Tumblr now allows users to encrypt their connections with the microblogging service, but the feature is only offered as an option for now.
"You can now take extra precaution against hackers and snoops by enabling SSL security on your Tumblr Dashboard," Conrad Rushing, Tumblr's director of security engineering, said Monday in a blog post. "Just head over to your Account Settings and flip the switch."
The adoption rate of HTTPS -- HTTP with SSL encryption -- by online services has increased rapidly over the past several years, driven in part by significant growth in the mobile market.
Many users today access online services primarily from their smartphones and tablets and these devices are frequently connected to public, insecure and generally untrusted wireless networks. This exposes them to man-in-the-middle attacks where attackers intercept Internet traffic and extract sensitive details from it like session cookies, which then allow them to hijack online accounts.
In addition, documents leaked last year by former U.S. National Security Agency contractor Edward Snowden revealed that intelligence agencies are collecting data about Internet communications from unencrypted traffic as it passes through the global Internet infrastructure. Those revelations have increased awareness about online privacy among users.
The revelations about the NSA's mass data collection programs prompted a commitment from Yahoo to provide users with the option to encrypt their traffic with the company's services by the end of the first quarter of 2014. The company made HTTPS a default setting for its email service at the beginning of January.
Yahoo acquired Tumblr in June 2013, but the company continues to be operated independently.
In a time when many popular online services are rushing to make HTTPS the default setting, or have done so already, Tumblr's decision to offer the feature on an opt-in basis strikes some as a bit unusual.
"The addition of SSL is surely better than plain old HTTP and makes sense especially when the user accesses the service via a mobile application," said Bogdan Botezatu, a senior e-threat analyst at security vendor Bitdefender, Tuesday via email. "However, SSL only makes sense if it is enabled by default, because the regular user won't likely alter the default account settings."
"We will eventually turn on this feature by default for all of our users, but to best handle the immense traffic produced by such an effort, we are beginning first by giving our users the ability to opt-in," said Katherine Barna, Tumblr's head of communications, via email.
"It's understandable why Tumblr decided to gradually roll out SSL to customers, as they probably expect to encounter some technological challenges, but the sooner they transition to SSL, the better for the users," Botezatu said.