From: IN%"jamesd@echeque.com" 5-MAY-1996 14:18:14.34

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From: Lucky Green

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It is true that the issuer is unable to discover that double blinding is being used. The real problem with the protocol is that it requires payor/payee collusion, which may make it difficult to execute.

At 07:58 PM 5/4/96 EDT, E. ALLEN SMITH wrote:

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Can the payee discover that the payor isn't colluding before the bank can figure out who the payee is?

If the payor is not colluding, then the payee will immediately discover he has not been paid, because the checksums are wrong, and his software says "bad payment"

If the payor is colluding, then no matter what he reveals to the bank, the bank cannot discover the payee. Note that with payee anonymity, the payee does not have to promptly check in his money, so the bank has no hope of narrowing the search by coincidence in time.

But if the payee is colluding, then the payor can be detected by coincidence in time.

The other messages on this appear to be saying about the same thing, with the exception of this last part. _Except_ for that, the payor/payee collusion part doesn't appear to be a problem on the anonymnity side of things. I would guess that Lucky Green's comment was then that there was an additional complexity for payor and payee. -Allen