By John Leyden the Register
Published Thursday 8th November 2007 13:36 GMT
US federal law enforcement agencies have obtained access to clear text
copies of encrypted emails sent through Hushmail as part a of recent
drug trafficking investigation.
The access was only granted after a court order was served on Hush
Communications, the Canadian firm that offers the service.
Hush Communications said it would only accede to requests made in
respect to targeted accounts and via court orders filed through Canadian
Nonetheless, the incident illustrates that Hushmail's marketing claims
that not even its own staff can access encrypted email is well wide of
September cour t documents (pdf) from a US federal prosecution of alleged
steroid dealers reveals that Hush turned over 12 CDs involving emails on
three targeted Hushmail accounts, in compliance of court orders made
through the mutual assistance treaty between the US and Canada.
Hushmail is widely used by privacy advocates and the security-conscious
to send confidential emails. The service uses robust cryptographic and
encryption protocols (OpenPGP and AES 256) to scramble the contents of
messages stored on its servers, and to exchange encrypted messages with
other encrypted email users.
Breaking messages encrypted by the service by brute force would be
nigh-on impossible. So how was access to clear-text messages obtained?
An investigation by Wired reveals that a server-side encryption option
introduced by Hushmail in 2006 means that a copy of a user's passphrase,
which gives access to encrypted messages, might be obtained.
"In the case of the alleged steroid dealer, the feds seemed to compel
Hushmail to exploit this hole, store the suspects' secret passphrase or
decryption key, decrypt their messages, and hand them over," Wired reports.
Brewing up a storm
Hushmail introduced the server-side encryption option because some users
found installing and running a Java applet to be slow and annoying. In
its original form this Java applet was used to perform the encryption
and decryption of messages on a user's computer.
In this scenario, a clear text copy of a message would never hit
Hushmail's servers so Hush would only be able to respond to law
enforcement requests with scrambled messages, at least in theory. In
practice, Hushmail's Java architecture still permits a mechanism for the
recovery of scrambled emails in clear-text form.
Brian Smith, chief technology officer of Hushmail, declined to speak
about specific law enforcement requests. However he was more forthcoming
in explaining the technology implications of Hushmail's server-side
"The key point, though, is that in the non-Java configuration, private
key and passphrase operations are performed on the server-side. This
requires that users place a higher level of trust in our servers as a
trade off for the better usability they get from not having to install
Java and load an applet," he said.
"This might clarify things a bit when you are considering what actions
we might be required to take under a court order. Again, I stress that
our requirement in complying with a court order is that we not take
actions that would affect users other than those specifically named in
the o rder."
As Wired notes, Hushmail's marketing collateral fails to stress the
implications of using the non-Java option. Even the Java option might
not be entirely secure. Hush may be obliged to rig the Java applet sent
to targeted users with a backdoor designed to capture their passwords,
It explains that "Hushmail's own threat matrix includes this
possibility, saying that if an attacker got into Hushmail's servers,
they could compromise an account - but that 'evidence of the attack'
(presumably the rogue Java applet) could be found on the user's computer."
The upshot of this is that a paranoid user might be able to detect - if
not prevent - if his Hushmail account is being interfered with, but only
if he uses the Java applet option.
"This means that in Java mode the level of trust the user must place in
us is somewh at reduced, although not eliminated," Hushmail's Smith told
Wired. "The extra security given by the Java applet is not particularly
relevant, in the practical sense, if an individual account is targeted."
Smith told Wired that those looking to Hushmail as a safe haven for
snooping on illegal activity were out of luck. However, he added that
the firm, unlike US telecoms firms involved in the controversy over the
Bush administration's warrantless wiretapping program, would resist mass
"[Hushmail] is useful for avoiding general Carnivore-type government
surveillance, and protecting your data from hackers, but definitely not
suitable for protecting your data if you are engaging in illegal
activity that could result in a Canadian court order," Smith told Wired.
"That's also backed up by the fact that all Hushmail users agree to our
&g t; terms of service, which state that Hushmail is not to be used for
illegal activity. However, when using Hushmail, users can be assured
that no access to data (including server logs, etc.) will be granted
without a specific court order.
"We receive many requests for information from law enforcement
authorities, including subpoenas, but on being made aware of the
requirements, a large percentage of them do not proceed," said Smith.
"To date, we have not challenged a court order in court, as we have made
it clear that the court orders that we would accept must follow our
guidelines of requiring only actions that can be limited to the specific
user accounts named in the court order. That is to say, any sort of
requirement for broad data collection would not be acceptable."
Monday, November 19, 2007
By John Leyden the Register