Admin: Created page with "In cryptography, '''CDMF''' ('''Commercial Data Masking Facility''') is an algorithm developed at IBM in 1992 to reduce the security strength of the 56-bit encryptio..."

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Created page with "In cryptography, '''CDMF''' ('''Commercial Data Masking Facility''') is an algorithm developed at IBM in 1992 to reduce the security strength of the 56-bit encryptio..."

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In [[cryptography]], '''CDMF''' ('''Commercial Data Masking Facility''') is an algorithm developed at [[IBM]] in 1992 to reduce the security strength of the [[56-bit encryption|56-bit]] [[Data Encryption Standard|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]].

==Algorithm==
Like DES, CDMF accepts a 64-bit input [[key (cryptography)|key]], but not all bits are used.
The algorithm consists of the following steps:

#Clear bits 8, 16, 24, 32, 40, 48, 56, 64 (ignoring these bits as DES does).
#[[XOR]] the result with its encryption under DES using the key 0xC408B0540BA1E0AE.
#Clear bits 1, 2, 3, 4, 8, 16, 17, 18, 19, 20, 24, 32, 33, 34, 35, 36, 40, 48, 49, 50, 51, 52, 56, 64.
#Encrypt the result under DES using the key 0xEF2C041CE6382FE6.

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 2<sup>40</sup> possible keys.

==Source==

[http://wikipedia.org/ http://wikipedia.org/]
[[Category:Cryptography]]
[[Category:Cryptographic algorithms]]

CDMF - Revision history

Admin: Created page with "In cryptography, '''CDMF''' ('''Commercial Data Masking Facility''') is an algorithm developed at IBM in 1992 to reduce the security strength of the 56-bit encryptio..."