Add utility to pad a given hash for PKCS1.5 signatures

utility/pad_digest_utility.c

Index: utility/pad_digest_utility.c
diff --git a/utility/pad_digest_utility.c b/utility/pad_digest_utility.c
new file mode 100644
index 0000000000000000000000000000000000000000..50f81461577f1be2083afbb3653ca8cb17eade6a
--- /dev/null
+++ b/utility/pad_digest_utility.c
@@ -0,0 +1,54 @@
+/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Utility for to generate a padded hash suitable for generating
+ * PKCS#1.5 signatures.
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "file_keys.h"
+#include "padding.h"
+#include "signature_digest.h"
+#include "utility.h"
+
+int main(int argc, char* argv[]) {
+  int algorithm = -1;
+  int error_code = 0;
+  uint8_t* digest = NULL;
+  uint8_t* padded_digest = NULL;
+  uint64_t len;
+  uint32_t padded_digest_len;
+
+  if (argc != 3) {
+    fprintf(stderr, "Usage: %s <alg_id> <digest_file>", argv[0]);
+    return -1;
+  }
+  algorithm = atoi(argv[1]);
+  if (algorithm < 0 || algorithm >= kNumAlgorithms) {
+    fprintf(stderr, "Invalid Algorithm!\n");
+    return -1;
+  }
+
+  digest = BufferFromFile(argv[2], &len);
+  if (!digest) {
+    fprintf(stderr, "Could not read file: %s\n", argv[2]);
+    return -1;
+  }
+
+  padded_digest = PrependDigestInfo(algorithm, digest);
+  padded_digest_len = (hash_size_map[algorithm] +
+                       digestinfo_size_map[algorithm]);
+
+  if (!padded_digest)
+    error_code = -1;
+  if(padded_digest &&
+     1 != fwrite(padded_digest, padded_digest_len, 1, stdout))
+    error_code = -1;
+  Free(padded_digest);
+  Free(digest);
+  return error_code;
+}