Support GnuTLS as an alternative crypto backend

This turns the `-Dgcrypt` build time option into a more generic
`-Dcrypto` option, which enables user to choose which cryptographic
library to link with.  It currently supports libgcrypt (`libgcrypt`)
and GnuTLS (`gnutls`); for the latter, GnuTLS 3.8.2 is the minimum
required version.

Signed-off-by: Daiki Ueno <dueno@src.gnome.org>

egg/egg-dh-gnutls.c

@@ -0,0 +1,261 @@
+/*
+ * libsecret
+ *
+ * Copyright (C) 2023 Daiki Ueno
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and
+ * the GNU Lesser General Public License along with this program.  If
+ * not, see http://www.gnu.org/licenses/.
+ *
+ * Author: Daiki Ueno
+ */
+
+#include "config.h"
+
+#include "egg-dh.h"
+
+/* Enabling this is a complete security compromise */
+#define DEBUG_DH_SECRET 0
+
+#include <gnutls/gnutls.h>
+#include <gnutls/abstract.h>
+
+struct egg_dh_params {
+	gnutls_dh_params_t inner;
+	guint bits;
+};
+
+struct egg_dh_pubkey {
+	gnutls_pubkey_t inner;
+};
+
+struct egg_dh_privkey {
+	gnutls_privkey_t inner;
+};
+
+egg_dh_params *
+egg_dh_default_params (const gchar *name)
+{
+	const egg_dh_group *group;
+	egg_dh_params *params;
+
+	g_return_val_if_fail (name, NULL);
+
+	for (group = egg_dh_groups; group->name; ++group) {
+		if (g_str_equal (group->name, name)) {
+			gnutls_dh_params_t inner;
+			gnutls_datum_t prime, generator;
+			int ret;
+
+			ret = gnutls_dh_params_init (&inner);
+			if (ret < 0)
+				return NULL;
+
+			prime.data = (void *)group->prime;
+			prime.size = group->n_prime;
+			generator.data = (void *)group->base;
+			generator.size = group->n_base;
+
+			ret = gnutls_dh_params_import_raw (inner,
+							   &prime,
+							   &generator);
+			if (ret < 0) {
+				gnutls_dh_params_deinit (inner);
+				return NULL;
+			}
+
+			params = g_new (struct egg_dh_params, 1);
+			if (!params) {
+				gnutls_dh_params_deinit (inner);
+				return NULL;
+			}
+			params->inner = g_steal_pointer (&inner);
+			params->bits = group->bits;
+			return params;
+		}
+	}
+
+	return NULL;
+}
+
+gboolean
+egg_dh_gen_pair (egg_dh_params *params, guint bits,
+                 egg_dh_pubkey **pub, egg_dh_privkey **priv)
+{
+	gnutls_pubkey_t pub_inner = NULL;
+	gnutls_privkey_t priv_inner = NULL;
+	egg_dh_pubkey *pub_outer = NULL;
+	egg_dh_privkey *priv_outer = NULL;
+	gnutls_keygen_data_st data;
+	gboolean ok = FALSE;
+	int ret;
+
+	g_return_val_if_fail (params, FALSE);
+	g_return_val_if_fail (pub, FALSE);
+	g_return_val_if_fail (priv, FALSE);
+
+	if (bits == 0)
+		bits = params->bits;
+	else if (bits > params->bits)
+		g_return_val_if_reached (FALSE);
+
+	ret = gnutls_privkey_init (&priv_inner);
+	if (ret < 0)
+		goto out;
+
+	data.type = GNUTLS_KEYGEN_DH;
+	data.data = (void *)params->inner;
+
+	ret = gnutls_privkey_generate2 (priv_inner, GNUTLS_PK_DH, bits, 0,
+					&data, 1);
+	if (ret < 0)
+		goto out;
+
+	ret = gnutls_pubkey_init (&pub_inner);
+	if (ret < 0)
+		goto out;
+
+	ret = gnutls_pubkey_import_privkey (pub_inner, priv_inner, 0, 0);
+	if (ret < 0)
+		goto out;
+
+	pub_outer = g_new0 (struct egg_dh_pubkey, 1);
+	if (!pub_outer)
+		goto out;
+	pub_outer->inner = g_steal_pointer (&pub_inner);
+
+	priv_outer = g_new0 (struct egg_dh_privkey, 1);
+	if (!priv_outer)
+		goto out;
+	priv_outer->inner = g_steal_pointer (&priv_inner);
+
+	*pub = g_steal_pointer (&pub_outer);
+	*priv = g_steal_pointer (&priv_outer);
+
+	ok = TRUE;
+
+ out:
+	if (priv_inner)
+		gnutls_privkey_deinit (priv_inner);
+	if (pub_inner)
+		gnutls_pubkey_deinit (pub_inner);
+
+	egg_dh_privkey_free (priv_outer);
+	egg_dh_pubkey_free (pub_outer);
+
+	return ok;
+}
+
+GBytes *
+egg_dh_gen_secret (egg_dh_pubkey *peer, egg_dh_privkey *priv,
+                   egg_dh_params *params)
+{
+	int ret;
+	gnutls_datum_t k;
+#if DEBUG_DH_SECRET
+	gnutls_datum_t h;
+#endif
+
+	g_return_val_if_fail (peer, NULL);
+	g_return_val_if_fail (priv, NULL);
+	g_return_val_if_fail (params, NULL);
+
+	ret = gnutls_privkey_derive_secret (priv->inner, peer->inner,
+					    NULL, &k, 0);
+	if (ret < 0)
+		return NULL;
+
+#if DEBUG_DH_SECRET
+	ret = gnutls_hex_encode2 (&k, &h);
+	g_assert (ret >= 0);
+	g_printerr ("DH SECRET: %s\n", h.data);
+	gnutls_free (h.data);
+#endif
+
+	return g_bytes_new_with_free_func (k.data, k.size,
+					   (GDestroyNotify)gnutls_free,
+					   k.data);
+}
+
+void
+egg_dh_params_free (egg_dh_params *params)
+{
+	gnutls_dh_params_deinit (params->inner);
+	g_free (params);
+}
+
+void
+egg_dh_pubkey_free (egg_dh_pubkey *pubkey)
+{
+	if (!pubkey)
+		return;
+	if (pubkey->inner)
+		gnutls_pubkey_deinit (pubkey->inner);
+	g_free (pubkey);
+}
+
+void
+egg_dh_privkey_free (egg_dh_privkey *privkey)
+{
+	if (!privkey)
+		return;
+	if (privkey->inner)
+		gnutls_privkey_deinit (privkey->inner);
+	g_free (privkey);
+}
+
+GBytes *
+egg_dh_pubkey_export (const egg_dh_pubkey *pubkey)
+{
+	gnutls_datum_t data;
+	int ret;
+
+	ret = gnutls_pubkey_export_dh_raw (pubkey->inner, NULL, &data, 0);
+	if (ret < 0)
+		return NULL;
+
+	return g_bytes_new_with_free_func (data.data, data.size,
+					   (GDestroyNotify)gnutls_free,
+					   data.data);
+}
+
+egg_dh_pubkey *
+egg_dh_pubkey_new_from_bytes (const egg_dh_params *params, GBytes *bytes)
+{
+	egg_dh_pubkey *pub;
+	gnutls_pubkey_t inner;
+	gnutls_datum_t data;
+	int ret;
+
+	ret = gnutls_pubkey_init (&inner);
+	if (ret < 0)
+		return NULL;
+
+	data.data = (void *)g_bytes_get_data (bytes, NULL);
+	data.size = g_bytes_get_size (bytes);
+
+	ret = gnutls_pubkey_import_dh_raw (inner, params->inner, &data);
+	if (ret < 0) {
+		gnutls_pubkey_deinit (inner);
+		return NULL;
+	}
+
+	pub = g_new (struct egg_dh_pubkey, 1);
+	if (!pub) {
+		gnutls_pubkey_deinit (inner);
+		return NULL;
+	}
+
+	pub->inner = g_steal_pointer (&inner);
+	return pub;
+}

