diff --git a/buffet/privet/openssl_utils.cc b/buffet/privet/openssl_utils.cc
new file mode 100644
index 0000000..17cc16f
--- /dev/null
+++ b/buffet/privet/openssl_utils.cc
@@ -0,0 +1,26 @@
+// Copyright 2014 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.
+
+#include "buffet/privet/openssl_utils.h"
+
+#include <algorithm>
+
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
+
+#include <base/logging.h>
+
+namespace privetd {
+
+chromeos::Blob HmacSha256(const chromeos::SecureBlob& key,
+                          const chromeos::Blob& data) {
+  chromeos::Blob mac(kSha256OutputSize);
+  uint32_t len = 0;
+  CHECK(HMAC(EVP_sha256(), key.data(), key.size(), data.data(),
+             data.size(), mac.data(), &len));
+  CHECK_EQ(len, kSha256OutputSize);
+  return mac;
+}
+
+}  // namespace privetd