Lucifer (cryptography)

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developer IBM ( Horst Feistel )
Released 1971
Key length 48, 64 or 128 bit
Block size 48, 32 or 128 bit
structure Substitution-permutation network / Feistel cipher
Round 16 rounds

Lucifer is the name of several block ciphers developed by IBM that were intended for civil use. One of them is the predecessor of DES .

The name is based on the mythological figure Lucifer and is an allusion to demon ( demon ); this in turn was the abbreviation of "demonstration", the name of a system on which Feistel worked. The operating system he was using did not allow filenames of this length.


Lucifer was largely developed by Horst Feistel and his colleagues at IBM. Block ciphers with a similar structure are therefore called Feistel ciphers . In the 1970s , a version of Lucifer was used in electronic banking.

A well-known variant (Feistel, 1973 ) uses a 128- bit key and works with blocks of 128 bit. It is a substitution-permutation network and uses two 4-bit S-boxes . The key selects the S-boxes.

A later version (Sorkin, 1984 ) was a Feistel network in 16 rounds and also works with 128-bit blocks and 128-bit keys.

In 1974, IBM submitted a Feistel network variant as a candidate for the DES tender. After a few modifications (reduction to 56-bit keys and 64-bit blocks, but strengthened against differential cryptanalysis ), the procedure was adopted in 1977 as the Data Encryption Standard .