egg/egg-dh-libgcrypt.c

@@ -0,0 +1,278 @@
+/*
+ * gnome-keyring
+ *
+ * Copyright (C) 2009 Stefan Walter
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and
+ * the GNU Lesser General Public License along with this program.  If
+ * not, see http://www.gnu.org/licenses/.
+ *
+ * Author: Stef Walter <stefw@thewalter.net>
+ */
+
+#include "config.h"
+
+#include "egg-dh.h"
+
+#include <gcrypt.h>
+#include "egg-secure-memory.h"
+
+/* Enabling this is a complete security compromise */
+#define DEBUG_DH_SECRET 0
+
+EGG_SECURE_DECLARE (dh);
+
+struct egg_dh_params {
+	gcry_mpi_t prime;
+	gcry_mpi_t base;
+};
+
+struct egg_dh_pubkey {
+	gcry_mpi_t inner;
+};
+
+struct egg_dh_privkey {
+	gcry_mpi_t inner;
+};
+
+egg_dh_params *
+egg_dh_default_params (const gchar *name)
+{
+	const egg_dh_group *group;
+	gcry_error_t gcry;
+	gcry_mpi_t prime = NULL, base = NULL;
+	egg_dh_params *params = NULL;
+
+	g_return_val_if_fail (name, NULL);
+
+	for (group = egg_dh_groups; group->name; ++group)
+		if (g_str_equal (group->name, name))
+			break;
+	if (!group->name)
+		return NULL;
+
+	gcry = gcry_mpi_scan (&prime, GCRYMPI_FMT_USG,
+			      group->prime, group->n_prime, NULL);
+	g_return_val_if_fail (gcry == 0, NULL);
+	g_return_val_if_fail (gcry_mpi_get_nbits (prime) == group->bits, NULL);
+
+	gcry = gcry_mpi_scan (&base, GCRYMPI_FMT_USG,
+			      group->base, group->n_base, NULL);
+	g_return_val_if_fail (gcry == 0, NULL);
+
+	params = g_new (struct egg_dh_params, 1);
+	if (!params)
+		goto error;
+
+	params->prime = g_steal_pointer (&prime);
+	params->base = g_steal_pointer (&base);
+
+ error:
+	gcry_mpi_release (prime);
+	gcry_mpi_release (base);
+	return params;
+}
+
+gboolean
+egg_dh_gen_pair (egg_dh_params *params, guint bits,
+                 egg_dh_pubkey **pub, egg_dh_privkey **priv)
+{
+	guint pbits;
+	gcry_mpi_t pub_inner = NULL, priv_inner = NULL;
+
+	g_return_val_if_fail (params, FALSE);
+	g_return_val_if_fail (pub, FALSE);
+	g_return_val_if_fail (priv, FALSE);
+
+	*pub = NULL;
+	*priv = NULL;
+
+	pbits = gcry_mpi_get_nbits (params->prime);
+	g_return_val_if_fail (pbits > 1, FALSE);
+
+	if (bits == 0) {
+		bits = pbits;
+	} else if (bits > pbits) {
+		g_return_val_if_reached (FALSE);
+	}
+
+	/*
+	 * Generate a strong random number of bits, and not zero.
+	 * gcry_mpi_randomize bumps up to the next byte. Since we
+	 * need to have a value less than half of prime, we make sure
+	 * we bump down.
+	 */
+	priv_inner = gcry_mpi_snew (bits);
+	g_return_val_if_fail (priv_inner, FALSE);
+	while (gcry_mpi_cmp_ui (priv_inner, 0) == 0)
+		gcry_mpi_randomize (priv_inner, bits, GCRY_STRONG_RANDOM);
+
+	/* Secret key value must be less than half of p */
+	if (gcry_mpi_get_nbits (priv_inner) > bits)
+		gcry_mpi_clear_highbit (priv_inner, bits);
+	if (gcry_mpi_get_nbits (priv_inner) > pbits - 1)
+		gcry_mpi_clear_highbit (priv_inner, pbits - 1);
+	g_assert (gcry_mpi_cmp (params->prime, priv_inner) > 0);
+
+	pub_inner = gcry_mpi_new (gcry_mpi_get_nbits (priv_inner));
+	if (!pub_inner)
+		goto error;
+	gcry_mpi_powm (pub_inner, params->base, priv_inner, params->prime);
+
+	*priv = g_new0 (struct egg_dh_privkey, 1);
+	if (!*priv)
+		goto error;
+	(*priv)->inner = g_steal_pointer (&priv_inner);
+
+	*pub = g_new0 (struct egg_dh_pubkey, 1);
+	if (!*pub)
+		goto error;
+	(*pub)->inner = g_steal_pointer (&pub_inner);
+
+	return TRUE;
+ error:
+	egg_dh_privkey_free (*priv);
+	egg_dh_pubkey_free (*pub);
+
+	gcry_mpi_release (priv_inner);
+	gcry_mpi_release (pub_inner);
+
+	g_return_val_if_reached (FALSE);
+}
+
+GBytes *
+egg_dh_gen_secret (egg_dh_pubkey *peer, egg_dh_privkey *priv,
+                   egg_dh_params *params)
+{
+	gcry_error_t gcry;
+	guchar *value;
+	gsize n_prime;
+	gsize n_value;
+	gcry_mpi_t k;
+	gint bits;
+
+	g_return_val_if_fail (peer, NULL);
+	g_return_val_if_fail (priv, NULL);
+	g_return_val_if_fail (params, NULL);
+
+	bits = gcry_mpi_get_nbits (params->prime);
+	g_return_val_if_fail (bits >= 0, NULL);
+
+	k = gcry_mpi_snew (bits);
+	g_return_val_if_fail (k, NULL);
+	gcry_mpi_powm (k, peer->inner, priv->inner, params->prime);
+
+	/* Write out the secret */
+	gcry = gcry_mpi_print (GCRYMPI_FMT_USG, NULL, 0, &n_prime, params->prime);
+	g_return_val_if_fail (gcry == 0, NULL);
+
+	value = egg_secure_alloc (n_prime);
+	if (!value)
+		return NULL;
+
+	gcry = gcry_mpi_print (GCRYMPI_FMT_USG, value, n_prime, &n_value, k);
+	g_return_val_if_fail (gcry == 0, NULL);
+
+	/* Pad the secret with zero bytes to match length of prime in bytes. */
+	if (n_value < n_prime) {
+		memmove (value + (n_prime - n_value), value, n_value);
+		memset (value, 0, (n_prime - n_value));
+	}
+
+#if DEBUG_DH_SECRET
+	g_printerr ("DH SECRET: ");
+	gcry_mpi_dump (k);
+#endif
+	gcry_mpi_release (k);
+
+#if DEBUG_DH_SECRET
+	gcry_mpi_scan (&k, GCRYMPI_FMT_USG, value, n_prime, NULL);
+	g_printerr ("RAW SECRET: ");
+	gcry_mpi_dump (k);
+	gcry_mpi_release (k);
+#endif
+
+	return g_bytes_new_with_free_func (value, n_prime,
+					   (GDestroyNotify)egg_secure_free,
+					   value);
+}
+
+void
+egg_dh_params_free (egg_dh_params *params)
+{
+	if (!params)
+		return;
+	gcry_mpi_release (params->prime);
+	gcry_mpi_release (params->base);
+	g_free (params);
+}
+
+void
+egg_dh_pubkey_free (egg_dh_pubkey *pubkey)
+{
+	if (!pubkey)
+		return;
+	if (pubkey->inner)
+		gcry_mpi_release (pubkey->inner);
+	g_free (pubkey);
+}
+
+void
+egg_dh_privkey_free (egg_dh_privkey *privkey)
+{
+	if (!privkey)
+		return;
+	if (privkey->inner)
+		gcry_mpi_release (privkey->inner);
+	g_free (privkey);
+}
+
+GBytes *
+egg_dh_pubkey_export (const egg_dh_pubkey *pubkey)
+{
+	gcry_error_t gcry;
+	unsigned char *buffer;
+	size_t n_buffer;
+
+	gcry = gcry_mpi_aprint (GCRYMPI_FMT_USG, &buffer, &n_buffer,
+				pubkey->inner);
+	g_return_val_if_fail (gcry == 0, NULL);
+
+	return g_bytes_new_with_free_func (buffer, n_buffer,
+					   gcry_free, buffer);
+}
+
+egg_dh_pubkey *
+egg_dh_pubkey_new_from_bytes (const egg_dh_params *params,
+			      GBytes *bytes)
+{
+	gcry_error_t gcry;
+	gcry_mpi_t inner;
+	egg_dh_pubkey *pub;
+
+	gcry = gcry_mpi_scan (&inner, GCRYMPI_FMT_USG,
+			      g_bytes_get_data (bytes, NULL),
+			      g_bytes_get_size (bytes),
+			      NULL);
+	if (gcry != 0)
+		return NULL;
+
+	pub = g_new (struct egg_dh_pubkey, 1);
+	if (!pub) {
+		gcry_mpi_release (inner);
+		return NULL;
+	}
+
+	pub->inner = inner;
+	return pub;
+}

