Which of the following encryption methods will support a key of up to 256-bits?

WPA (Wi-Fi Protected Access) originally used TKIP with RC4-based encryption, not AES with 256-bit keys, though WPA2 later added AES support as a separate option.

AES supports three key lengths - 128, 192, and 256 bits - making it the only choice capable of 256-bit encryption. It is the standard symmetric encryption algorithm adopted by NIST and is used in WPA2/WPA3 wireless security to replace weaker protocols.

TKIP (Temporal Key Integrity Protocol) uses a 128-bit key and was designed as a stopgap replacement for WEP, and does not support 192 or 256-bit key lengths.

WEP (Wired Equivalent Privacy) uses 40-bit or 104-bit RC4 keys, far below 256 bits, and is considered cryptographically broken.