "../exim.h"
+#include "../sha_ver.h"
+
+
+#ifdef USE_GNUTLS
+# include <gnutls/gnutls.h>
+
+# if GNUTLS_VERSION_NUMBER >= 0x030000
+# define SIGN_GNUTLS
+# if GNUTLS_VERSION_NUMBER >= 0x030600
+# define SIGN_HAVE_ED25519
+# endif
+# else
+# define SIGN_GCRYPT
+# endif
+
+#else
+# define SIGN_OPENSSL
+# if !defined(LIBRESSL_VERSION_NUMBER) && OPENSSL_VERSION_NUMBER >= 0x10101000L
+# define SIGN_HAVE_ED25519
+# endif
+
+#endif
+