John works as a professional Ethical Hacker. He has been assigned the project of testing the security of www.we-are-secure.com. He is using a tool to crack the wireless encryption keys. The description of the tool is as follows:
`It is a Linux-based WLAN WEP cracking tool that recovers encryption keys. It operates by passively monitoring transmissions. It uses Ciphertext Only Attack and captures approximately 5 to 10 million packets to decrypt the WEP keys.`
Which of the following tools is John using to crack the wireless encryption keys?