in WinRAR: Advanced → Compression → Solid block size → Choose 128MB–1GB depending on RAM.
RAR supports AES-256 encryption (since version 5.0). Earlier versions used weaker AES-128. hrj01217518rar better
Even a “better” compressed archive is useless if it’s silently corrupted. Always: in WinRAR: Advanced → Compression → Solid block
One of RAR’s unique advantages is the (% of archive size reserved for repair data). No other mainstream format does this as efficiently. hrj01217518rar better
: Only download extraction software from official sites like those linked above to avoid malware. Check File Integrity
: If this string is encrypted or encoded, specify the method used for encryption so someone can help you decode it.