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| | The IBM Key Management Scheme for DES |
 | | Having the terminal keys on the host system, enciphered under its master key, means that someone could intercept the session key in transmission, find the encrypted terminal master key in storage, and use it to decrypt the session key. |
 | | Initially, to create the copies of the terminal master key enciphered under the auxilliary key, one can use a copy of KM1 enciphered with itself as the first input to an RFMK instruction; as the second input, a copy of the terminal master key, encrypted under KM0 as produced by the EMK instruction is used. |
 | | But using such an instruction for communications security would allow people to take an intercepted session key (enciphered under the terminal master key, from a transmission) and make it more useful, by converting it to a form enciphered under the host master key, with which the DCPH instruction allows them to decode the transmission. |
| www.quadibloc.com /crypto/mi060701.htm (1653 words) |
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