Yahoo finally enables HTTPS encryption for email by default

Yahoo finally enables HTTPS encryption for email by default

Summary: Yahoo webmail users will get a significant security benefit with the company enabling encryption by default, but a security expert questions where is Yahoo's "perfect forward secrecy"?


From today, Yahoo will begin encrypting all email connections by default, offering its users the same additional security that Google rolled out for Gmail in 2010.

Yahoo has now enabled Secure Sockets Layer (SSL) — denoted by 'HTTPS' in browsers' URL bar — encryption by default for its roughly 200 million Yahoo Mail users, meeting the 8 January deadline it announced last October.

The change means that Yahoo Mail users no longer need to manually configure their accounts to enable SSL encryption for mail, which encrypts communications between the browser and Yahoo's web servers and is meant to ensure to the user the site they're communicating with really is what it claims to be.

"Anytime you use Yahoo Mail — whether it's on the web, mobile web, mobile apps, or via IMAP, POP or SMTP — it is 100 percent encrypted by default and protected with 2,048 bit certificates," Jeff Bonforte, Yahoo SVP of communication products, wrote in a company blog post.

While HTTPS by default is good news for Yahoo users, it's far less secure than earlier HTTPS implementations by Facebook, Twitter and Google, according to Tod Beardsley, metasploit engineering manager at Boston-based security firm Rapid7. 

"Yahoo's announcement that it has enabled HTTPS encryption for all Yahoo Mail users is not only too little too late, but also quite troubling. It appears that Yahoo is not supporting PFS (Perfect Forward Secrecy)," Beardsley told ZDNet. 

PFS would prevent what's known as "retrospective decryption", where an attacker has captured encrypted sessions today, but doesn't immediately have the private key to unseal it. If in the future the attacker does acquire the private key — say by hacking Yahoo's servers, or through a court order — they can decrypt the captured session. 

The temporary nature of the keys that are generated under PFS also make it a bigger hassle for an attacker if they do manage to capture the key, according to Beardsley. 

"With PFS, another encrypted session happens before the HTTPS session starts, using temporary keys that aren't used for anything else. Even if an attacker got a hold of that temporary key, it's only good for that session and that session only. They'd have to recover a new, unique key for every session they decrypt."

Google, Facebook, and Twitter on the other hand employ Elliptical Curve Diffie-Hellman Exchange, where they can generate a one-time key.

"I can't think of a legitimate reason to prefer this weaker encryption strategy," he said of Yahoo's implementation. 

Google enabled SSL by default for Gmail in 2010, SSL by default in search (for signed-in users) in 2011 and now makes all searches SSL by default. Also, in November it completed its upgrade of all SSL certificates to 2048-bit RSA, with the longer key lengths making it harder to crack SSL connections.

Yahoo's plans to encrypt mail by default came after the first leaks from Edward Snowden, revealing the US National Security Agency (NSA) spy programs that targeted major US internet companies.

The NSA has also prompted a bigger response from Yahoo, which since pledged to encrypt all data moving from the internet to its servers and all data moving between its datacentres, with the latter being a response to revelations of the NSA's 'Muscular' program, which exploited unencrypted links between datacentres of Yahoo and Google.

Topics: Security, Google, Microsoft

Liam Tung

About Liam Tung

Liam Tung is an Australian business technology journalist living a few too many Swedish miles north of Stockholm for his liking. He gained a bachelors degree in economics and arts (cultural studies) at Sydney's Macquarie University, but hacked (without Norse or malicious code for that matter) his way into a career as an enterprise tech, security and telecommunications journalist with ZDNet Australia. These days Liam is a full time freelance technology journalist who writes for several publications.

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  • Important distinction - Yahoo is _not_ encrypting email

    One subtle, yet important distinction needs to be made here. Yahoo is only encrypting the _browser session_ as a user manages folders or composes an email. The email itself is sent in the clear across the internet and is _not_ encrypted.

    This announcement makes for nice PR buzz in the wake of the NSA revelations, but the underlying change does nothing to protect email messages being sent or received by Yahoo Mail users.
    Pete Cafarchio
    • Really?

      Are you sure? Can you provide a source? Because I always thought HTTPS encryption begins with user machine, covers transmission all the way, and the info (e.g. email message) is decrypted at the recipient end.
      • Clarification

        By recipient, I meant Yahoo servers, not the email addressee.
    • Important distinction, glad you pointed this out

      Kind of a funny thing really because people assume this means fully encrypted communication from the writer to the reader.

      In reality, your session to edit the email is encrypted. The little lock on your browser tells you so. But then you hit send and the magic begins ...

      Like a typical email server, Yahoo is going to be transmitting email in unencrypted format across the web to unknown servers anywhere. Heck your email could end up going through a server in my basement (I'm watching .... okay maybe not). Not a Yahoo thing in particular, just how email works.

      I think where this is headed is they'll encrypt data on their servers and then they'll provide end to end encryption support for any users --- inside their email ecosystem first, since they can control that. All the big providers will probably do that and toute as a feature.

      So we'll see a future soon where Yahoo and Googke, etc... talk about secure email from any of their users to any of their users. Who knows, then maybe partnerships will secure intra-site pipes but that would require collaboration that I doubt would happen.
  • Late to the party

    But at least you showed up.
  • How about hotmail / live mail?

    How about Live mail, aka hotmail form MS. Are they encrypted?
    • real encryption must be sender to recipient

      My personal favorite is CryptoHeaven http:\\ it is running since 2001 and is the codebase for SaluSafe http:\\salusafe.comCheckout the source code on GitHub. The source code was recently posted on GitHub, but apparently it was always available on company’s website.
  • Yahoo

    This company is sooooooo 20th century!
  • Yahoo

    LOL......Google has been leading Yahoo around by the nose for the last three years!