Who uses Dual_EC_DRBG? Recent news articles have suggested that the NSA may be involved in trying to influence the cryptography in public standards or commercially deployed software, to enable the NSA to decrypt the encrypted traffic.  For example, see this article in the New York Times.

The New York Times article specifically mentions a 2006 NIST standard, where two Microsoft engineers later discovered a serious problem in the scheme.  The New York Times article explains how the standard was written by the NSA, who pushed the scheme hard:


  Simultaneously, the N.S.A. has been deliberately weakening the international encryption standards adopted by developers. One goal in the agency’s 2013 budget request was to “influence policies, standards and specifications for commercial public key technologies,” the most common encryption method.
  
  Cryptographers have long suspected that the agency planted vulnerabilities in a standard adopted in 2006 by the National Institute of Standards and Technology, the United States’ encryption standards body, and later by the International Organization for Standardization, which has 163 countries as members.
  
  Classified N.S.A. memos appear to confirm that the fatal weakness, discovered by two Microsoft cryptographers in 2007, was engineered by the agency. The N.S.A. wrote the standard and aggressively pushed it on the international group, privately calling the effort “a challenge in finesse.” 


After some sleuthing, I'm pretty certain this is a reference to the Dual_EC_DRBG pseudorandom number generator scheme described in NIST SP 800-90.  The weakness is that Dual_EC_DRBG appears to contain a backdoor, and anyone who knows the backdoor can totally break the PRNG.  The weakness was first described in a rump session talk at CRYPTO 2007 and was subsequently discussed by Bruce Schneier in Wired.

As a consequence, there are now good reasons to suspect that Dual_EC_DRBG contains a NSA backdoor, and the NSA might be able to spy on anyone who is using Dual_EC_DRBG.

My questions:


Who uses Dual_EC_DRBG?
Do any commercial products use Dual_EC_DRBG?
Does anyone use it?
Here is a list of products and companies who have had their EC DRBG algorithm validated by NIST.
http://csrc.nist.gov/groups/STM/cavp/documents/drbg/drbgval.html

The validation lists all modes that have been validated, so you can see which ones have gone to the effort of having their implementation of Dual_EC_DRBG validated.  Tim Dierks points out that, for Lancope's certification (NIST validation #288), Dual_EC_DRBG is the only listed mode of operation that was tested or validated.  It's hard to know why Lancope would have submitted their library for validation if they weren't using it.  So, it sounds like there exists at least one implementation in the wild that uses Dual_EC_DRBG.  (Thanks to Tim Dierks for this analysis.)