In a new article in an academic math journal, the NSA’s former director of research says that the agency’s decision not to withdraw its support of the Dual EC_DRBG random number generator after security researchers found weaknesses in it and questioned its provenance was a “regrettable” choice.
Michael Wertheimer, the former director of researcher at the National Security Agency, wrote in a short piece in Notices, a publication of the American Mathematical Society, that even during the standards development process for Dual EC many years ago, members of the working group focused on the algorithm raised concerns that it could have a backdoor in it. The algorithm was developed in part by the NSA and cryptographers were suspect of it from the beginning.
Then, in 2007, well into the life of Dual EC, researchers at Microsoft delivered a talk at a conference that detailed the potential for a backdoor in the algorithm. Still, both the NSA and NIST, which approves technical standards for the United States government, stood by the algorithm. Dual EC was mostly forgotten until late 2013 when allegations emerged that the NSA may have had a secret $10 million contract with RSA Security that prompted the vendor to make Dual EC–which was then known to be weak–the default random number generator in some of its key crypto products. NIST last year removed Dual EC from its guidance on random number generators.
“I wrote about it in 2007 and said it was suspect. I didn’t like it back then because it was from the government,” crypto pioneer Bruce Schneier told Threatpost in September 2013. “It was designed so that it could contain a backdoor. Back then I was suspicious, now I’m terrified.”
NSA should have ceased supporting the dual EC_DRBG algorithm immediately after security researchers discovered the potential for a trapdoor
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The NSA came under heated criticism for the Dual EC episode, and now one of the agency’s top officials has said it was a mistake for the NSA not to have withdrawn its support for the algorithm after the weaknesses were raised years ago.
“With hindsight, NSA should have ceased supporting the dual EC_DRBG algorithm immediately after security researchers discovered the potential for a trapdoor. In truth, I can think of no better way to describe our failure to drop support for the Dual_EC_DRBG algorithm as anything other than regrettable,” Wertheimer wrote in a piece in Notices’ February issue.
“The costs to the Defense Department to deploy a new algorithm were not an adequate reason to sustain our support for a questionable algorithm. Indeed, we support NIST’s April 2014 decision to remove the algorithm. Furthermore, we realize that our advocacy for the DUAL_EC_DRBG casts suspicion on the broader body of work NSA has done to promote secure standards. Indeed, some colleagues have extrapolated this single action to allege that NSA has a broader agenda to ‘undermine Internet encryption.'”
Wertheimer said that the agency is trying to combat that perception by changing the way that it contributes to standards efforts in order to be more transparent and accountable.
“One significant, and correct, change is that all NSA comments will be in writing and published for review. In other words, we will be open and transparent about our cryptographic contributions to standards. In addition, we will publish algorithms before they are considered for standardization to allow more time for public scrutiny,” Wertheimer wrote.
“With these measures in place, even those not disposed to trust NSA’s motives can determine for themselves the appropriateness of our submissions, and we will continue to advocate for better security in open-source software, such as Security Enhancements for Linux and Security Enhancements for Android.”
This article was updated on Jan. 16 to reflect Wertheimer’s correct title.