egg/egg-dh.c

@@ -13,10 +13,9 @@
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *  
- * You should have received a copy of the GNU Lesser General Public
+ * You should have received copies of the GNU General Public License and
- * License along with this program; if not, write to the Free Software
+ * the GNU Lesser General Public License along with this program.  If
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * not, see http://www.gnu.org/licenses/.
- * MA 02110-1301 USA
  *
  * Author: Stef Walter <stefw@thewalter.net>
  */
@@ -24,23 +23,6 @@
 #include "config.h"
 
 #include "egg-dh.h"
-#include "egg-secure-memory.h"
-
-#include <gcrypt.h>
-
-/* Enabling this is a complete security compromise */
-#define DEBUG_DH_SECRET 0
-
-EGG_SECURE_DECLARE (dh);
-
-typedef struct _DHGroup {
-	const gchar *name;
-	guint bits;
-	const guchar *prime;
-	gsize n_prime;
-	const guchar base[1];
-	gsize n_base;
-} DHGroup;
 
 static const guchar dh_group_768_prime[] = {
 	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2, 0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
@@ -173,7 +155,7 @@ static const guchar dh_group_8192_prime[] = {
 	0x60, 0xC9, 0x80, 0xDD, 0x98, 0xED, 0xD3, 0xDF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
 };
 
-static const DHGroup dh_groups[] = {
+const egg_dh_group egg_dh_groups[] = {
 	{
 		"ietf-ike-grp-modp-768", 768,
 		dh_group_768_prime, G_N_ELEMENTS (dh_group_768_prime),
@@ -214,24 +196,11 @@ static const DHGroup dh_groups[] = {
 	}
 };
 
-struct egg_dh_params {
-	gcry_mpi_t prime;
-	gcry_mpi_t base;
-};
-
-struct egg_dh_pubkey {
-	gcry_mpi_t inner;
-};
-
-struct egg_dh_privkey {
-	gcry_mpi_t inner;
-};
-
 gboolean
 egg_dh_default_params_raw (const gchar *name, gconstpointer *prime,
                            gsize *n_prime, gconstpointer *base, gsize *n_base)
 {
-	const DHGroup *group;
+	const egg_dh_group *group;
 
 	g_return_val_if_fail (name, FALSE);
 	g_return_val_if_fail (prime, FALSE);
@@ -239,7 +208,7 @@ egg_dh_default_params_raw (const gchar *name, gconstpointer *prime,
 	g_return_val_if_fail (base, FALSE);
 	g_return_val_if_fail (n_base, FALSE);
 
-	for (group = dh_groups; group->name; ++group) {
+	for (group = egg_dh_groups; group->name; ++group) {
 		if (g_str_equal (group->name, name)) {
 			*prime = group->prime;
 			*n_prime = group->n_prime;
@@ -251,232 +220,3 @@ egg_dh_default_params_raw (const gchar *name, gconstpointer *prime,
 
