Move crypto_helpers from sync to base

crypto/random.cc

Index: crypto/random.cc
diff --git a/crypto/random.cc b/crypto/random.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f06aac393d3bb300e567c3616ce551ffedabe482
--- /dev/null
+++ b/crypto/random.cc
@@ -0,0 +1,30 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "crypto/random.h"
+
+#include <string>
+
+#include "base/base64.h"
+#include "base/rand_util.h"
+
+void GetRandomBytes(char* output, int output_length) {
+  uint64 random_int;
+  const char* random_int_bytes = reinterpret_cast<const char*>(&random_int);
+  int random_int_size = sizeof(random_int);
+  for (int i = 0; i < output_length; i += random_int_size) {
+    random_int = base::RandUint64();

[agl, 2011/04/26 13:59:37]

This is not cryptographically strong on Windows.

+    int copy_count = std::min(output_length - i, random_int_size);
+    memcpy(output + i, random_int_bytes, copy_count);
+  }
+}
+
+std::string Generate128BitRandomHexString() {
+  const int kNumberBytes = 128 / 8;
+  std::string random_bytes(kNumberBytes, ' ');

[agl, 2011/04/26 13:59:37]

no need for a std::string here, a uint8[] will do.

[qsr (NOT THE RIGHT qsr), 2011/04/26 15:24:18]

Except that the base64_encode function expect strings. If I want to use it, I'll
have to create a std::string after.

+  GetRandomBytes(&random_bytes[0], kNumberBytes);
+  std::string base64_encoded_bytes;
+  base::Base64Encode(random_bytes, &base64_encoded_bytes);

[agl, 2011/04/26 13:59:37]

The function name suggests that the data should be hex encoded, not base64.

[qsr (NOT THE RIGHT qsr), 2011/04/26 15:24:18]

As this is a refactoring, I will modify the name of the function, but not what
it does. I will rename the function Generate128BitRandomBase64String

+  return base64_encoded_bytes;
+}