About Twofish Encryption
Twofish is a symmetric key block cipher designed by Bruce Schneier and a team of cryptographers
as a successor to Blowfish. It was one of the five finalists in the Advanced Encryption Standard
(AES) competition, though it was not selected as the final standard.
- Twofish has a block size of 128 bits and key sizes up to 256 bits.
- It is a 16-round Feistel network with a bijective F function.
- The cipher incorporates key-dependent S-boxes, a relatively complex key schedule, and a
highly nonlinear maximum distance separable matrix.
- Twofish is unpatented and has been placed in the public domain.
Key Features:
- Security: Twofish has been extensively analyzed and no practical
cryptanalytic attacks against it have been found.
- Performance: It was designed to be efficient on a wide range of platforms
and is particularly fast in software implementations.
- Flexibility: Twofish supports key sizes of 128, 192, and 256 bits, making
it adaptable to different security requirements.
- Key-dependent S-boxes: Unlike many other block ciphers, Twofish uses
S-boxes that are derived from the encryption key, adding an extra layer of security.
Comparison with AES:
While AES (Rijndael) was ultimately selected as the standard, Twofish remains a strong
alternative:
- Twofish is generally slightly slower than AES in software but can be faster in certain
hardware implementations.
- Twofish's key setup is more complex than AES, which can be a disadvantage for applications
that frequently change keys.
- Both algorithms are considered secure against known attacks, with no practical
vulnerabilities discovered.