Diff: hmac.c

Revision:

0:ff9ebe0cf0e9

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hmac.c	Fri Oct 18 13:18:30 2013 +0000
@@ -0,0 +1,168 @@
+/* dtls -- a very basic DTLS implementation
+ *
+ * Copyright (C) 2011--2012 Olaf Bergmann <bergmann@tzi.org>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#ifdef HAVE_ASSERT_H
+#include <assert.h>
+#endif
+
+#include "debug.h"
+#include "hmac.h"
+
+/* use malloc()/free() on platforms other than Contiki */
+#ifndef WITH_CONTIKI
+#include <stdlib.h>
+
+static inline dtls_hmac_context_t *
+dtls_hmac_context_new() {
+  return (dtls_hmac_context_t *)malloc(sizeof(dtls_hmac_context_t));
+}
+
+static inline void
+dtls_hmac_context_free(dtls_hmac_context_t *ctx) {
+  free(ctx);
+}
+
+#else /* WITH_CONTIKI */
+#include "memb.h"
+MEMB(hmac_context_storage, dtls_hmac_context_t, DTLS_HASH_MAX);
+
+static inline dtls_hmac_context_t *
+dtls_hmac_context_new() {
+  return (dtls_hmac_context_t *)memb_alloc(&hmac_context_storage);
+}
+
+static inline void
+dtls_hmac_context_free(dtls_hmac_context_t *ctx) {
+  memb_free(&hmac_context_storage, ctx);
+}
+
+void
+dtls_hmac_storage_init() {
+  memb_init(&hmac_context_storage);
+}
+#endif /* WITH_CONTIKI */
+
+void
+dtls_hmac_update(dtls_hmac_context_t *ctx,
+		 const unsigned char *input, size_t ilen) {
+  assert(ctx);
+  dtls_hash_update(&ctx->data, input, ilen);
+}
+
+dtls_hmac_context_t *
+dtls_hmac_new(const unsigned char *key, size_t klen) {
+  dtls_hmac_context_t *ctx;
+
+  ctx = dtls_hmac_context_new();
+  if (ctx) 
+    dtls_hmac_init(ctx, key, klen);
+
+  return ctx;
+}
+
+void
+dtls_hmac_init(dtls_hmac_context_t *ctx, const unsigned char *key, size_t klen) {
+  int i;
+
+  assert(ctx);
+
+  memset(ctx, 0, sizeof(dtls_hmac_context_t));
+
+  if (klen > DTLS_HMAC_BLOCKSIZE) {
+    dtls_hash_init(&ctx->data);
+    dtls_hash_update(&ctx->data, key, klen);
+    dtls_hash_finalize(ctx->pad, &ctx->data);
+  } else
+    memcpy(ctx->pad, key, klen);
+
+  /* create ipad: */
+  for (i=0; i < DTLS_HMAC_BLOCKSIZE; ++i)
+    ctx->pad[i] ^= 0x36;
+
+  dtls_hash_init(&ctx->data);
+  dtls_hmac_update(ctx, ctx->pad, DTLS_HMAC_BLOCKSIZE);
+
+  /* create opad by xor-ing pad[i] with 0x36 ^ 0x5C: */
+  for (i=0; i < DTLS_HMAC_BLOCKSIZE; ++i)
+    ctx->pad[i] ^= 0x6A;
+}
+
+void
+dtls_hmac_free(dtls_hmac_context_t *ctx) {
+  if (ctx)
+    dtls_hmac_context_free(ctx);
+}
+
+int
+dtls_hmac_finalize(dtls_hmac_context_t *ctx, unsigned char *result) {
+  unsigned char buf[DTLS_HMAC_DIGEST_SIZE];
+  size_t len; 
+
+  assert(ctx);
+  assert(result);
+  
+  len = dtls_hash_finalize(buf, &ctx->data);
+
+  dtls_hash_init(&ctx->data);
+  dtls_hash_update(&ctx->data, ctx->pad, DTLS_HMAC_BLOCKSIZE);
+  dtls_hash_update(&ctx->data, buf, len);
+
+  len = dtls_hash_finalize(result, &ctx->data);
+
+  return len;
+}
+
+#ifdef HMAC_TEST
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  static unsigned char buf[DTLS_HMAC_DIGEST_SIZE];
+  size_t len, i;
+  dtls_hmac_context_t *ctx;
+
+  if (argc < 3) {
+    fprintf(stderr, "usage: %s key text", argv[0]);
+    return -1;
+  }
+
+  dtls_hmac_storage_init();
+  ctx = dtls_hmac_new(argv[1], strlen(argv[1]));
+  assert(ctx);
+  dtls_hmac_update(ctx, argv[2], strlen(argv[2]));
+  
+  len = dtls_hmac_finalize(ctx, buf);
+
+  for(i = 0; i < len; i++) 
+    printf("%02x", buf[i]);
+  printf("\n");
+
+  dtls_hmac_free(ctx);
+
+  return 0;
+}
+#endif