Tamperproof devices and backdoors

[dmolnar]

On Fri, 25 May 2001, Enzo Michelangeli wrote:

> On the Other Other Hand, I vaguely remember a neat paper by Matt Blaze
> some years ago that shows that certain classes of back doors, like
> "good" back doors in conventional crypto systems, are equivalent in
> difficulty to building a public key system. Anyone remember the name
> of the paper and the exact content?

Skimming the papers on his web page, I would guess it's related to

M. Blaze, J. Feigenbaum and F.T. Leighton, "Master-Key Cryptosytems."
Abstract presented at Crypto '95 (rump session), Santa Barbara, CA, August
1995

http://www.crypto.com/papers/mkcs.ps

which opens by defining a "Master-Key Cryptosystem" and then goes on to
show that a MKCS implies a PKCS. The public key is the cryptosystem with a
back door. The private key is the back door/master key.

-David




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