xts_encryption_layer: Implement XTSEncryptionLayer

src/core/crypto/xts_encryption_layer.h

@@ -0,0 +1,26 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <vector>
+#include "core/crypto/aes_util.h"
+#include "core/crypto/encryption_layer.h"
+#include "core/crypto/key_manager.h"
+
+namespace Core::Crypto {
+
+// Sits on top of a VirtualFile and provides XTS-mode AES decription.
+class XTSEncryptionLayer : public EncryptionLayer {
+public:
+    XTSEncryptionLayer(FileSys::VirtualFile base, Key256 key);
+
+    size_t Read(u8* data, size_t length, size_t offset) const override;
+
+private:
+    // Must be mutable as operations modify cipher contexts.
+    mutable AESCipher<Key256> cipher;
+};
+
+} // namespace Core::Crypto