3.4 OTHER CIPHERS

EXERCISE 3.4: OTHER CIPHERS

Do a little research about RC4 and Twofish. Where are they used? What kinds of problems does RC4 have? What are some of Twofish’s advantages over AES?

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Little note on RC4: It is a stream cipher. While it is remarkable for its simplicity and speed in software, multiple vulnerabilities have been discovered in RC4, rendering it insecure. Read more here. RC4 was used in WEP, WPA, SSL, and even TLS until it was prohibited in 2015, by RFC 7465.

Little note on Twofish: Twofish is a symmetric key block cipher with a block size of \(128\) bits and key sizes up to \(256\) bits. Twofish’s distinctive features are the use of pre-computed key-dependent S-boxes, and a relatively complex key schedule.