From: Zhahai.Stewart@f93.n104.z1.fidonet.org (Zhahai Stewart)
Newsgroups: comp.org.eff.talk
Subject: Re: Registering "Assault Keys"
Date: Sun, 08 Nov 92 16:26:48 PDT
Organization: FidoNet node 1:104/93 - Adelante, Boulder CO

 DS> Zhahai Stewart says the government's objective is to have keys just
 DS> strong enough to protect commercial communications but not strong
 DS> enough to resist the NSA.

 Not quite.  I would say "encryption systems", and by that I refer to a
 combination of algorithms and allowed/utilized key length.  For example,
 the NSA apparently trimmed the DES keylength down to 56 bits from an
 originally higher number.  They also allow export of RSA based software
 only if it limits the key length below certain numbers of bits, I hear.

 DS> I'm puzzled. Can I infer that he is explaining registration of public
 DS> key system private keys as a consistent with the above? 

 No, separate thread.  I was responding to a question regarding "why
 doesn't the government allow commercial encryption to make industrial
 espionage (especially from other countries) harder"?  My answer was that
 the gov't does encourage corporate encryption, secure enough but not too
 secure.

 DS> If so, there
 DS> seems to be a logical flaw in the argumentation. A system which uses
 DS> public keys for transmitting random keys used to encrypt the attached
 DS> message via, say, DES, is no stronger cryptologically than DES with a
 DS> different key each time. Yet there has been no request by the
 DS> government that DES keys be deposited, nor a requirement (which would
 DS> be silly) that DES users always use the same key. 

 Allow me to address this for a moment.  First, as Dorothy Denning has
 stated, the federal government has not proposed depositing private keys,
 at least not yet.  So far that is a proposal by private parties, in an
 earnest attempt to provide a workable compromise (incidentally, if you
 have been following my writings, I oppose the suggestion).

 So far, the fragmentary proposal from Denning, et al, has not gone into
 any great detail about what sort of single-key encryption algorithm or
 keys would be allowed (bootstrapped via a random key in a public key
 encrypted header).  PGP 2.0 (Pretty Good Privacy) actually uses IDEA
 currently, rather than DES.  There are proposals to use triple-DES,
 with 64 bit initialization vectors; or to use some form of DES + IDEA.
 (PGP 1.0 used an idiosyncratic single key encryption method which had
 the disadvantage of never having been well scrutinized crytographically;
 this scheme could be resurrected in combination with DES and/or IDEA.) 
 This will continue to evolve.  Absent any regulation, the single key
 encryption cannot be guaranteed crackable by the government.  And even
 DES may not yet be cheap to crack.  So Denning's proposal would allow
 the gov't relatively cheap and guaranteed access to publicly transmitted
 encrypted data, protected (in theory) by court orders.  Note that not
 only the NSA, but the local police department, would have access to this
 sort of cracking (and probably unauthorized others, but that's another 
 matter).

 Not all uses of "law enforcement" or "the government" are identical.
 Not all single key systems will be pragmatically crackable.  And the
 cost of doing so is something that the government would like to avoid.
 I hope this resolves any apparent "logic" problems you had with my post.
    ~z~


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