Q: Why should we care about this? Why not deal with it when quantum computers finally start cracking existing crypto?
A:
1. It takes time to implement new methods. Would it be acceptable for there to be a period of months or years during which we can't make credit card transactions, etc.?
2. Coded text of messages encoded using conventional cryptographic methods can be intercepted, archived and then broken at a later date. If you make a purchase today, somebody archives the coded exchange, and a quantum computer capable of cracking the encryption used in that exchange becomes available before your credit card expires, you've got a problem. You've got an even bigger problem if you transmit information that remains sensitive for longer than your credit card info.
As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.).
A:
1. It takes time to implement new methods. Would it be acceptable for there to be a period of months or years during which we can't make credit card transactions, etc.?
2. Coded text of messages encoded using conventional cryptographic methods can be intercepted, archived and then broken at a later date. If you make a purchase today, somebody archives the coded exchange, and a quantum computer capable of cracking the encryption used in that exchange becomes available before your credit card expires, you've got a problem. You've got an even bigger problem if you transmit information that remains sensitive for longer than your credit card info.
As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.).