Switch from keyczar to cryptography library for cryptographic operations (Python 3 support) #3974
Description
Right now we use python-keyczar library for cryptographic operations.
The problem is that the library doesn't support Python 3. There is some unofficial fork / version on PyPi with Python 3 support, but since this is a library which handles critical and sensitive cryptographic operations it would be very irresponsible to just use some "random" non-audited fork.