Add a rand_util method for generating a random string.

We need this function to generate a nonce for MAC cookies.

Review URL: http://codereview.chromium.org/6904118

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@83588 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 16 insertions, 0 deletions

diff --git a/base/rand_util.cc b/base/rand_util.cc
index ea6ffd3..d89f8b7 100644
--- a/base/rand_util.cc
+++ b/base/rand_util.cc
@@ -41,4 +41,20 @@ uint64 RandGenerator(uint64 max) {
   return base::RandUint64() % max;
 }
 
+std::string RandBytesAsString(size_t length) {
+  const size_t kBitsPerChar = 8;
+  const int kCharsPerInt64 = sizeof(uint64)/sizeof(char);
+
+  std::string result(length, '\0');
+  uint64 entropy = 0;
+  for (size_t i = 0; i < result.size(); ++i) {
+    if (i % kCharsPerInt64 == 0)
+      entropy = RandUint64();
+    result[i] = static_cast<char>(entropy);
+    entropy >>= kBitsPerChar;
+  }
+
+  return result;
+}
+
 }  // namespace base