 	return FALSE;
 }
-
-egg_dh_params *
-egg_dh_default_params (const gchar *name)
-{
-	const DHGroup *group;
-	gcry_error_t gcry;
-	gcry_mpi_t prime = NULL, base = NULL;
-	egg_dh_params *params = NULL;
-
-	g_return_val_if_fail (name, NULL);
-
-	for (group = dh_groups; group->name; ++group)
-		if (g_str_equal (group->name, name))
-			break;
-	if (!group->name)
-		return NULL;
-
-	gcry = gcry_mpi_scan (&prime, GCRYMPI_FMT_USG,
-			      group->prime, group->n_prime, NULL);
-	g_return_val_if_fail (gcry == 0, NULL);
-	if (G_UNLIKELY (gcry_mpi_get_nbits (prime) != group->bits))
-		goto error;
-
-	gcry = gcry_mpi_scan (&base, GCRYMPI_FMT_USG,
-			      group->base, group->n_base, NULL);
-	if (gcry != 0)
-		goto error;
-
-	params = g_new (struct egg_dh_params, 1);
-	if (!params)
-		goto error;
-
-	params->prime = g_steal_pointer (&prime);
-	params->base = g_steal_pointer (&base);
-
- error:
-	gcry_mpi_release (prime);
-	gcry_mpi_release (base);
-	return params;
-}
-
-gboolean
-egg_dh_gen_pair (egg_dh_params *params, guint bits,
-                 egg_dh_pubkey **pub, egg_dh_privkey **priv)
-{
-	guint pbits;
-	gcry_mpi_t pub_inner = NULL, priv_inner = NULL;
-
-	g_return_val_if_fail (params, FALSE);
-	g_return_val_if_fail (pub, FALSE);
-	g_return_val_if_fail (priv, FALSE);
-
-	*pub = NULL;
-	*priv = NULL;
-
-	pbits = gcry_mpi_get_nbits (params->prime);
-	g_return_val_if_fail (pbits > 1, FALSE);
-
-	if (bits == 0) {
-		bits = pbits;
-	} else if (bits > pbits) {
-		g_return_val_if_reached (FALSE);
-	}
-
-	/*
-	 * Generate a strong random number of bits, and not zero.
-	 * gcry_mpi_randomize bumps up to the next byte. Since we
-	 * need to have a value less than half of prime, we make sure
-	 * we bump down.
-	 */
-	priv_inner = gcry_mpi_snew (bits);
-	g_return_val_if_fail (priv_inner, FALSE);
-	while (gcry_mpi_cmp_ui (priv_inner, 0) == 0)
-		gcry_mpi_randomize (priv_inner, bits, GCRY_STRONG_RANDOM);
-
-	/* Secret key value must be less than half of p */
-	if (gcry_mpi_get_nbits (priv_inner) > bits)
-		gcry_mpi_clear_highbit (priv_inner, bits);
-	if (gcry_mpi_get_nbits (priv_inner) > pbits - 1)
-		gcry_mpi_clear_highbit (priv_inner, pbits - 1);
-	g_assert (gcry_mpi_cmp (params->prime, priv_inner) > 0);
-
-	pub_inner = gcry_mpi_new (gcry_mpi_get_nbits (priv_inner));
-	if (!pub_inner)
-		goto error;
-	gcry_mpi_powm (pub_inner, params->base, priv_inner, params->prime);
-
-	*priv = g_new0 (struct egg_dh_privkey, 1);
-	if (!*priv)
-		goto error;
-	(*priv)->inner = g_steal_pointer (&priv_inner);
-
-	*pub = g_new0 (struct egg_dh_pubkey, 1);
-	if (!*pub)
-		goto error;
-	(*pub)->inner = g_steal_pointer (&pub_inner);
-
-	return TRUE;
- error:
-	egg_dh_privkey_free (*priv);
-	egg_dh_pubkey_free (*pub);
-
-	gcry_mpi_release (priv_inner);
-	gcry_mpi_release (pub_inner);
-
-	g_return_val_if_reached (FALSE);
-}
-
-GBytes *
-egg_dh_gen_secret (egg_dh_pubkey *peer, egg_dh_privkey *priv,
-                   egg_dh_params *params)
-{
-	gcry_error_t gcry;
-	guchar *value;
-	gsize n_prime;
-	gsize n_value;
-	gcry_mpi_t k;
-	gint bits;
-
-	g_return_val_if_fail (peer, NULL);
-	g_return_val_if_fail (priv, NULL);
-	g_return_val_if_fail (params, NULL);
-
-	bits = gcry_mpi_get_nbits (params->prime);
-	g_return_val_if_fail (bits >= 0, NULL);
-
-	k = gcry_mpi_snew (bits);
-	g_return_val_if_fail (k, NULL);
-	gcry_mpi_powm (k, peer->inner, priv->inner, params->prime);
-
-	/* Write out the secret */
-	gcry = gcry_mpi_print (GCRYMPI_FMT_USG, NULL, 0, &n_prime, params->prime);
-	g_return_val_if_fail (gcry == 0, NULL);
-	value = egg_secure_alloc (n_prime);
-	gcry = gcry_mpi_print (GCRYMPI_FMT_USG, value, n_prime, &n_value, k);
-	g_return_val_if_fail (gcry == 0, NULL);
-
-	/* Pad the secret with zero bytes to match length of prime in bytes. */
-	if (n_value < n_prime) {
-		memmove (value + (n_prime - n_value), value, n_value);
-		memset (value, 0, (n_prime - n_value));
-	}
-
-#if DEBUG_DH_SECRET
-	g_printerr ("DH SECRET: ");
-	gcry_mpi_dump (k);
-#endif
-	gcry_mpi_release (k);
-
-#if DEBUG_DH_SECRET
-	gcry_mpi_scan (&k, GCRYMPI_FMT_USG, value, n_prime, NULL);
-	g_printerr ("RAW SECRET: ");
-	gcry_mpi_dump (k);
-	gcry_mpi_release (k);
-#endif
-
-	return g_bytes_new_with_free_func (value, n_prime,
-					   (GDestroyNotify)egg_secure_free,
-					   value);
-}
-
-void
-egg_dh_params_free (egg_dh_params *params)
-{
-	if (!params)
-		return;
-	gcry_mpi_release (params->prime);
-	gcry_mpi_release (params->base);
-	g_free (params);
-}
-
-void
-egg_dh_pubkey_free (egg_dh_pubkey *pubkey)
-{
-	if (!pubkey)
-		return;
-	if (pubkey->inner)
-		gcry_mpi_release (pubkey->inner);
-	g_free (pubkey);
-}
-
-void
-egg_dh_privkey_free (egg_dh_privkey *privkey)
-{
-	if (!privkey)
-		return;
-	if (privkey->inner)
-		gcry_mpi_release (privkey->inner);
-	g_free (privkey);
-}
-
-GBytes *
-egg_dh_pubkey_export (const egg_dh_pubkey *pubkey)
-{
-	gcry_error_t gcry;
-	unsigned char *buffer;
-	size_t n_buffer;
-
-	gcry = gcry_mpi_aprint (GCRYMPI_FMT_USG, &buffer, &n_buffer,
-				pubkey->inner);
-	g_return_val_if_fail (gcry == 0, NULL);
-
-	return g_bytes_new_with_free_func (buffer, n_buffer,
-					   gcry_free, buffer);
-}
-
-egg_dh_pubkey *
-egg_dh_pubkey_new_from_bytes (const egg_dh_params *params,
-			      GBytes *bytes)
-{
-	gcry_error_t gcry;
-	gcry_mpi_t inner;
-	egg_dh_pubkey *pub;
-
-	gcry = gcry_mpi_scan (&inner, GCRYMPI_FMT_USG,
-			      g_bytes_get_data (bytes, NULL),
-			      g_bytes_get_size (bytes),
-			      NULL);
-	g_return_val_if_fail (gcry == 0, NULL);
-
-	pub = g_new (struct egg_dh_pubkey, 1);
-	if (!pub) {
-		gcry_mpi_release (inner);
-		g_return_val_if_reached (NULL);
-	}
-
-	pub->inner = inner;
-	return pub;
-}

egg/egg-dh.h

@@ -30,6 +30,17 @@ typedef struct egg_dh_params egg_dh_params;
 typedef struct egg_dh_pubkey egg_dh_pubkey;
 typedef struct egg_dh_privkey egg_dh_privkey;
 
