1 files changed, 48 insertions, 0 deletions
diff --git a/util/crypto/secure_hash.h b/util/crypto/secure_hash.h
new file mode 100644
index 00000000..7c007f96
--- /dev/null
+++ b/util/crypto/secure_hash.h
@@ -0,0 +1,48 @@
+// Copyright 2019 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.
+
+#ifndef UTIL_CRYPTO_SECURE_HASH_H_
+#define UTIL_CRYPTO_SECURE_HASH_H_
+
+#include <stddef.h>
+
+#include <memory>
+#include <string>
+
+#include "openssl/base.h"
+#include "openssl/evp.h"
+#include "platform/base/macros.h"
+
+namespace openscreen {
+
+// A wrapper to calculate secure hashes incrementally, allowing to
+// be used when the full input is not known in advance. The end result will the
+// same as if we have the full input in advance.
+class SecureHash {
+ public:
+  SecureHash(const EVP_MD* type);
+  SecureHash(const SecureHash& other);
+  SecureHash(SecureHash&& other);
+  SecureHash& operator=(const SecureHash& other);
+  SecureHash& operator=(SecureHash&& other);
+
+  ~SecureHash();
+
+  void Update(const uint8_t* input, size_t len);
+  void Finish(uint8_t* output);
+
+  // Handy versions that do the kludgy casting to unsigned in the background.
+  void Update(const std::string& input);
+  void Finish(char* output);
+
+  size_t GetHashLength() const;
+
+ private:
+  bssl::UniquePtr<EVP_MD_CTX> ctx_ =
+      bssl::UniquePtr<EVP_MD_CTX>(EVP_MD_CTX_new());
+};
+
+}  // namespace openscreen
+
+#endif  // UTIL_CRYPTO_SECURE_HASH_H_