1 files changed, 156 insertions, 0 deletions
diff --git a/siv_nettle.c b/siv_nettle.c
new file mode 100644
index 0000000..d8f8b23
--- /dev/null
+++ b/siv_nettle.c
@@ -0,0 +1,156 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * 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 Nettle library
+  */
+
+#include "config.h"
+
+#include "sysincl.h"
+
+#ifdef HAVE_NETTLE_SIV_CMAC
+#include <nettle/siv-cmac.h>
+#else
+#include "siv_nettle_int.c"
+#endif
+
+#include "memory.h"
+#include "siv.h"
+
+struct SIV_Instance_Record {
+  struct siv_cmac_aes128_ctx siv;
+  int key_set;
+};
+
+/* ================================================== */
+
+SIV_Instance
+SIV_CreateInstance(SIV_Algorithm algorithm)
+{
+  SIV_Instance instance;
+
+  if (algorithm != AEAD_AES_SIV_CMAC_256)
+    return NULL;
+
+  instance = MallocNew(struct SIV_Instance_Record);
+  instance->key_set = 0;
+
+  return instance;
+}
+
+/* ================================================== */
+
+void
+SIV_DestroyInstance(SIV_Instance instance)
+{
+  Free(instance);
+}
+
+/* ================================================== */
+
+int
+SIV_GetKeyLength(SIV_Algorithm algorithm)
+{
+  assert(32 <= SIV_MAX_KEY_LENGTH);
+
+  if (algorithm == AEAD_AES_SIV_CMAC_256)
+    return 32;
+  return 0;
+}
+
+/* ================================================== */
+
+int
+SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length)
+{
+  if (length != 32)
+    return 0;
+
+  siv_cmac_aes128_set_key(&instance->siv, key);
+
+  instance->key_set = 1;
+
+  return 1;
+}
+
+/* ================================================== */
+
+int
+SIV_GetTagLength(SIV_Instance instance)
+{
+  assert(SIV_DIGEST_SIZE <= SIV_MAX_TAG_LENGTH);
+
+  return SIV_DIGEST_SIZE;
+}
+
+/* ================================================== */
+
+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)
+{
+  if (!instance->key_set)
+    return 0;
+
+  if (nonce_length < SIV_MIN_NONCE_SIZE || assoc_length < 0 ||
+      plaintext_length < 0 || plaintext_length > ciphertext_length ||
+      plaintext_length + SIV_DIGEST_SIZE != ciphertext_length)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  siv_cmac_aes128_encrypt_message(&instance->siv, nonce_length, nonce,
+                                  assoc_length, assoc,
+                                  ciphertext_length, ciphertext, plaintext);
+  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)
+{
+  if (!instance->key_set)
+    return 0;
+
+  if (nonce_length < SIV_MIN_NONCE_SIZE || assoc_length < 0 ||
+      plaintext_length < 0 || plaintext_length > ciphertext_length ||
+      plaintext_length + SIV_DIGEST_SIZE != ciphertext_length)
+    return 0;
+
+  assert(assoc && plaintext);
+
+  if (!siv_cmac_aes128_decrypt_message(&instance->siv, nonce_length, nonce,
+                                       assoc_length, assoc,
+                                       plaintext_length, plaintext, ciphertext))
+    return 0;
+
+  return 1;
+}