+typedef struct egg_dh_group {
+	const gchar *name;
+	guint bits;
+	const guchar *prime;
+	gsize n_prime;
+	const guchar base[1];
+	gsize n_base;
+} egg_dh_group;
+
+extern const egg_dh_group egg_dh_groups[];
+
 egg_dh_params *egg_dh_default_params        (const gchar *name);
 
 gboolean       egg_dh_default_params_raw    (const gchar *name,

egg/egg-hkdf-gnutls.c

@@ -0,0 +1,110 @@
+/*
+ * libsecret
+ *
+ * Copyright (C) 2023 Daiki Ueno
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and
+ * the GNU Lesser General Public License along with this program.  If
+ * not, see http://www.gnu.org/licenses/.
+ *
+ * Author: Daiki Ueno
+ */
+
+#include "config.h"
+
+#include "egg-hkdf.h"
+
+#include "egg-secure-memory.h"
+#include <gnutls/crypto.h>
+
+EGG_SECURE_DECLARE (hkdf);
+
+gboolean
+egg_hkdf_perform (const gchar *hash_algo, gconstpointer input, gsize n_input,
+                  gconstpointer salt, gsize n_salt, gconstpointer info,
+                  gsize n_info, gpointer output, gsize n_output)
+{
+	static const struct {
+		gchar *name;
+		gnutls_mac_algorithm_t algo;
+	} hash_algos[] = {
+		{ "sha1", GNUTLS_MAC_SHA1 },
+		{ "sha256", GNUTLS_MAC_SHA256 },
+		{ NULL, }
+	};
+	gnutls_mac_algorithm_t algo = GNUTLS_MAC_UNKNOWN;
+	gnutls_datum_t input_datum, salt_datum, info_datum;
+	gpointer alloc = NULL;
+	gpointer buffer = NULL;
+	guint hash_len;
+	gsize i;
+	int ret;
+	gboolean result = TRUE;
+
+	for (i = 0; hash_algos[i].name; i++) {
+		if (g_str_equal (hash_algos[i].name, hash_algo)) {
+			algo = hash_algos[i].algo;
+			break;
+		}
+	}
+	g_return_val_if_fail (algo != GNUTLS_MAC_UNKNOWN, FALSE);
+
+	hash_len = gnutls_hmac_get_len (algo);
+	g_return_val_if_fail (hash_len != 0, FALSE);
+	g_return_val_if_fail (n_output <= 255 * hash_len, FALSE);
+
+	/* Buffer we need to for intermediate stuff */
+	buffer = egg_secure_alloc (hash_len);
+	g_return_val_if_fail (buffer, FALSE);
+
+	/* Salt defaults to hash_len zeros */
+	if (!salt) {
+		alloc = g_malloc0 (hash_len);
+		if (!alloc) {
+			result = FALSE;
+			goto out;
+		}
+		salt = alloc;
+		n_salt = hash_len;
+	}
+
+	/* Step 1: Extract */
+	input_datum.data = (void *)input;
+	input_datum.size = n_input;
+	salt_datum.data = (void *)salt;
+	salt_datum.size = n_salt;
+
+	ret = gnutls_hkdf_extract (algo, &input_datum, &salt_datum, buffer);
+	if (ret < 0) {
+		result = FALSE;
+		goto out;
+	}
+
+	/* Step 2: Expand */
+	input_datum.data = buffer;
+	input_datum.size = hash_len;
+	info_datum.data = (void *)info;
+	info_datum.size = n_info;
+
+	ret = gnutls_hkdf_expand (algo, &input_datum, &info_datum,
+				  output, n_output);
+	if (ret < 0) {
+		result = FALSE;
+		goto out;
+	}
+
+ out:
+	g_free (alloc);
+	egg_secure_free (buffer);
+	return result;
+}

egg/egg-hkdf-libgcrypt.c

@@ -13,10 +13,9 @@
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *  
- * You should have received a copy of the GNU Lesser General Public
+ * You should have received copies of the GNU General Public License and
- * License along with this program; if not, write to the Free Software
+ * the GNU Lesser General Public License along with this program.  If
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * not, see http://www.gnu.org/licenses/.
- * MA 02110-1301 USA
  *
  * Author: Stef Walter <stefw@collabora.co.uk>
  */
@@ -24,10 +23,8 @@
 #include "config.h"
 
 #include "egg-hkdf.h"
-#include "egg-secure-memory.h"
 
