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-rw-r--r--siv_gnutls.c271
1 files changed, 271 insertions, 0 deletions
diff --git a/siv_gnutls.c b/siv_gnutls.c
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+++ b/siv_gnutls.c
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+/*
+ chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar 2020
+ *
+ * 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.
+ *
+ **********************************************************************
+
+ =======================================================================
+
+ SIV ciphers using the GnuTLS library
+ */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#include <gnutls/crypto.h>
+
+#include "logging.h"
+#include "memory.h"
+#include "siv.h"
+
+struct SIV_Instance_Record {
+ gnutls_cipher_algorithm_t algorithm;
+ gnutls_aead_cipher_hd_t cipher;
+};
+
+/* ================================================== */
+
+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_cipher_algorithm_t
+get_cipher_algorithm(SIV_Algorithm algorithm)
+{
+ switch (algorithm) {
+ case AEAD_AES_SIV_CMAC_256:
+ return GNUTLS_CIPHER_AES_128_SIV;
+ default:
+ return 0;
+ }
+}
+
+/* ================================================== */
+
+SIV_Instance
+SIV_CreateInstance(SIV_Algorithm algorithm)
+{
+ gnutls_cipher_algorithm_t calgo;
+ SIV_Instance instance;
+
+ calgo = get_cipher_algorithm(algorithm);
+ if (calgo == 0)
+ return NULL;
+
+ if (instance_counter == 0)
+ init_gnutls();
+
+ /* Check if the cipher is actually supported */
+ if (gnutls_cipher_get_tag_size(calgo) == 0) {
+ if (instance_counter == 0)
+ deinit_gnutls();
+ return NULL;
+ }
+
+ instance = MallocNew(struct SIV_Instance_Record);
+ instance->algorithm = calgo;
+ instance->cipher = NULL;
+
+ instance_counter++;
+
+ return instance;
+}
+
+/* ================================================== */
+
+void
+SIV_DestroyInstance(SIV_Instance instance)
+{
+ if (instance->cipher)
+ gnutls_aead_cipher_deinit(instance->cipher);
+ Free(instance);
+
+ instance_counter--;
+ if (instance_counter == 0)
+ deinit_gnutls();
+}
+
+/* ================================================== */
+
+int
+SIV_GetKeyLength(SIV_Algorithm algorithm)
+{
+ gnutls_cipher_algorithm_t calgo = get_cipher_algorithm(algorithm);
+ int len;
+
+ if (calgo == 0)
+ return 0;
+
+ len = gnutls_cipher_get_key_size(calgo);
+
+ if (len < 1 || len > SIV_MAX_KEY_LENGTH)
+ LOG_FATAL("Invalid key length");
+
+ return len;
+}
+
+/* ================================================== */
+
+int
+SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length)
+{
+ gnutls_aead_cipher_hd_t cipher;
+ gnutls_datum_t datum;
+ int r;
+
+ if (length <= 0 || length != gnutls_cipher_get_key_size(instance->algorithm))
+ return 0;
+
+ datum.data = (unsigned char *)key;
+ datum.size = length;
+
+#ifdef HAVE_GNUTLS_AEAD_CIPHER_SET_KEY
+ if (instance->cipher) {
+ r = gnutls_aead_cipher_set_key(instance->cipher, &datum);
+ if (r < 0) {
+ DEBUG_LOG("Could not set cipher key : %s", gnutls_strerror(r));
+ return 0;
+ }
+
+ return 1;
+ }
+#endif
+
+ /* Initialise a new cipher with the provided key */
+ r = gnutls_aead_cipher_init(&cipher, instance->algorithm, &datum);
+ if (r < 0) {
+ DEBUG_LOG("Could not initialise %s : %s", "cipher", gnutls_strerror(r));
+ return 0;
+ }
+
+ /* Destroy the previous cipher (if its key could not be changed directly) */
+ if (instance->cipher)
+ gnutls_aead_cipher_deinit(instance->cipher);
+
+ instance->cipher = cipher;
+
+ return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_GetTagLength(SIV_Instance instance)
+{
+ int len;
+
+ len = gnutls_cipher_get_tag_size(instance->algorithm);
+
+ if (len < 1 || len > SIV_MAX_TAG_LENGTH)
+ LOG_FATAL("Invalid tag length");
+
+ return len;
+}
+
+/* ================================================== */
+
+int
+SIV_Encrypt(SIV_Instance instance,
+ const unsigned char *nonce, int nonce_length,
+ const void *assoc, int assoc_length,
+ const void *plaintext, int plaintext_length,
+ unsigned char *ciphertext, int ciphertext_length)
+{
+ size_t clen = ciphertext_length;
+
+ if (!instance->cipher)
+ return 0;
+
+ if (nonce_length < 1 || assoc_length < 0 ||
+ plaintext_length < 0 || ciphertext_length < 0)
+ return 0;
+
+ assert(assoc && plaintext);
+
+ if (gnutls_aead_cipher_encrypt(instance->cipher,
+ nonce, nonce_length, assoc, assoc_length, 0,
+ plaintext, plaintext_length, ciphertext, &clen) < 0)
+ return 0;
+
+ if (clen != ciphertext_length)
+ return 0;
+
+ return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_Decrypt(SIV_Instance instance,
+ const unsigned char *nonce, int nonce_length,
+ const void *assoc, int assoc_length,
+ const unsigned char *ciphertext, int ciphertext_length,
+ void *plaintext, int plaintext_length)
+{
+ size_t plen = plaintext_length;
+
+ if (!instance->cipher)
+ return 0;
+
+ if (nonce_length < 1 || assoc_length < 0 ||
+ plaintext_length < 0 || ciphertext_length < 0)
+ return 0;
+
+ assert(assoc && plaintext);
+
+ if (gnutls_aead_cipher_decrypt(instance->cipher,
+ nonce, nonce_length, assoc, assoc_length, 0,
+ ciphertext, ciphertext_length, plaintext, &plen) < 0)
+ return 0;
+
+ if (plen != plaintext_length)
+ return 0;
+
+ return 1;
+}