To meet national export limitation in many countries, RC4 often uses a key length of ________ bits.

• A. 8
• B. 40
• C. 100
• D. 256

Answer: (B)

Export restrictions historically limited how large cryptographic keys could be when software was exported. RC4 is flexible and can operate with a range of key lengths, so vendors created export-grade versions that used a deliberately short key to stay compliant while still providing encryption. That approach is why a small key length is associated with RC4 in those contexts—the goal was regulatory compatibility, not modern security strength. The other lengths described would either be far too small to matter in practice or far larger than what those export rules allowed, and today we use much longer, stronger keys.