---------- Forwarded message ---------- Date: Sun, 14 Jul 2002 15:24:48 +0200 From: Amir Herzberg <amir@herzberg.name> To: cryptography@wasabisystems.com Subject: Fwd: Re: Quantum Computing Puts Encrypted Messages at Risk
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. --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to majordomo@wasabisystems.com