Twitter is having trouble again with a digital certificate that secures communications to its website, which has been causing trouble for third party applications that integrate with it, but the problem may have been fixed.
Some users have reported trouble in using TweetDeck, an application used to post messages to Twitter and organize other streams of messages from the microblogging service. Users see a message saying that a SSL (Secure Sockets Layer) certificate issued by Equifax to "*.twitter.com" has expired and/or is invalid.
The certificate apparently expired on Monday and was used for api.twitter.com, which is used by third party applications to exchange data with the service. Later in the day on Monday, it appeared the certificate had been renewed, with a new expiry date of August 15, 2011.
SSL is an encrypted protocol used to protect information exchanged between a user and a website. Browsers indicate an SSL connection by displaying a padlock.
Efforts to contact TweetDeck were unsuccessful, but Twitter staff posted on its website that "some users are seeing a sporadic SSL certificate issue in client apps. We're investigating. So many machines." On July 13 Twitter posted on its status blog that "we are aware of an SSL issue on our API and are in the process of fixing it. This issue does not pose a threat to account security."
Twitter apparently knew that the certificate was close to expiring. John Adams, an operations engineer for Twitter, wrote in a Google Groups posting in May that they planned to upgrade the certificate use for api.twitter.com.
Twitter also upgraded the certificate for twitter.com to a VeriSign Class 3 EV certificate, Adams wrote. That certificate uses 256-bit AES (Advanced Encryption Standard) encryption to protect communications.