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Re: Selection key crypto protocol trial balloon
Hal <[email protected]>:
> Let me get straight where we are. Rishab's concrete proposal was not an
> implementation, but rather a set of requirements. There was no
> suggestion about any specific algorithms that would meet those
> requirements, right? The question is whether any such algorithm could
> exist.
Right.
> It is hard for me to see how this could possibly work. The message
> receiver sends this "selection key" to the intermediary, and that somehow
> pulls out the saved message, but in a form such that the intermediary
> doesn't recognize it. And the intermediary himself can't tell exactly
> which message is produced. But it is nevertheless exactly the message
> which was meant for this particular receiver.
It need not be the same information - i.e. if the encryption process adds
enough noise to the message, the extraction process might by lossy, without
any total loss for the receiver. This may be possible particularly if
Fourier-style transforms are used, as the "selection key" could pick up
less "frequencies" of a message than are stored at the intermediary.
> The thing is, the receiver does not have much more information than the
> intermediary.
The same could be said of a private/public key pair. What is crucial is the
association between the keys.
This said, while I can imagine separate systems for the intermediary loosing
correlation between incoming and outgoing messages (eg - it's _really_ tough,
without fancy pattern recognition, to associate a JPEG with the original),
and for generating three associated keys (secret splitting? something to do
with Brands' blind signatures?), I really can't imagine a way of putting it
all together. Someone will have to be inspired, as Diffie was...
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