[cryptography] Extended Random is extended to whom, exactly?

ianG iang at iang.org
Mon Mar 31 13:36:32 EDT 2014


(Reuters) - Security industry pioneer RSA adopted not just one but two
encryption tools developed by the U.S. National Security Agency, greatly
increasing the spy agency's ability to eavesdrop on some Internet
communications, according to a team of academic researchers.

A group of professors from Johns Hopkins, the University of Wisconsin,
the University of Illinois and elsewhere now say they have discovered
that a second NSA tool exacerbated the RSA software's vulnerability.

The professors found that the tool, known as the "Extended Random"
extension for secure websites, could help crack a version of RSA's Dual
Elliptic Curve software tens of thousands of times faster, according to
an advance copy of their research shared with Reuters.

In a Pentagon-funded paper in 2008, the Extended Random protocol was
touted as a way to boost the randomness of the numbers generated by the
Dual Elliptic Curve.

But members of the academic team said they saw little improvement, while
the extra data transmitted by Extended Random before a secure connection
begins made predicting the following secure numbers dramatically easier.

"Adding it doesn't seem to provide any security benefits that we can
figure out," said one of the authors of the study, Thomas Ristenpart of
the University of Wisconsin.

Johns Hopkins Professor Matthew Green said it was hard to take the
official explanation for Extended Random at face value, especially since
it appeared soon after Dual Elliptic Curve's acceptance as a U.S. standard.

"If using Dual Elliptic Curve is like playing with matches, then adding
Extended Random is like dousing yourself with gasoline," Green said.

The NSA played a significant role in the origins of Extended Random. The
authors of the 2008 paper on the protocol were Margaret Salter,
technical director of the NSA's defensive Information Assurance
Directorate, and an outside expert named Eric Rescorla.

END of snippets, mostly to try and figure out what this protocol is
before casting judgement.  Anyone got an idea?


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