add generic digest class

Change-Id: Ic5d2d8fbb0bb4edc4c966e185be81f6ca673950e
Reviewed-on: https://gerrit.libreoffice.org/36790
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>

include/comphelper/hash.hxx

@@ -0,0 +1,47 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <comphelper/comphelperdllapi.h>
+
+#include <memory>
+#include <vector>
+
+namespace comphelper {
+
+enum class HashType
+{
+    SHA1,
+    SHA256,
+    SHA512
+};
+
+struct HashImpl;
+
+class COMPHELPER_DLLPUBLIC Hash
+{
+private:
+    std::unique_ptr<HashImpl> mpImpl;
+
+public:
+
+    Hash(HashType eType);
+    ~Hash();
+
+    void update(const unsigned char* pInput, size_t length);
+
+    std::vector<unsigned char> finalize();
+
+    static std::vector<unsigned char> calculateHash(const unsigned char* pInput, size_t length, HashType eType);
+
+    size_t getLength() const;
+};
+
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */