Papers about "Algorithm hiding" ?

[Jerrold Leichter]

| Hi,
| 
| you most probably have heard about the court case where the presence
| of encryption software on a computer was viewed as evidence of
| criminal intent.
| 
| http://www.lawlibrary.state.mn.us/archive/ctappub/0505/opa040381-0503.htm
| http://news.com.com/Minnesota+court+takes+dim+view+of+encryption/2100-1030_3-5718978.html
| 
| 
| 
| Plenty of research has been done about information hiding.
| But this special court case requires "algorithm hiding" as a kind of
| response. Do you know where to look for papers about this subject?
There was a paper published on this a while back.  The question was posed as 
essentially:  Can one produce a "one-way trapdoor compiler"?  That is, just as 
an encryption algorithm takes plaintext and converts it to cryptotext, with 
the property that the inverse transformation is computationally intractable 
without the key, we want something that takes an algorithm and a key and 
produces a different but equivalent algorithm, such that asking some set of 
questions (like, perhaps, whether the output really *is* equivalent to the 
input) without the key is computationally intractable.  The result of the 
paper was that no such compiler can exist.
 
| What about designing an algorithm good for encryption which someone
| can not prove to be an encryption algorithm?
Can prove *any* algorithm is an "encryption algorithm"?  If so, I think there 
are some big prizes coming your way.

On a more general note:  This court case is being blown out of proportion. 
Screwdrivers, hammers, and a variety of other implements are "burglar's 
tools".  If you are caught in certain circumstances carrying burglar's tools, 
not only will they be introduced into evidence against you, but the fact you 
have them will be a criminal violation in and of itself.  The way the law 
deals with all kinds of ambiguities like this is to look at intent:  If I 
carry a screwdriver to repair a broken door on my own house, it's not a 
burglar's tool.  If I carry it to break the lock on my neighbor's house, it 
is.  Determining intent is up to a jury (or judge or judge's panel, depending 
on the legal system and the defendent's choices).  It's outside the realm of 
mathematics, proof in the mathematical sense, or much other than human 
judgement.  If an expert witness testifies something is an encryption 
algorithm, and the jury believes him more than the defense's expert witness 
who testifies it's a digital controller for a secret ice cream maker ... 
that's what it is.  If the jury further believes that encryption algorithm was 
used in the furtherance of a crime ... the defendent is in trouble.

							-- Jerry


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