DiscIO: Implement re-encryption of Wii partition data

Source/Core/DiscIO/WiiEncryptionCache.h

@@ -0,0 +1,47 @@
+// Copyright 2020 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+#include <limits>
+#include <memory>
+
+#include "Common/CommonTypes.h"
+#include "DiscIO/VolumeWii.h"
+
+namespace DiscIO
+{
+class BlobReader;
+
+class WiiEncryptionCache
+{
+public:
+  using Key = std::array<u8, VolumeWii::AES_KEY_SIZE>;
+
+  // The blob pointer is kept around for the lifetime of this object.
+  explicit WiiEncryptionCache(BlobReader* blob);
+  ~WiiEncryptionCache();
+
+  // Encrypts exactly one group.
+  // If the returned pointer is nullptr, reading from the blob failed.
+  // If the returned pointer is not nullptr, it is guaranteed to be valid until
+  // the next call of this function or the destruction of this object.
+  const std::array<u8, VolumeWii::GROUP_TOTAL_SIZE>* EncryptGroup(u64 offset,
+                                                                  u64 partition_data_offset,
+                                                                  u64 partition_data_decrypted_size,
+                                                                  const Key& key);
+
+  // Encrypts a variable number of groups, as determined by the offset and size parameters.
+  // Supports reading groups partially.
+  bool EncryptGroups(u64 offset, u64 size, u8* out_ptr, u64 partition_data_offset,
+                     u64 partition_data_decrypted_size, const Key& key);
+
+private:
+  BlobReader* m_blob;
+  std::unique_ptr<std::array<u8, VolumeWii::GROUP_TOTAL_SIZE>> m_cache;
+  u64 m_cached_offset = std::numeric_limits<u64>::max();
+};
+
+}  // namespace DiscIO