 #include <gcrypt.h>
-
 #include <string.h>
 
 gboolean

egg/egg-keyring1-gnutls.c

@@ -0,0 +1,156 @@
+/* libsecret - GLib wrapper for Secret Service
+ *
+ * Copyright 2019 Red Hat, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; either version 2.1 of the licence or (at
+ * your option) any later version.
+ *
+ * See the included COPYING file for more information.
+ *
+ * Author: Daiki Ueno
+ */
+
+#include "config.h"
+
+#include "egg-keyring1.h"
+
+#include "egg/egg-secure-memory.h"
+
+EGG_SECURE_DECLARE (egg_keyring1);
+
+#include <gnutls/crypto.h>
+#define PBKDF2_HASH_ALGO GNUTLS_MAC_SHA256
+#define MAC_ALGO GNUTLS_MAC_SHA256
+#define CIPHER_ALGO GNUTLS_CIPHER_AES_128_CBC
+
+void
+egg_keyring1_create_nonce (guint8 *nonce,
+			   gsize nonce_size)
+{
+	(void)gnutls_rnd (GNUTLS_RND_NONCE, nonce, nonce_size);
+}
+
+GBytes *
+egg_keyring1_derive_key (const char *password,
+			 gsize n_password,
+			 GBytes *salt,
+			 guint32 iteration_count)
+{
+	gnutls_datum_t password_datum, salt_datum;
+	guint8 *buffer;
+	int ret;
+
+	password_datum.data = (void *)password;
+	password_datum.size = n_password;
+
+	salt_datum.data = (void *)g_bytes_get_data (salt, NULL);
+	salt_datum.size = g_bytes_get_size (salt);
+
+	buffer = egg_secure_alloc (KEY_SIZE);
+	g_return_val_if_fail (buffer, NULL);
+
+	ret = gnutls_pbkdf2 (PBKDF2_HASH_ALGO, &password_datum, &salt_datum,
+			     iteration_count,
+			     buffer, KEY_SIZE);
+	if (ret < 0) {
+		egg_secure_free (buffer);
+		return NULL;
+	}
+
+	return g_bytes_new_with_free_func (buffer,
+					   KEY_SIZE,
+					   egg_secure_free,
+					   buffer);
+}
+
+gboolean
+egg_keyring1_calculate_mac (GBytes *key,
+			    const guint8 *value,
+			    gsize n_value,
+			    guint8 *buffer)
+{
+	return gnutls_hmac_fast (MAC_ALGO,
+				 g_bytes_get_data (key, NULL),
+				 g_bytes_get_size (key),
+				 value, n_value,
+				 buffer) >= 0;
+}
+
+gboolean
+egg_keyring1_verify_mac (GBytes *key,
+			 const guint8 *value,
+			 gsize n_value,
+			 const guint8 *data)
+{
+	guint8 buffer[MAC_SIZE];
+	guint8 status = 0;
+	gsize i;
+
+	if (!egg_keyring1_calculate_mac (key, value, n_value, buffer)) {
+		return FALSE;
+	}
+
+	for (i = 0; i < MAC_SIZE; i++) {
+		status |= data[i] ^ buffer[i];
+	}
+
+	return status == 0;
+}
+
+gboolean
+egg_keyring1_decrypt (GBytes *key,
+		      guint8 *data,
+		      gsize n_data)
+{
+	gnutls_cipher_hd_t hd = NULL;
+	int ret;
+	gsize n_secret;
+	gnutls_datum_t key_datum, iv_datum;
+
+	key_datum.data = (void *)g_bytes_get_data (key, &n_secret);
+	key_datum.size = n_secret;
+
+	iv_datum.data = data + n_data;
+	iv_datum.size = IV_SIZE;
+
+	ret = gnutls_cipher_init (&hd, CIPHER_ALGO, &key_datum, &iv_datum);
+	if (ret < 0) {
+		return FALSE;
+	}
+
+	ret = gnutls_cipher_decrypt2 (hd, data, n_data, data, n_data);
+	if (ret < 0) {
+		gnutls_cipher_deinit (hd);
+		return FALSE;
+	}
+
+	gnutls_cipher_deinit (hd);
+	return TRUE;
+}
+
+gboolean
+egg_keyring1_encrypt (GBytes *key,
+		      guint8 *data,
+		      gsize n_data)
+{
+	gnutls_cipher_hd_t hd = NULL;
+	int ret;
+	gsize n_secret;
+	gnutls_datum_t key_datum, iv_datum;
+
+	key_datum.data = (void *)g_bytes_get_data (key, &n_secret);
+	key_datum.size = n_secret;
+
+	iv_datum.data = data + n_data;
+	iv_datum.size = IV_SIZE;
+	egg_keyring1_create_nonce (iv_datum.data, iv_datum.size);
+
+	ret = gnutls_cipher_init (&hd, CIPHER_ALGO, &key_datum, &iv_datum);
+	g_return_val_if_fail (ret >= 0, FALSE);
+
+	ret = gnutls_cipher_encrypt2 (hd, data, n_data, data, n_data);
+	gnutls_cipher_deinit (hd);
+	return ret < 0 ? FALSE : TRUE;
+}

egg/meson.build

@@ -8,15 +8,27 @@ libegg_deps = [
   glib_deps,
 ]
 
-if get_option('gcrypt')
+if with_crypto
   libegg_sources += [
     'egg-dh.c',
-    'egg-hkdf.c',
-    'egg-keyring1.c',
-    'egg-libgcrypt.c',
   ]
 
-  libegg_deps += gcrypt_dep
+  if with_gcrypt
+    libegg_sources += [
+      'egg-dh-libgcrypt.c',
+      'egg-hkdf-libgcrypt.c',
+      'egg-keyring1-libgcrypt.c',
+      'egg-libgcrypt.c',
+    ]
+  elif with_gnutls
+    libegg_sources += [
+      'egg-dh-gnutls.c',
+      'egg-hkdf-gnutls.c',
+      'egg-keyring1-gnutls.c',
+    ]
+  endif
+
+  libegg_deps += crypto_deps
 endif
 
 if get_option('tpm2')
@@ -39,7 +51,7 @@ test_names = [
   'test-secmem',
 ]
 
-if get_option('gcrypt')
+if with_crypto
   test_names += [
     'test-dh',
     'test-hkdf',

egg/test-dh.c

@@ -33,7 +33,6 @@
 #include <string.h>
 
 #include <glib.h>
-#include <gcrypt.h>
 
 EGG_SECURE_DEFINE_GLIB_GLOBALS ();
 
@@ -107,10 +106,8 @@ static void
 check_dh_default (const gchar *name, guint bits)
 {
 	gboolean ret;
-	gcry_mpi_t check;
 	gconstpointer prime, base;
 	gsize n_prime, n_base;
-	gcry_error_t gcry;
 
 	ret = egg_dh_default_params_raw (name, &prime, &n_prime, &base, &n_base);
 	g_assert_true (ret);
@@ -118,14 +115,6 @@ check_dh_default (const gchar *name, guint bits)
 	egg_assert_cmpsize (n_prime, >, 0);
 	g_assert_nonnull (base);
 	egg_assert_cmpsize (n_base, >, 0);
-
-	gcry = gcry_mpi_scan (&check, GCRYMPI_FMT_USG, prime, n_prime, NULL);
-	g_assert_true (gcry == 0);
-	gcry_mpi_release (check);
-
-	gcry = gcry_mpi_scan (&check, GCRYMPI_FMT_USG, base, n_base, NULL);
-	g_assert_true (gcry == 0);
-	gcry_mpi_release (check);
 }
 
 static void

libsecret/meson.build

@@ -36,7 +36,7 @@ libsecret_headers = [
   'secret-value.h',
 ]
 
-if get_option('gcrypt')
+if with_crypto
   libsecret_sources += [
     'secret-file-backend.c',
     'secret-file-collection.c',
@@ -76,8 +76,8 @@ libsecret_dependencies = [
   glib_deps,
 ]
 
-if get_option('gcrypt')
+if with_crypto
-  libsecret_dependencies += gcrypt_dep
+  libsecret_dependencies += crypto_deps
 endif
 
 libsecret_cflags = [
@@ -231,7 +231,7 @@ test_names = [
   'test-collection',
 ]
 
-if get_option('gcrypt')
+if with_crypto
   test_names += [
     'test-file-collection',
   ]

libsecret/secret-backend.c

@@ -16,7 +16,7 @@
 
 #include "secret-backend.h"
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 #include "secret-file-backend.h"
 #endif
 
@@ -148,11 +148,11 @@ backend_get_impl_type (void)
 	GIOExtensionPoint *ep;
 
 	g_type_ensure (secret_service_get_type ());
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 	g_type_ensure (secret_file_backend_get_type ());
 #endif
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 	if ((g_file_test ("/.flatpak-info", G_FILE_TEST_EXISTS) || g_getenv ("SNAP_NAME") != NULL) &&
 	    _secret_file_backend_check_portal_version ())
 		extension_name = "file";

libsecret/secret-file-collection.c

@@ -17,11 +17,14 @@
 #include "secret-file-collection.h"
 
 #include "egg/egg-keyring1.h"
-#include "egg/egg-libgcrypt.h"
 #include "egg/egg-secure-memory.h"
 
 EGG_SECURE_DECLARE (secret_file_collection);
 
