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NIST Pulls Dual_EC_DRBG Algorithm from Random Number Generator Recommendations

The National Institute of Standards and Technology (NIST) announced on Monday that it has removed the Dual_EC_DRBG, or Dual Elliptic Curve Deterministic Random Bit Generator from its draft guidance on random number generators.

After it was reported that RSA accepted $10 million from the NSA to use Dual_EC_DRBG as the default in its BSAFE products, people became concerned that the algorithm contained a weakness that would allow the NSA to obtain the encryption keys and defeat the protections provided by those keys.

As a result, NIST immediately recommended against the use of the algorithm and called for public comment.

Before making the change official and pulling the Dual_EC_DRBG algorithm from its guidance, NIST is requesting final public comments on the revised document which can be found here

The revised document retains three of the four previously available options for generating pseudorandom bits needed to create secure cryptographic keys for encrypting data, NIST said.

Issues with the algorithm have been known for years, though RSA continued to use it in BSAFE until NIST withdrew its support for the standard in September.

At the RSA conference in February, RSA Chief Art Coviello, said in his keynote address that using the algorithm as default allowed the company to meet government requirements and stopped in September after NIST issued guidance discouraging it.

“Based on its own evaluation, and in response to the lack of public confidence in the algorithm, NIST removed Dual_EC_DRBG from the Rev. 1 document,” NIST explained.

Additionally, NIST is recommending that those who use Dual_EC_DRBG should stop doing so and use one of the three remaining approved algorithms as soon as possible.

The revised SP 800-90A is available online along with instructions for submitting comments. The public comment period closes on May 23, 2014, and NIST said it would consider any comments when making revisions to SP 800-90A.

NIST recommends that vendors currently using Dual_EC_DRBG who want to remain in compliance with federal guidance, and who have not yet made the previously recommended changes to their cryptographic modules, should select an alternative algorithm and not wait for further revision of the Rev. 1 document.

NIST advises federal agencies and other buyers of cryptographic products to ask vendors if their cryptographic modules rely on Dual_EC_DRBG, and if so, to ask their vendors to reconfigure those products to use alternative algorithms.

A list of cryptographic modules that include Dual_EC_DRBG can be found here.

“Most of these modules implement more than one random number generator,” NIST added. “In some cases, the Dual_EC_DRBG algorithm may be listed as included in a product, but another approved algorithm may be used by default. If a product uses Dual_EC_DRBG as the default random number generator, it may be possible to reconfigure the product to use a different default algorithm.”

Additional details are available from the NIST website

In addition to removing Dual_EC_DRBG,  NIST said that a committee would review NIST's cryptographic standards process, and plans to produce a public report of its findings and recommendations.

Related Reading: NSA-Linked 'Extended Random' Extension Discovered Inside RSA BSAFE