加密加密，能够使用加密数据

Question

I get latitude and longitude from users and store them within a MySQL database. My service seems to be anonymous so I want to encrypt coordinates in an undecryptive way (like md5 does). But the problem is that I need to compute distance in any moment after writing coords to the DB. So, is there any way to make computing operations within that "encrypted dome"? I use PHP. Thanks a lot!

Answer 1

md5 is hashing, not encryption. Therefore you are losing information, that can never be restored again. With lost information you can't do any calculations.

What you need is a true encryption, which then works both ways, to decrypt your data. There is no way around it.