Fwd: Re: Quantum Computing Puts Encrypted Messages at Risk

[Amir Herzberg]

>At 20:50 11/07/2002, Ian wrote:
>>When I first read The Code Book (Simon Singh), I drooled endlessly at
>>the idea of Unbreakable Encryption, until I became a little more
>>cynical. I questioned Dr Singh on this when he came and gave a lecture
>>in Cheltenham UK recently, and his best answer was that QKD is so secure
>>because "its a different kind of system. Its not like conventional
>>encryption." [synopsis - not direct quotation]. I'm not thorougly
>>convinced.
>>
>>Can anyone (politely) prove this mere outsider wrong?
>
>I am also not a physicist. So I share your skepticism about relying for 
>security on physic theories which I don't understand, and furthermore 
>which may evolve and refine over time.
>
>However, as many people are excited about Quantum crypto, I really would 
>like to put my skepticism aside and understand what is its cryptographic 
>significance, say if we accept the physics as valid (for ever or at least 
>`long enough`). In particular I'm considering whether I should and can 
>cover this area in my book. I must admit I haven't yet studied this area 
>carefully, so my questions may be naive, if so please excuse me (and your 
>answer will be doubly appreciated). Some questions:
>
>1. Quantum key encryption seems to require huge amounts of truly random 
>bits at both sender and receiver. This seems impractical as (almost) truly 
>random bits are hard to produce (especially at high speeds). Is there a fix?
>2. After the transmission, the receiver is supposed to tell the sender how 
>it set its polarization; how is this authenticated? If it isn't we are 
>obviously susceptible to man in the middle attack.
>3. It seems the quantum link must connect directly from sender to 
>receiver. How can this help provide end to end security on the Internet? 
>Or are we back to private networks?
>4. As to quantum computation signalling the end of `crypto as we know 
>it`... Is it fair to say this may end only the mechanisms built on 
>discrete log and/or factoring, but not shared key algorithms like AES and 
>some of the other public key algorithms?
>
>Best, Amir Herzberg

--------------------------------------------------------------------------------------------------------------------------------
Amir Herzberg
See http://amir.herzberg.name/book.html for draft chapters from 
`Introduction to Cryptography,
Secure Communication and Commerce`, and link to lectures. Comments 
appreciated.


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