Merge pull request #545 from tock/hmac-test-update

tests: hmac: add check for correctness

Author: ppannuto

examples/tests/hmac/README.md

@@ -2,3 +2,13 @@ HMAC
 ====
 
 This test performs a HMAC operation on a string and prints the output
+
+Expected Output
+---------------
+
+```
+[TEST] HMAC
+[HMAC] Computed Output: b5055553bd5e75d4fc96bf2559d655b77a58aea8b4c4076c52f774851bba06d8
+[HMAC] Expected Output: b5055553bd5e75d4fc96bf2559d655b77a58aea8b4c4076c52f774851bba06d8
+[HMAC] Matched!
+```

examples/tests/hmac/main.c

@@ -11,6 +11,8 @@
 uint8_t key_buf[KEY_LEN]   = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0xA0, 0xA1};
 uint8_t data_buf[DATA_LEN] = "A language empowering everyone to build reliable and efficient software.";
 uint8_t dest_buf[DEST_LEN];
+uint8_t expected_output[DEST_LEN] = {0xb5, 0x05, 0x55, 0x53, 0xbd, 0x5e, 0x75, 0xd4, 0xfc, 0x96, 0xbf, 0x25, 0x59, 0xd6,
+  0x55, 0xb7, 0x7a, 0x58, 0xae, 0xa8, 0xb4, 0xc4, 0x07, 0x6c, 0x52, 0xf7, 0x74, 0x85, 0x1b, 0xba, 0x06, 0xd8};
 
 
 
@@ -32,5 +34,30 @@ int main(void) {
     return -1;
   }
 
+  bool match = true;
+
+  printf("[HMAC] Computed Output: ");
+  for (int i = 0; i < DEST_LEN; i++) {
+    printf("%02x", dest_buf[i]);
+
+    if (dest_buf[i] != expected_output[i]) {
+      match = false;
+    }
+  }
+  printf("\n");
+
+  printf("[HMAC] Expected Output: ");
+  for (int i = 0; i < DEST_LEN; i++) {
+    printf("%02x", expected_output[i]);
+  }
+  printf("\n");
+
+  printf("[HMAC] ");
+  if (match) {
+    printf("Matched!\n");
+  } else {
+    printf("Error! Computation was incorrect!\n");
+  }
+
   return 0;
 }