1 files changed, 37 insertions, 0 deletions
diff --git a/crypto/hmac.c b/crypto/hmac.c
new file mode 100644
index 0000000..f9b81c1
--- /dev/null
+++ b/crypto/hmac.c
@@ -0,0 +1,37 @@
+#include "hmac.h"
+
+/* function doing the HMAC-SHA-1 calculation */
+void hmac_sha1(const uint8_t* key, const uint32_t keysize, const uint8_t* msg, const uint32_t msgsize, uint8_t* output)
+{
+  struct sha1 outer, inner;
+  uint8_t tmp;
+
+  sha1_reset(&outer);
+  sha1_reset(&inner);
+
+  uint32_t i;
+  for (i = 0; i < keysize; ++i)
+  {
+    tmp = key[i] ^ 0x5C;
+    sha1_input(&outer, &tmp, 1);
+    tmp = key[i] ^ 0x36;
+    sha1_input(&inner, &tmp, 1);
+  }
+  for (; i < 64; ++i)
+  {
+    tmp = 0x5C;
+    sha1_input(&outer, &tmp, 1);
+    tmp = 0x36;
+    sha1_input(&inner, &tmp, 1);
+  }
+
+  sha1_input(&inner, msg, msgsize);
+  sha1_result(&inner, output);
+
+  sha1_input(&outer, output, HMAC_SHA1_HASH_SIZE);
+  sha1_result(&outer, output);
+}
+
+
+
+