For several days , the launcher has been unable to connect to the authentication servers.
I've tried deleting everything starting with a freshly downloaded launcher.
It can connect to other servers and download any files it needs, and I can play offline, if i used a backed up .json file.

Edit: This Create Issue form will not let me select 1.5.3 as the correct launcher version number

Edit:
Reinstalling Java 1.7.0_67 fixed the problem