Convergence was a proposed strategy for replacing SSL certificate authorities, first put forth by Moxie Marlinspike in August 2011 while giving a talk titled "SSL and the Future of Authenticity" at the Black Hat security conference.

In the talk, Marlinspike proposed that all of the current problems with the certificate authority (CA) system could be reduced to a single missing property, which he called "trust agility" and which Convergence aimed to provide.

[2][3] As of 2013,[4] Marlinspike was focused on an IETF proposal called TACK,[5] which was designed to be an uncontroversial first step that advocates for dynamic certificate pinning instead of full CA replacement and reduces the number of times a third party needs to be trusted.

[8][independent source needed] Convergence was based on previous work from the Perspectives Project at Carnegie Mellon University.

Web browsers typically include a list of default trusted CAs and display a warning about an "untrusted connection" when a site cannot be vouchsafed by a trusted CA.