Quantum Cryptography

[Greg Rose]

At 10:44  -0700 2007/06/22, Ali, Saqib wrote:
>>...whereas the key distribution systems we have aren't affected by
>>eavesdropping unless the attacker has the ability to perform 2^128 or
>>more operations, which he doesn't.
>
>Paul: Here you are assuming that key exchange has already taken place.
>But key exchange is the toughest part. That is where Quantum Key
>Distribution QKD comes in the picture. Once the keys are exchanged
>using QKD, you have to rely on conventional cryptography to do bulk
>encryption using symmetric crypto.
>
>Using Quantum Crypto to do bulk encryption doesn't make any sense. It
>is only useful in key distribution.

To be used in key distribution I have to have laid a private optical 
fiber between me and my correspondent. I could have paid a lot less 
for an armored truck to carry the key for me. (I know you can do QKD 
without the fiber these days, but how do you know that you agreed the 
key with the person you think you agreed it with? It's turtles all 
the way down.)

Greg.

>
>saqib
>http://www.linkedin.com/in/encryption
>
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