+#ifdef WITH_GCRYPT
+#include "egg/egg-libgcrypt.h"
+#endif
+
 #define KEYRING_FILE_HEADER "GnomeKeyring\n\r\0\n"
 #define KEYRING_FILE_HEADER_LEN 16
 
@@ -143,8 +146,9 @@ secret_file_collection_class_init (SecretFileCollectionClass *klass)
 		   g_param_spec_boxed ("password", "password", "Password",
 				       SECRET_TYPE_VALUE,
 				       G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY));
-
+#ifdef WITH_GCRYPT
 	egg_libgcrypt_initialize ();
+#endif
 }
 
 static gboolean

libsecret/secret-session.c

@@ -17,13 +17,20 @@
 
 #include "secret-private.h"
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 #include "egg/egg-dh.h"
 #include "egg/egg-hkdf.h"
+#endif
+
+#ifdef WITH_GCRYPT
 #include "egg/egg-libgcrypt.h"
 #include <gcrypt.h>
 #endif
 
+#ifdef WITH_GNUTLS
+#include <gnutls/crypto.h>
+#endif
+
 #include "egg/egg-hex.h"
 #include "egg/egg-secure-memory.h"
 
@@ -37,7 +44,7 @@ EGG_SECURE_DECLARE (secret_session);
 struct _SecretSession {
 	gchar *path;
 	const gchar *algorithms;
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 	egg_dh_params *params;
 	egg_dh_privkey *privat;
 	egg_dh_pubkey *publi;
@@ -55,7 +62,7 @@ _secret_session_free (gpointer data)
 		return;
 
 	g_free (session->path);
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 	egg_dh_pubkey_free (session->publi);
 	egg_dh_privkey_free (session->privat);
 	egg_dh_params_free (session->params);
@@ -64,7 +71,7 @@ _secret_session_free (gpointer data)
 	g_free (session);
 }
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 
 static GVariant *
 request_open_session_aes (SecretSession *session)
@@ -76,7 +83,9 @@ request_open_session_aes (SecretSession *session)
 	g_assert (session->privat == NULL);
 	g_assert (session->publi == NULL);
 
+#ifdef WITH_GCRYPT
 	egg_libgcrypt_initialize ();
+#endif
 
 	/* Initialize our local parameters and values */
 	session->params = egg_dh_default_params ("ietf-ike-grp-modp-1024");
@@ -168,7 +177,7 @@ response_open_session_aes (SecretSession *session,
 	return TRUE;
 }
 
-#endif /* WITH_GCRYPT */
+#endif /* WITH_CRYPTO */
 
 static GVariant *
 request_open_session_plain (SecretSession *session)
@@ -251,7 +260,7 @@ on_service_open_session_plain (GObject *source,
 	g_object_unref (task);
 }
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 
 static void
 on_service_open_session_aes (GObject *source,
@@ -300,7 +309,7 @@ on_service_open_session_aes (GObject *source,
 	g_object_unref (task);
 }
 
-#endif /* WITH_GCRYPT */
+#endif /* WITH_CRYPTO */
 
 
 void
@@ -319,7 +328,7 @@ _secret_session_open (SecretService *service,
 	g_task_set_task_data (task, closure, open_session_closure_free);
 
 	g_dbus_proxy_call (G_DBUS_PROXY (service), "OpenSession",
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 	                   request_open_session_aes (closure->session),
 	                   G_DBUS_CALL_FLAGS_NONE, -1,
 	                   cancellable, on_service_open_session_aes,
@@ -345,7 +354,7 @@ _secret_session_open_finish (GAsyncResult *result,
 	return TRUE;
 }
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 
 static gboolean
 pkcs7_unpad_bytes_in_place (guchar *padded,
@@ -377,6 +386,8 @@ pkcs7_unpad_bytes_in_place (guchar *padded,
 	return TRUE;
 }
 
+#ifdef WITH_GCRYPT
+
 static SecretValue *
 service_decode_aes_secret (SecretSession *session,
                            gconstpointer param,
@@ -447,6 +458,85 @@ service_decode_aes_secret (SecretSession *session,
 
 #endif /* WITH_GCRYPT */
 
+#ifdef WITH_GNUTLS
+
+static SecretValue *
+service_decode_aes_secret (SecretSession *session,
+                           gconstpointer param,
+                           gsize n_param,
+                           gconstpointer value,
+                           gsize n_value,
+                           const gchar *content_type)
+{
+	gnutls_cipher_hd_t cih;
+	gnutls_datum_t iv, key;
+	gsize n_padded;
+	int ret;
+	guchar *padded;
+
+	if (n_param != 16) {
+		g_info ("received an encrypted secret structure with invalid parameter");
+		return NULL;
+	}
+
+	if (n_value == 0 || n_value % 16 != 0) {
+		g_info ("received an encrypted secret structure with bad secret length");
+		return NULL;
+	}
+
+#if 0
+	g_printerr ("    lib iv:  %s\n", egg_hex_encode (param, n_param));
+#endif
+
+#if 0
+	g_printerr ("   lib key:  %s\n", egg_hex_encode (session->key, session->n_key));
+#endif
+
+	iv.data = (void *)param;
+	iv.size = n_param;
+	key.data = session->key;
+	key.size = session->n_key;
+	ret = gnutls_cipher_init (&cih, GNUTLS_CIPHER_AES_128_CBC, &key, &iv);
+	if (ret != 0) {
+		g_warning ("couldn't create AES cipher: %s", gnutls_strerror (ret));
+		return NULL;
+	}
+
+	/* Copy the memory buffer */
+	n_padded = n_value;
+	padded = egg_secure_alloc (n_padded);
+	if (!padded) {
+		gnutls_cipher_deinit (cih);
+		return NULL;
+	}
+	memcpy (padded, value, n_padded);
+
+	/* Perform the decryption */
+	ret = gnutls_cipher_decrypt2 (cih, padded, n_padded, padded, n_padded);
+	if (ret < 0) {
+		egg_secure_clear (padded, n_padded);
+		egg_secure_free (padded);
+		gnutls_cipher_deinit (cih);
+		return NULL;
+	}
+
+	gnutls_cipher_deinit (cih);
+
+	/* Unpad the resulting value */
+	if (!pkcs7_unpad_bytes_in_place (padded, &n_padded)) {
+		egg_secure_clear (padded, n_padded);
+		egg_secure_free (padded);
+		g_info ("received an invalid or unencryptable secret");
+		return FALSE;
+	}
+
+	return secret_value_new_full ((gchar *)padded, n_padded, content_type, egg_secure_free);
+}
+
+#endif /* WITH_GNUTLS */
+
+#endif /* WITH_CRYPTO */
+
 static SecretValue *
 service_decode_plain_secret (SecretSession *session,
                              gconstpointer param,
@@ -496,7 +586,7 @@ _secret_session_decode_secret (SecretSession *session,
 	value = g_variant_get_fixed_array (vvalue, &n_value, sizeof (guchar));
 	g_variant_get_child (encoded, 3, "s", &content_type);
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 	if (session->key != NULL)
 		result = service_decode_aes_secret (session, param, n_param,
 		                                    value, n_value, content_type);
@@ -513,7 +603,7 @@ _secret_session_decode_secret (SecretSession *session,
 	return result;
 }
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 
 static guchar*
 pkcs7_pad_bytes_in_secure_memory (gconstpointer secret,
@@ -535,6 +625,8 @@ pkcs7_pad_bytes_in_secure_memory (gconstpointer secret,
 	return padded;
 }
 
