Powerful new antiphishing weapon DKIM emerges

DKIM standard attracts Cisco, Google, PayPal and more

DKIM usage booms

DKIM adoption is accelerating, especially among banks, mortgage companies and insurance companies.

"I think there will be rapid adoption of DKIM," says Charles Stiles, director of worldwide business development for Goodmail, a certified e-mail service that will support DKIM in May. "The standard is proving to be very successful. The best and brightest people in the world worked on it. It offers up a foolproof, spoof-proof way to authenticate messages."

BITS, a group of 100 of the largest U.S. financial institutions, last year recommended that its members adopt DKIM by October 2008. BITS also recommended two other standards for securing e-mail: Transport Layer Security (TLS), which encrypts e-mail messages between servers; and either Sender ID Framework (SIDF) or Sender Policy Framework (SPF) to validate that a received e-mail originates from an authorized mail server within a particular domain.

"What BITS is doing here, with all of its members speaking in one voice with such a massive impact, gives people confidence in DKIM," Peterson says. "It's unlike anything we've seen" in terms of driving DKIM adoption.

ISPs are adopting DKIM because they want to protect their customers against spam and phishing scams. E-mail senders are tying to protect their brands, identities and customers from phishing scams.

PayPal and eBay have teamed up with Yahoo to battle phishing attacks with DKIM. PayPal and eBay are signing their e-mails with DKIM, and Yahoo Mail will block e-mails claiming to be sent by eBay and PayPal that haven't been signed through DKIM.

"EBay and PayPal have always attracted fraudsters, phishers and all that. Our customers see too much e-mail that isn't coming from us," says Mike Vergara, director of account protection at PayPal, which is owned by eBay. "DKIM takes a good industrywide standards approach. We need to add strong authentication to our e-mails so customers can have confidence that it did come from us. And we need to get ISPs to leverage that so we can say to them: If it didn't come from us, please don't deliver it."

PayPal is deploying DKIM after already rolling out Sender Policy Framework (SPF), a complementary Microsoft-backed standard that is an extension to the Simple Mail Transfer Protocol (SMTP). SPF allows software to reject e-mail coming out of forged "from" addresses.

Vergara says the hardest part about deploying DKIM was documenting PayPal's e-mail infrastructure to determine all the systems and domains that send e-mail to customers.

"There's no one postmaster at eBay or PayPal. It took a lot of time to figure out all the e-mails we were sending -- transactional e-mails, marketing e-mails, customer support e-mails -- and where they were coming from around the world," Vergara says. "Getting our hands around that took us 12 months. Rolling out e-mail appliances and upgrading them to DKIM took a couple of weeks."

Vergara says DKIM works. He says Yahoo has blocked hundreds of thousands -- sometimes millions -- of messages per day that supposedly came from eBay or PayPal but weren't legitimate because they weren't DKIM signed.

Now PayPal is in discussion with other ISPs to convince them to block messages from either PayPal or eBay that aren't signed with DKIM.

"We can't solve this e-mail fraud problem on our own," Vergara says. "We are trying to light a fire under the ISPs to help us solve this problem for the people who use our services."

DKIM has its limitations. A minority of companies is signing their outbound messages with DKIM, and fewer still are checking for DKIM signatures on inbound mail. But backers of the technology hope this problem will be eliminated as ISPs and banks deploy DKIM.

"If I sign all my messages to protect my brand, but the person receiving it or their ISP aren't checking, it all looks the same to the recipient," Peterson says. "I feel pretty confident that a year from now 30% of all companies will be signing their messages. Yahoo and Gmail have adopted it. Bank of America and PayPal have been very vocal supporters. Hope springs eternal. I do feel that we're at the tipping point for DKIM."

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