CDMF

In cryptography, CDMF (Commercial Data Masking Facility) is an algorithm developed at IBM in 1992 to reduce the security strength of the 56-bit DES cipher to that of 40-bit encryption, at the time a requirement of U.S. restrictions on export of cryptography. Rather than a separate cipher from DES, CDMF constitutes a key generation algorithm, called key shortening. It is one of the cryptographic algorithms supported by S-HTTP.

Like DES, CDMF accepts a 64-bit input key, but not all bits are used. The algorithm consists of the following steps:

The resulting 64-bit data is to be used as a DES key. Due to step 3, a brute force attack needs to test only 2⁴⁰ possible keys.

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