Karsten Nohl, a 28-year-old German native,
reportedly cracked the code and has published his findings to the
computer and electronics hacking community. Mr. Nohl, who cites
a strong interest in protecting the privacy of citizens against
from any party, says that his work showcases the outdated
At the Chaos Communication Congress, a
four-day conference of computer hackers that runs through Wednesday
in Berlin, he revealed his accomplishments. He describes, "This
shows that existing GSM security is inadequate. We are trying
to push operators to adopt better security measures for mobile phone
The GSM Association, the London-based group that
developed the standard and represents wireless companies, was quick
to blast the publication calling Mr. Nohl's actions illegal and
counterintuitive to the desire to protect the privacy of mobile phone
calls. However, they insist that the publication in no way
threatens the standard's security.
Claire Cranton, an
association spokeswoman, confirmed that Mr. Nohl was the first to
break the code, commenting, "[Security threats from the
publication of this standard are] theoretically possible but
practically unlikely. What he is doing would be illegal in
Britain and the United States. To do this while supposedly being
concerned about privacy is beyond me."
Mr. Nohl attended
college in the U.S. and received a PhD in computer engineering from
the University of Virginia. Via a similar publication, he
managed to convince the DECT Forum, a separate standards group based
in Bern, to upgrade its own security algorithm, improving the
protection to the standard's 800 million customers in the
And while the trade group is only on yellow alert,
some security experts disagree with the group's threat analysis, as
well, saying the threat could be far more serious. One expert
suggested that calls may soon need to be scanned for malicious
activity, much as an antivirus scanner works on a computer.
Schatt, a vice president for health care and security at the
technology market researcher ABI Research in New York, opines,
"Organizations must now take this threat seriously and assume
that within six months their organizations will be at risk unless
they have adequate measures in place to secure their mobile phone
The process of cracking the algorithm involved
the help of 24 members of the Chaos Computer Club in Berlin, who
helped generate the random combinations needed to try and reproduce
the standard's code book, so to speak. The vast log of binary
combinations forms the basis of the A5/1 encryption -- and how to
undo it. And it's now on torrents worldwide.
that, Mr. Nohl insists that his actions aren't illegal. He says
he took great precautions to make sure his work was kept purely
academic, in the public domain, and that it was not used to crack any
actual digital telephone calls. He states, "We are not
recommending people use this information to break the law. What
we are doing is trying to goad the world’s wireless operators to
use better security."
A5/1 is a 64-bit security
algorithm. Despite this particular algorithm's run, 64-bit
encryption is considered weaker by today's standards. Today
128-bit algorithms are considered to be strong enough to protect most
data. The GSM Association has devised a 128-bit successor to
A5/1, dubbed A5/3, but it has failed to push the standard out across
much of the industry.
The Association claims that there's
little danger of calls being intercepted as hackers would have to
pick one call stream out of thousands at a cell phone tower.
They say that this would take prohibitively expensive sophisticated
equipment and software. Security experts disagree with this
assessment -- including Mr. Nohl who pointed out that there was a
wealth of open
source software and cheap equipment to accomplish exactly those
sort of objectives.
Simon Bransfield-Garth, the chief
executive of Cellcrypt, a company based in London that sells
software, agrees, saying that the publications opens call
interception to "any reasonable well-funded criminal
organization". He adds, "This will reduce the time to
break a GSM call from weeks to hours. We expect as this further
develops it will be reduced to minutes."
Why is that a
big deal? Over 3.5 billion people use GSM worldwide, including
299 million in North America.