Vutshi wrote:The cryptography with open key will simply be useless with appearance of quantum computers.
Not quite so. There are public key crypto schemes (error correction codes-based McEliece cryptosystem for example) which are resistant to QC algorithms, but not used at the moment due to exceedingly large keys or other factors.
Vutshi wrote:However, there is quantum cryptography. ... It provides absolutely secure secret key distribution which is later used to encode a message.
...with classic crypto algorithms. The real problem with so called quantum crypto (which actually is quantum key distribution) is that it requires dedicated physical end-to-end channels. So QKD is as much
I don't say it isn't worth to research that field (in fact i have a couple of friends with PhD in quantum physics who work on quantum channels and QKD, and it's quite fascinating to listen to them), but all the hype around this topic created by commercial vendors is sometimes very frustrating.