David Schwartz wrote:
The crucial part is, that the information of a particle is unrecoverably destroyed if it strikes the wrong detector and there is no other way to get the information from the particle. So you have only one try in decrypting, since afterwards the encrypted message is not there anymore. This beats every cryptanalysis attack, since you do not have anything to analyze...[...]
If an A+ particle strikes an A detector, the detector indicates a +. If an A- particle strikes an A detector, the detector indicates a -. If a B+ particle strikes a B detector, a + is indicated. If a B- particle strikes a B detector, a - is indicated.
The cool part is that if an A+ or A- particle strikes a B detector, the
indication is random, could be + or -. If a B+ or B- particle strikes an A
detector, the indication is random, could be + or -.
[...]
Of course there may be insecure implementations and protocols which would allow other kind of attacks, one of the more obvious problems is the exchange of the shared secret. But the principle of transmitting information this way is IMHO second only to one time pads (which are mathematically proven, whereas there may be physical laws still unknown to us that could allow Mr. Spock to beat quantum physics...).
I would see one not so obvious problem (the same as with one time pads) if the key is reused, since there is no 100% probability of detecting every particle on the receiver's side. So Vladimir could "steal" (and thereby destroy) a small percentage of particles and try his luck in decrypting those. If the key is (very) short in comparison to the number of stolen particles he might guess the key using a known plaintext type of attack.
Can someone confirm or invalidate this idea?
BTW, David's message has been for me the most comprehensible description of quantum encryption I have ever found. I think I finally got it now! ;)
Kind regards Ted ;)
-- PGP Public Key Information Download complete Key from http://www.convey.de/ted/tedkey_convey.asc Key fingerprint = 31B0 E029 BCF9 6605 DAC1 B2E1 0CC8 70F4 7AFB 8D26
smime.p7s
Description: S/MIME Cryptographic Signature
