Add generic wrappers for performing message digest operations.

src/platform/vboot_reference/tests/verify_data.c

Index: src/platform/vboot_reference/tests/verify_data.c
diff --git a/src/platform/vboot_reference/tests/verify_data.c b/src/platform/vboot_reference/tests/verify_data.c
index ac51dafaf1749cb10bcb65ec19e961bf73376e61..f191606cd6b83b2eb6056ff6cfccbeade398619d 100644
--- a/src/platform/vboot_reference/tests/verify_data.c
+++ b/src/platform/vboot_reference/tests/verify_data.c
@@ -15,7 +15,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-#include "digest_utility.h"
+#include "sha_utility.h"
 #include "padding.h"
 #include "rsa.h"
 #include "rsa_utility.h"
@@ -105,7 +105,7 @@ int main(int argc, char* argv[]) {
     goto failure;
   if (!(signature = read_signature(argv[3], sig_len)))
     goto failure;
-  if (!(digest = calculate_digest(argv[4], algorithm)))
+  if (!(digest = DigestFile(argv[4], algorithm)))
     goto failure;
   if(RSA_verify(key, signature, sig_len, algorithm, digest))
     fprintf(stderr, "Signature Verification SUCCEEDED.\n");