[14190] in cryptography@c2.net mail archive

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Re: quantum hype

daemon@ATHENA.MIT.EDU (Hadmut Danisch)
Tue Sep 16 16:10:49 2003

X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
Date: Tue, 16 Sep 2003 22:03:13 +0200
To: David Wagner <daw@cs.berkeley.edu>
Cc: cryptography@metzdowd.com
In-Reply-To: <bk00tg$49h$1@abraham.cs.berkeley.edu>
From: hadmut@danisch.de (Hadmut Danisch)

On Sat, Sep 13, 2003 at 09:06:56PM +0000, David Wagner wrote:
> 
> You're absolutely right.  Quantum cryptography *assumes* that you
> have an authentic, untamperable channel between sender and receiver.

So as a result, Quantum cryptography depends on the known 
methods to provide authenticity and integrity. Thus it can not 
be any stronger than the known methods. Since the known methods
are basically the same a for confidentiality (DLP, Factoring), 
and authentic channels can be turned into confidential channels
by the same methods (e.g. DH), Quantum cryptography can not be
stronger than known methods, I guess.

On the other hand, quantum cryptography is based on several 
assumptions. Is there any proof that the polarisation of a 
photon can be read only once and only if you know how to turn 
your detector? 

AFAIK quantum cryptography completey lacks the binding to 
an identity of the receiver. Even if it is true that just a single
receiver can read the information, it is still unknown, _who_
it is. All you know is that you send information which can be read
by a single receiver only. And you hope that this receiver was the
good guy.

Hadmut

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