Ladder-DES
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| Ladder-DES | |
| General | |
|---|---|
| Designers | Terry Ritter |
| First published | February 22, 1994 |
| Derived from | DES |
| Related to | DEAL |
| Cipher detail | |
| Key sizes | 224 bits |
| Block sizes | 128 bits |
| Structure | Nested Feistel network |
| Rounds | 4 |
| Best public cryptanalysis | |
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Eli Biham's attacks require 236 plaintext-ciphertext pairs
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In cryptography, Ladder-DES is a block cipher designed in 1994 by Terry Ritter. It is a 4-round Feistel cipher with a block size of 128 bits, using DES as the round function. It has no actual key schedule, so the total key size is 4×56=224 bits.
In 1997, Eli Biham found two forms of cryptanalysis for Ladder-DES that depend on the birthday paradox; the key is deduced from the presence or absence of collisions, plaintexts that give equal intermediate values in the encryption process. He presented both a chosen-plaintext attack and a known-plaintext attack; each uses about 236 plaintexts and 290 work, but the known-plaintext attack requires much more memory.
[edit] References
- Terry Ritter (February 22, 1994). "Ladder DES". sci.crypt. (Web link). Retrieved on 2007-01-30.
- Eli Biham (1997). "Cryptanalysis of Ladder-DES" (PDF). 4th International Workshop on Fast Software Encryption (FSE '97): pp.134–138, Haifa: Springer-Verlag. Retrieved on 2007-01-30.
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