'Right now, two keys are required, and those keys are not accessible by the same people,' Perry wrote in a Q&A near the end of the post. Two cryptographic keys would be required for a tampered version of the Tor Browser to be distributed without at least initially tripping security checks: the SSL/TLS key that secures the connection between a user and Tor Project servers plus the key used to sign a software update. 'Even if a government or a criminal obtains our cryptographic keys, our distributed network and its users would be able to detect this fact and report it to us as a security issue,' Perry wrote. 'From an engineering perspective, our code review and open source development processes make it likely that such a backdoor would be quickly discovered.'

Over the last few years, Tor has concentrated on enabling users to take its source code and create their 'deterministic builds' of Tor that can be verified using the organization's public cryptographic keys and other public copies of the application.

Tor project hopes code with