The Internet Engineering Task Force has published new specifications for authenticating email, another tool in the fight against spam and phishing.
The specifications were published for DomainKeys Identified Mail (DKIM), which combines several existing anti-phishing and anti-spam methods to create an improved way to sort and identify legitimate email. The specifications would allow software vendors and email service providers to build the protections into their products and services immediately.
Instead of using an IP address to identify the sender of each message, DKIM adds a digital signature associated with the sender's domain name. That signature is then validated invisibly at the recipient's end. "White lists" and "black lists" are then used by the email infrastructure software to validate the reputation of the sender.
"Domain names are far more stable than IP addresses," said Dave Crocker, an IT consultant and contributor to the DKIM project. "Domain names align with an organisation far better than an IP address."
Because it incorporates a digital signature, "it allows a piece of email to be identified definitively as somebody's," rather than as an email coming from an IP address that could used by multiple people or a spam bot," he said. "It's a step along the way to regaining trust in email," Crocker added.
The core technologies used in DKIM have been around for years, he said. "We're taking existing pieces and using them together in new ways."
The DomainKeys project was started several years ago by Yahoo as a way to fight phishing and spam; the Identified Internet Mail project was begun by Cisco.
The DomainKeys project was particularly innovative because it specified the use of domain names rather than IP addresses to authenticate senders, Crocker said. DomainKeys also used the existing Domain Name System (DNS) to transmit the public keys needed for encryption, rather than adding yet another infrastructure layer.
An informal consortium of about a dozen IT vendors and organisations, including Yahoo, Cisco, EarthLink, Microsoft, PGP, StrongMail, VeriSign and Sendmail, have met for a year to create the new specifications for DKIM. It was first submitted to the IETF for consideration as a new email standard to fight phishing and spam in July 2005.
To make it work, DKIM now has to be adopted and incorporated by independent software vendors into their email applications and related infrastructures. Paul Hoffman, a director at the Domain Assurance Council, a trade association for the domain reputation industry, said he believes that email service providers such as Yahoo and Google will lead the way.