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- Problems with DES Encryption
- by Ratsnatcher
-
- ..........................................................................
-
- *** Quoting M. Stirner to All ***
-
- > The Gov't. standard encryption scheme was proven breakable
- > before official adoption. A guy @ Stanford busted it &
- > suggested that substitution of a 64-bit scheme would make it
- > actually unbreakable. The NSA objected to that much
- > security. Indeed, it is my understanding that pending
- > Federal legislation will make it illegal to transmit
- > encrypted data without a "backdoor." It is widely believed
- > that the NSA currently has "backdoor" ability for the current
- > Gov't. encryption standard. . ~ . M.
-
- Yeah... Scary stuff, yeah. Well here's what my Tanenbaum Textbook on Computer
- Networks says about the DES--which is what I think you're talking about.
-
- ..........................................................................
-
- The DES Controversy
-
- Before leaving the subject of DES, it is worthwhile pointing out
- that this cipher has been surrounded by controversy since its inception
- (Branstad, 1979; et al., 1977; Davida, 1979; Diffie and Hellmen, 1976b, 1977;
- [bunch of other refs...]. A number of computer scientists have made the claim
- that 56 bits is too small a key size, that is, the cipher is too vulnerable to
- attacks such as Hellman's. The key size, in IBM's original design was 128
- bits, which unquestionably eliminates any chance of an exaustive search of the
- key space. At the request of the U.S. National Security Agency, the key size
- was reduced to 56 bits. The reason the cipher was weakened has not been made
- public.
-
- What has also bothered a number of scientists is IBM's refusal to
- make public the reasons the specific S-boxes in the cipher were chosen. IBM
- has said that the National Security Agency requested that it keep the design
- principles secret. Without knowing the design principles, it is difficult to
- exclude the possibility that a trick exists by which the cipher can be easily
- broken. There was also an incident that some observers interpreted as an
- attempt by a government employee to stifle publication of academic research
- aimed at developing stronger ciphers (Shapley and Kolata, [bunch of other
- refs...]).
-
- The net effect of a short key, secret design principles, and other
- factors has led some critics (e.g., Hellmen [more refs...]) to believe that
- the government might not be unhappy with a standard cipher just strong enough
- to keep everyone except itself from breaking it. To understand the
- significance of these developments, you should realize that in the future,
- telephones may contain microcomputers capable of digitizing and encrypting
- speech, and mail may be send electronically, from home terminal to home
- terminal. If unbreakable encryption algorithms were used in these
- applications, it would be impossible for governments to tap phone and
- surreptitiously read mail. As Kahn (1980) and [blaw blaw blaw...] point out,
- electronic eavesdropping is currently practiced on a large scale, so technical
- advances making it impossible in the future may not be viewed with great joy
- in all quarters.
- -- Computer Networks
- Network Security and Privacy
- Andrew S. Tanenbaum
- ..........................................................................
-
- Then he goes on to talk about other problems with DES, like distribution of
- keys and more [blaw blaw blaw]. It gets extremely technical.
-
- Scary stuff though... Another very interesting book about this kind of
- stuff--scary stuff--is "The Rise of the Computer State" by David Burnham,
- which is mostly about the uses of the NSA, CIAs, and FBIs computer resources.
- Come to think of it, that's one of the scariest books I've ever read...
-
- Spock protect us all!
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