On 11/12/2017 10:43 AM, Yuraeitha wrote: >> As for quantum networks, they are slightly more obtainable than, say, >> moon rockets. > > [...] > Given the fiber internet network might be able to carry these signals, it's > not farfetched to imagine we'll start to have portions of Quantum internet in > less than 10 years. It's a cheap technology too. While sure such research > costs a lot to do, the technology itself should be relatively cheap, and a > lot of the quantum computing research costs come from universities whom give > away their research fore free mostly now a days (Open Science movement, kinda > like Open Source movement). > [...]
The issue with all current quantum-physics-based encryption that I know of is that it requires a direct fiber link between the source and the destination. Also, the segment length is currently about ~4-5km if I remember correctly, though it may just as well have changed since a few years ago. But this direct fiber link means quantum-physics-based encryption will never be end-to-end between you and the website you are visiting. And if this quantum-physics-based encryption is terminated by eg. your ISP (the only one you have a physical fiber link to), then your ISP could use the exact same techniques as before to spy on you. Basically, quantum-physics-based encryption is nice in that it is demonstrably secure (modulo Bell's inequalities, last time I checked on this is getting quite old, so I'm not sure about every detail). But its constraints of use are really huge, so it is not likely to ever get in your house unless you're at the head of a billion-dollar-level entity, be it a state or a company. > I've wondered for a good while if splitting up an symmetric encrypted file in > multiple of parts, say for example minimum two parts, and send one over the > internet, and carry the other on yourself in person, that if only one part is > stolen (for example someone steal your laptop with sensitive competitive > business trade secrets), then it's still uncrackable? However it's mostly > been a fun thought experiment, I never managed to confirm it, but I imagine > businesses or even government agencies would want to use such approaches if > its applicable? If it isn't already. Such a scheme is Vernam cipher. It is the only other provably secure cryptographic system that I know of (all the others are based on “we think this problem is hard, so let's prove the cryptosystem is at least as hard as this problem”). Basically to encrypt a N-bit-long message, you generate a N-bit key (with perfect randomness, which is a point where the issue usually lies), you xor it with your message, and to decrypt the message you just xor again the encrypted message with the key. You could then just send the key and the encrypted message through the two means. Funnily enough, Vernam ciphers are actually the basis for quantum-physics-based encryption. The quantum channel is only used to generate the random N-bit key in way so that it is shared by the two protagonists and no eavesdropper could get a reasonable amount of bits without being detected (in which case the transmission can be cancelled without ever using the key) Cheers & hope that helps, Leo -- You received this message because you are subscribed to the Google Groups "qubes-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/qubes-users/966f5e22-8a2c-6386-c2b5-ea2dcafb7eb7%40gaspard.ninja. For more options, visit https://groups.google.com/d/optout.