+#ifdef WITH_GCRYPT
+
 static gboolean
 service_encode_aes_secret (SecretSession *session,
                            SecretValue *value,
@@ -594,6 +686,72 @@ service_encode_aes_secret (SecretSession *session,
 
 #endif /* WITH_GCRYPT */
 
+#ifdef WITH_GNUTLS
+
+static gboolean
+service_encode_aes_secret (SecretSession *session,
+                           SecretValue *value,
+                           GVariantBuilder *builder)
+{
+	gnutls_cipher_hd_t cih = NULL;
+	guchar *padded;
+	gsize n_padded;
+	int ret;
+	gnutls_datum_t iv, key;
+	gpointer iv_data;
+	gconstpointer secret;
+	gsize n_secret;
+	GVariant *child;
+
+	g_variant_builder_add (builder, "o", session->path);
+
+	secret = secret_value_get (value, &n_secret);
+
+	/* Perform the encoding here */
+	padded = pkcs7_pad_bytes_in_secure_memory (secret, n_secret, &n_padded);
+	g_assert (padded != NULL);
+
+	/* Setup the IV */
+	iv_data = g_malloc0 (16);
+	iv.data = iv_data;
+	iv.size = 16;
+	ret = gnutls_rnd (GNUTLS_RND_NONCE, iv.data, iv.size);
+	g_return_val_if_fail (ret >= 0, FALSE);
+
+	/* Setup the key */
+	key.data = session->key;
+	key.size = session->n_key;
+
+	/* Create the cipher */
+	ret = gnutls_cipher_init (&cih, GNUTLS_CIPHER_AES_128_CBC, &key, &iv);
+	if (ret < 0) {
+		g_warning ("couldn't create AES cipher: %s", gnutls_strerror (ret));
+		return FALSE;
+	}
+
+	/* Perform the encryption */
+	ret = gnutls_cipher_encrypt2 (cih, padded, n_padded, padded, n_padded);
+	if (ret < 0) {
+		gnutls_cipher_deinit (cih);
+		return FALSE;
+	}
+
+	gnutls_cipher_deinit (cih);
+
+	child = g_variant_new_from_data (G_VARIANT_TYPE ("ay"), iv_data, 16, TRUE, g_free, iv_data);
+	g_variant_builder_add_value (builder, child);
+
+	child = g_variant_new_from_data (G_VARIANT_TYPE ("ay"), padded, n_padded, TRUE, egg_secure_free, padded);
+	g_variant_builder_add_value (builder, child);
+
+	g_variant_builder_add (builder, "s", secret_value_get_content_type (value));
+	return TRUE;
+}
+
+#endif /* WITH_GNUTLS */
+
+#endif /* WITH_CRYPTO */
+
 static gboolean
 service_encode_plain_secret (SecretSession *session,
                              SecretValue *value,
@@ -633,7 +791,7 @@ _secret_session_encode_secret (SecretSession *session,
 	type = g_variant_type_new ("(oayays)");
 	builder = g_variant_builder_new (type);
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 	if (session->key)
 		ret = service_encode_aes_secret (session, value, builder);
 	else

libsecret/test-session.c

@@ -29,7 +29,7 @@
 #include <errno.h>
 #include <stdlib.h>
 
-#ifdef WITH_GCRYPT
+#ifdef WITH_CRYPTO
 #define SESSION_ALGO "dh-ietf1024-sha256-aes128-cbc-pkcs7"
 #else
 #define SESSION_ALGO "plain"

meson.build

@@ -30,11 +30,37 @@ glib_deps = [
   dependency('gio-unix-2.0', version: '>=' + min_glib_version),
 ]
 
+with_gcrypt = false
+with_gnutls = false
+with_crypto = false
+
+crypto_deps = []
+
+if get_option('crypto') == 'libgcrypt'
   min_libgcrypt_version = '1.2.2'
-gcrypt_dep = dependency('libgcrypt',
+  gcrypt_dep = dependency(
+    'libgcrypt',
     version: '>=' + min_libgcrypt_version,
-  required: get_option('gcrypt'),
+    required: false,
   )
+  if gcrypt_dep.found()
+    with_gcrypt = true
+    with_crypto = true
+    crypto_deps += gcrypt_dep
+  endif
+elif get_option('crypto') == 'gnutls'
+  min_gnutls_version = '3.8.2'
+  gnutls_dep = dependency(
+    'gnutls',
+    version: '>=' + min_gnutls_version,
+    required: false,
+  )
+  if gnutls_dep.found()
+    with_gnutls = true
+    with_crypto = true
+    crypto_deps += gnutls_dep
+  endif
+endif
 
 min_tss2_version = '3.0.3'
 tss2_esys = dependency('tss2-esys', version: '>=' + min_tss2_version, required: get_option('tpm2'))
@@ -58,9 +84,11 @@ conf.set_quoted('LOCALEDIR', libsecret_prefix / get_option('localedir'))
 conf.set_quoted('PACKAGE_NAME', meson.project_name())
 conf.set_quoted('PACKAGE_STRING', meson.project_name())
 conf.set_quoted('PACKAGE_VERSION', meson.project_version())
-conf.set('WITH_GCRYPT', get_option('gcrypt'))
+conf.set('WITH_GCRYPT', with_gcrypt)
+conf.set('WITH_GNUTLS', with_gnutls)
+conf.set('WITH_CRYPTO', with_crypto)
 conf.set('WITH_TPM', get_option('tpm2'))
-if get_option('gcrypt')
+if with_gcrypt
   conf.set_quoted('LIBGCRYPT_VERSION', min_libgcrypt_version)
 endif
 if get_option('tpm2')

meson_options.txt

@@ -1,5 +1,5 @@
 option('manpage', type: 'boolean', value: true, description: 'Build man pages')
-option('gcrypt', type: 'boolean', value: true, description: 'With gcrypt and transport encryption')
+option('crypto', type: 'combo', choices: ['libgcrypt', 'gnutls', 'disabled'], value: 'libgcrypt', description: 'Backend library to implement transport encryption')
 option('debugging', type: 'boolean', value: false, description: 'Turn debugging on/off')
 option('vapi', type: 'boolean', value: true, description: 'Create VAPI file.')
 option('gtk_doc', type: 'boolean', value: true, description: 'Build reference documentation using gi-docgen')

tool/meson.build

@@ -10,7 +10,7 @@ secret_tool = executable('secret-tool',
   install: true,
 )
 
-if get_option('gcrypt') and host_machine.system() != 'windows'
+if with_crypto and host_machine.system() != 'windows'
   test('test-secret-tool.sh',
     find_program('test-secret-tool.sh'),
     env: test_env,