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Re: Quantum cryptography
On Fri, 28 Jan 1994, Yaroslav Faybishenko wrote:
> i assume the message would be translated in blocks (instead of in a
> stream), and then those blocks would be compared to verify that no one
> is eavesdropping. So, if there is actually someone eavesdropping, then
> the very first block that is transmitted would be corrupt, so when Alice
> and Bob compare their versions of the block, they would discover that
> the channel is insecure, so they would stop the conversation.
I believe here you are kind of describing the private channel
(the quantum channel) though I've never heard of it described in quite
this way. When I refer to the Public Channel, I am referring to the
channel that Alice and Bob talk on so that they may compare the blocks or
bits that they have both received. Hence, a powerful enough Eve could
insert herself in the private channel (this is very much discussed) as
well as the public channel (which I haven't seen addressed.)
Many of the papers discuss Eve inserting herself in the
private channel and impersonating Alice (to Bob), and Bob (to Alice),
but this results in a non-correlation of the measurements when compared
over the public channel.
But if Eve may impersonate both people on _both_ channels it may
be possible to dupe Alice and Bob. I expect what is important is the
definition of what a public channel is? (Still haven't got access to my
original thoughts on this, will say more later.)
Regards,
Joseph M. Reagle Jr. |
[email protected] | It is a good day to die! --Worf.
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