[there were 3 possible solutions to this challenge, with 3 available flags]

We have new signature requirements from Central Licensing.
We're happy to comply, but,...it's a bit slow. Can you figure it out?
Service: [not currently available online] Reference Client: https://github.com/openctf/openctf-2015-dc23/blob/master/challange_downloads/sign_faster_client-d57fe60ab04625921121656d3695beca?raw=true