Which of the following ciphers would be BEST used to encrypt streaming video?
In cryptography, RC4 is the most widely used software stream cipher and is used in popular Internet protocols
such as Transport Layer Security (TLS). While remarkable for its simplicity and speed in software, RC4 has
weaknesses that argue against its use in new systems. It is especially vulnerable when the beginning of the
output keystream is not discarded, or when nonrandom or related keys are used; some ways of using RC4 can
lead to very insecure protocols such as WEP.
Because RC4 is a stream cipher, it is more malleable than common block ciphers. If not used together with a
strong message authentication code (MAC), then encryption is vulnerable to a bit-flipping attack. The cipher is
also vulnerable to a stream cipher attack if not implemented correctly. Furthermore, inadvertent double
encryption of a message with the same key may accidentally output plaintext rather than ciphertext because the
involutory nature of the XOR function would result in the second operation reversing the first.
It is noteworthy, however, that RC4, being a stream cipher, was for a period of time the only common cipher
that was immune to the 2011 BEAST attack on TLS 1.0. The attack exploits a known weakness in the way
cipher block chaining mode is used with all of the other ciphers supported by TLS 1.0, which are all block