Steam and Uplay validate the final Win32 executable ( FarCry4.exe ) using an Authenticode signature and a runtime checksum. Any modification to .dat files triggers a hash mismatch and forces a re-download of the entire archive via differential patching.
This paper focuses on the lifecycle of Far Cry 4 data from download to runtime, examining: far cry 4 data win32 download
The Win32 client splits the 30+ GB download into 1 MB or 4 MB chunks, each SHA-256 hashed. The downloader maintains a local bitmap ( download.bin ) to track completed chunks, allowing resumption after crashes or network failures. This bitmap is stored in %ProgramData%\Ubisoft\DownloadCache for Uplay, or steamapps\downloading\ for Steam. Steam and Uplay validate the final Win32 executable