SHA1 certificates for secure SSL/TLS communications are deprecated due to known computational vulnerabilities. To ensure secure communications, a forced deprecation sounds reasonable (i.e. refuse to connect to these). That has the side effect that it will lock out many users who are unable to use stronger hashes such as SHA256. However, if a fallback to SHA1 is provided (as Facebook is proposing), everyone will be vulnerable to SHA1 downgrade man-in-the-middle attacks.
What to do?
(Score: 0) by Anonymous Coward on Friday December 11 2015, @05:12PM
I don't know which versions of web browsers are supported, but the major browsers no longer install on at least old versions of OSX. I still support the forced transition instead of downgrade support.
(Score: 2, Redundant) by pendorbound on Friday December 11 2015, @05:22PM
Current Firefox installs down to SnowLeopard which was released in 2009. The last PPC-based Mac (that can't update to Snowy) was released in 2006.
No question you still have people out there using PPC Mac's, but I think it's time... Maybe someone can backport SHA-256 to Firefox 16.
(Score: 4, Informative) by SomeGuy on Friday December 11 2015, @06:07PM
Already done.
Firefox 38.4.0 ESR for Mac OS 10.4 and 10.5 on Mac PPC: http://www.floodgap.com/software/tenfourfox/ [floodgap.com]