On 8 Jul 99, at 20:37, phoenix@ugcs.caltech.edu wrote:
> hal@finney.org wrote:
>
> > > Question: Does anyone know if there is an encryption
> > > methodology that will work if QC cracks the factoring problem?
>
> There was an article in Science about a month ago reporting what was
> claimed to be a provably secure, and practical (from the POV of likely
> fiber connections and using insecure repeaters) way of exchanging bits
> using quantum computers. I don't have a handy ref, sorry.
>
> -xx- Damien X-)
Is this the same as the idea of passing key data to two receivers by using quantum-coupled photons? The idea is that detecting the spin at one end collapses the spin to be the same at the other end, and any attempt to intercept the bits will be easily detected. However, this would require prearrangement and dedicated lines, so it's no replacement for public key crypto.
It does have the distinction of being the first absolutely secure solution to the problem of distributing one-time pad key material, and therefore to the provably uncrackable cryptosystem problem as well.