NewDES
In cryptography, NewDES is a symmetric key block cipher. It was created in 1984–1985 by Robert Scott as a potential DES replacement. Despite its name, it is not derived from DES and has a quite different structure. Its intended niche as a DES replacement has now mostly been filled by AES. The algorithm was revised with a modified key schedule in 1996 to counter a related-key vulnerability; this version is sometimes referred to as NewDES-96.
Table of contents |
2 Cryptanalysis of NewDES 3 External links 4 References |
The algorithm
NewDES, unlike DES, has no bit-level permutations, making it easy to implement in software. All operations are performed on whole bytes. It is a product cipher, consisting of 17 rounds performed on a 64-bit data block and makes use of a 120-bit key. In each round, subkey material is XORed with the 1-byte sub-blocks of data, then fed through a round function, the result of which is then XORed with another sub-block of data. In total, 8 XORs are performed in each round. The round function is derived from the United States Declaration of Independence.Each set of two rounds uses seven 1-byte subkeys, which are derived by splitting 56 bits of the key into bytes. The key is then rotated 56 bits for use in the next two rounds.
Cryptanalysis of NewDES
Robert Scott, the designer of NewDES, showed that NewDES exhibits the full avalanche effect after seven rounds: every ciphertext bit depends on every plaintext bit and key bit.NewDES has the same complementation property that DES has: if
Eli Biham's related-key attack can break NewDES with 2^{33} chosen-key chosen plaintexts, meaning that NewDES is not as secure as DES.
John Kelsey, Bruce Schneier and David Wagner used related-key cryptanalysis to develop another attack on NewDES: it requires 2^{32} known plaintexts and one related key. NewDES therefore does not seem very secure: using Triple DES or AES instead would be more prudent.
External links
References
- R. Scott, "Wide Open Encryption Design Offers Flexible Implementations," Cryptologia, v. 9, n. 1, Jan 1985, pp. 75-90.
- John Kelsey, Bruce Schneier, and David Wagner. Related-key cryptanalysis of 3-WAY, Biham-DES, CAST, DES-X, NewDES, RC2, and TEA. Lecture Notes in Computer Science, 1334: pp233–246, 1997.
Block ciphers |
Algorithms: 3-Way | AES | Blowfish | Camellia | CAST-128 | CAST-256 | CMEA | DEAL | DES | DES-X | FEAL | G-DES | GOST | IDEA | Iraqi | KASUMI | KHAZAD | Khufu and Khafre; | LOKI89/91 | LOKI97 | Lucifer | MacGuffin | Madryga | MAGENTA | MARS | MISTY1 | MMB | NewDES | RC2 | RC5 | RC6 | Red Pike; | S-1 | SAFER | Serpent | SHARK | Skipjack | Square | TEA | Triple DES; | Twofish | XTEA |
Design: Feistel network; | Key schedule; | Product cipher; | S-box | SPN Attacks: Brute force; | Linear / Differential cryptanalysis | Mod n; | XSL Standardisation: AES process; | CRYPTREC | NESSIE Misc: Avalanche effect | Block size; | IV | Key size; | Modes of operation; | Piling-up lemma; | Weak key; |