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-rw-r--r--cmac_gnutls.c189
1 files changed, 189 insertions, 0 deletions
diff --git a/cmac_gnutls.c b/cmac_gnutls.c
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--- /dev/null
+++ b/cmac_gnutls.c
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+/*
+ chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar 2021
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ **********************************************************************
+
+ =======================================================================
+
+ CMAC using the GnuTLS library
+ */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "cmac.h"
+#include "hash.h"
+#include "logging.h"
+#include "memory.h"
+
+struct CMC_Instance_Record {
+ gnutls_mac_algorithm_t algorithm;
+ gnutls_hmac_hd_t mac;
+};
+
+/* ================================================== */
+
+static int instance_counter = 0;
+static int gnutls_initialised = 0;
+
+/* ================================================== */
+
+static void
+init_gnutls(void)
+{
+ int r;
+
+ if (gnutls_initialised)
+ return;
+
+ r = gnutls_global_init();
+ if (r < 0)
+ LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
+
+ DEBUG_LOG("Initialised");
+ gnutls_initialised = 1;
+}
+
+/* ================================================== */
+
+static void
+deinit_gnutls(void)
+{
+ assert(gnutls_initialised);
+ gnutls_global_deinit();
+ gnutls_initialised = 0;
+ DEBUG_LOG("Deinitialised");
+}
+
+/* ================================================== */
+
+static gnutls_mac_algorithm_t
+get_mac_algorithm(CMC_Algorithm algorithm)
+{
+ switch (algorithm) {
+ case CMC_AES128:
+ return GNUTLS_MAC_AES_CMAC_128;
+ case CMC_AES256:
+ return GNUTLS_MAC_AES_CMAC_256;
+ default:
+ return GNUTLS_MAC_UNKNOWN;
+ }
+}
+
+/* ================================================== */
+
+int
+CMC_GetKeyLength(CMC_Algorithm algorithm)
+{
+ gnutls_mac_algorithm_t malgo = get_mac_algorithm(algorithm);
+ int len;
+
+ if (malgo == GNUTLS_MAC_UNKNOWN)
+ return 0;
+
+ len = gnutls_hmac_get_key_size(malgo);
+
+ if (len < 0)
+ return 0;
+
+ return len;
+}
+
+/* ================================================== */
+
+CMC_Instance
+CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
+{
+ gnutls_hmac_hd_t handle;
+ CMC_Instance inst;
+
+ int r;
+
+ if (instance_counter == 0)
+ init_gnutls();
+
+ if (length <= 0 || length != CMC_GetKeyLength(algorithm))
+ goto error;
+
+ r = gnutls_hmac_init(&handle, get_mac_algorithm(algorithm), key, length);
+ if (r < 0) {
+ DEBUG_LOG("Could not initialise %s : %s", "mac", gnutls_strerror(r));
+ goto error;
+ }
+
+ inst = MallocNew(struct CMC_Instance_Record);
+ inst->algorithm = get_mac_algorithm(algorithm);
+ inst->mac = handle;
+
+ instance_counter++;
+
+ return inst;
+
+error:
+ if (instance_counter == 0)
+ deinit_gnutls();
+ return NULL;
+}
+
+/* ================================================== */
+
+int
+CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
+{
+ unsigned char buf[MAX_HASH_LENGTH];
+ int hash_len;
+
+ if (in_len < 0 || out_len < 0)
+ return 0;
+
+ hash_len = gnutls_hmac_get_len(inst->algorithm);
+
+ if (out_len > hash_len)
+ out_len = hash_len;
+
+ if (hash_len > sizeof (buf))
+ return 0;
+
+ if (gnutls_hmac(inst->mac, in, in_len) < 0) {
+ /* Reset the state */
+ gnutls_hmac_output(inst->mac, buf);
+ return 0;
+ }
+
+ gnutls_hmac_output(inst->mac, buf);
+ memcpy(out, buf, out_len);
+
+ return out_len;
+}
+
+/* ================================================== */
+
+void
+CMC_DestroyInstance(CMC_Instance inst)
+{
+ gnutls_hmac_deinit(inst->mac, NULL);
+ Free(inst);
+
+ instance_counter--;
+ if (instance_counter == 0)
+ deinit_gnutls();
+}