ncch_container: support encrypted games

src/core/file_sys/romfs_reader.cpp

@@ -0,0 +1,22 @@
+#include <algorithm>
+#include <cryptopp/aes.h>
+#include <cryptopp/modes.h>
+#include "core/file_sys/romfs_reader.h"
+
+namespace FileSys {
+
+std::size_t RomFSReader::ReadFile(std::size_t offset, std::size_t length, u8* buffer) {
+    if (length == 0)
+        return 0; // Crypto++ does not like zero size buffer
+    file.Seek(file_offset + offset, SEEK_SET);
+    std::size_t read_length = std::min(length, data_size - offset);
+    read_length = file.ReadBytes(buffer, read_length);
+    if (is_encrypted) {
+        CryptoPP::CTR_Mode<CryptoPP::AES>::Decryption d(key.data(), key.size(), ctr.data());
+        d.Seek(crypto_offset + offset);
+        d.ProcessData(buffer, buffer, read_length);
+    }
+    return read_length;
+}
+
+} // namespace FileSys