SAN JOSE — For years, anonymous e-mail has been a choice tool for whistle-blowers, human rights activists and undercover sources looking to protect themselves while imparting vital information.
Anonymous online communication could just as easily be used by terrorists to plot attacks or send threats.
Yet little has changed since Sept. 11 for users and operators of Internet-based anonymous e-mail servers, which launder messages by deleting identifying information, rendering them virtually untraceable.
Now there are indications the servers have increased in number.
While no evidence has been released linking such services to any criminal or terrorist conspiracy, experts fear governments could crack down on anonymous remailers — or at least subject them to greater scrutiny.
Law enforcement generally despises technology that leaves such cold trails, said Mark Rasch, former head of the Department of Justice’s computer crimes unit and current vice president of cyberlaw at Predictive Systems.
So far, U.S. and European authorities battling terrorism and cybercrime have apparently focused their surveillance elsewhere. The FBI declined to comment on what strategy, if any, it has for dealing with remailers.
“There’s a lot more concern about border security and banking records,” said Mike Godwin, a policy fellow at the Center for Democracy and Technology.
That’s just fine with the people who operate remailers. They don’t do it for money, but rather share a common ideal of protecting online privacy.
Len Sassaman, an e-mail security consultant who runs a remailer as a hobby, thinks any attempts to crack down would lead to more cropping up around the world.
In fact, the number of remailers overall doubled to about 50 after the passage of security laws as media reports raised awareness of threats to privacy, he said.
“More people are interested in taking steps to protect that,” said Sassaman, who once had his e-mail published online after someone hacked into his Internet service provider.
Some degree of e-mail anonymity can be achieved using a Microsoft Hotmail or Yahoo Mail account with a pseudonym. Encryption hides a message’s contents but not it’s origin or destination.
That’s why people seeking nearly airtight anonymity like to send encrypted messages via remailers.
Anonymous remailers today tend to work in teams, with a single message automatically passing through several. That reflects lessons learned in the case of Julf Hensingius.
In 1993, the Finn developed an anonymous e-mail system that stripped off the identification of an e-mail’s sender before forwarding it to the addressee.
Anon.penet.fi was especially popular among devotees of Usenet newsgroups, text-based bulletin boards that preceded the World Wide Web.
A major flaw was revealed in 1995, however, when the Church of Scientology learned of a user who used Anon.penet.fi to post internal church documents — and contacted police.
Because the single remailer relied on a database to match the sender’s Internet address with the message, the courts simply ordered Hensingius to reveal the identity of the sender. He shut down the service in 1996.
“That prompted a bunch of programmers to rethink how they wanted to do remailers,” said Sassaman.
Now, messages are bounced from machine to machine. In order to find the original sender, authorities would have to work through an entire chain of remailers, many likely located in different countries.
But the development did not stop there.
Programmer Lance Cottrell created the Mixmaster system to further confuse the trail by programming random delays from machine to machine. That makes it impossible to watch the system in order to identify a sender by monitoring when messages arrive and leave.
Moreover, messages are encrypted multiple times, each wrapped inside the other like a matryoshka, or nested Russian doll. The whole message is then broken into packets of equal size. Logs are not kept.
It leaves virtually no trail to follow for authorities.
“Normally, they’re going to subpoena the last remailer in the chain. That’s the only one they can see,” said Cottrell, now chief executive of Anonymizer.com. “There’s just no path to work backward to the original sender.”
Such complexity does not come easy. Software, downloaded for free, must be used by both the receiver and the sender so the messages are encrypted before being sent.
And if one computer in the chain goes down, messages just disappear.
Attempts to commercialize remailer technology have not been successful. In October, the easiest to use, Zero-Knowledge Systems’ Freedom Network, was shut down, due to lack of demand.
Law enforcers have at least one way of unmasking users of anonymous remailers, said Richard Smith, formerly chief technology officer at the Privacy Foundation.
Authorities could ask an Internet provider to list users who have sent data to an anonymous remailer. Then, using the FBI’s “Magic Lantern” or other intrusive eavesdropping programs, officials could secretly record a user’s every keystroke.
“As they’re typing in their secret messages, they get reported before they get encrypted,” Smith said. “That’s the weakness of any encryption system — when the message is being typed or being read.