RSA: That NSA crypto-algorithm we put in our products? Stop using that

Encryption key tool was dodgy in 2007, and still dodgy now

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Security biz RSA has reportedly warned its customers to stop using the default random-number generator in its encryption products - amid fears spooks can easily crack data secured by the algorithm.

All encryption systems worth their salt require a source of virtually unpredictable random values to create strong cryptographic keys and similar things; one such source is the NSA-co-designed pseudo-random-number generator Dual_EC_DRBG, or the Dual Elliptic Curve Deterministic Random Bit Generator, which is well known for being cryptographically weak: six years ago it was claimed that someone had crippled the design, effectively creating a backdoor [PDF] so that encryption systems that relied on it could be easily cracked.

RSA's BSafe toolkit and Data Protection Manager software use Dual_EC_DRBG by default. Now the EMC-owned company "strongly recommends" customers pick another pseudo-random-number generator (PRNG) in their setups. This comes after documents leaked by whistleblower Edward Snowden allegedly show that the NSA nobbled Dual_EC_DRBG during its inception - which could allow the spook nerve-centre to crack HTTPS connections secured by RSA's BSafe software, for example.

The suspect algorithm, championed by the NSA according to security expert Bruce Schneier, was given the seal of approval and published by the US government's National Institute of Standards and Technology (NIST) in 2006. But a year later researchers at Microsoft highlighted fundamental flaws its design: crypto-prof Matthew Green lays out the history and faults of the PRNG here.

Since Snowden's leaks came to light, NIST has denied weakening this particular PRNG - one of four approved for wider use in 2006 - at the behest of shadowy g-men. However, earlier this month, Schneier said NIST needs to go much further to restore confidence in its practices and procedures, especially when doubts linger about the robustness of Dual_EC_DRBG.

Cryptographers have known for literally years that Dual_EC_DRBG was slow and not especially effective, leading to criticism that RSA was wrong to pick it as a default option for BSafe - and the more paranoid to question its motives.

"Despite many valid concerns about this generator, RSA went ahead and made it the default generator used for all cryptography in its flagship cryptography library," noted Green late last week. "The implications for RSA and RSA-based products are staggering. In a modestly bad but by no means worst case, the NSA may be able to intercept SSL/TLS connections made by products implemented with BSafe."

"So why would RSA pick Dual_EC as the default? You got me,” shrugged Green, who is a research professor at Johns Hopkins University in Baltimore. “Not only is Dual_EC hilariously slow - which has real performance implications - it was shown to be a just plain bad random number generator all the way back in 2006. By 2007, when [cryptographers Dan] Shumow and [Niels] Ferguson raised the possibility of a backdoor in the specification, no sensible cryptographer would go near the thing."

RSA's CTO Sam Curry defended RSA's choices in an interview with Ars Technica. RSA is reviewing all its products, he confirmed. Green was unimpressed by the RSA man's claims.

Curry was quoted as explaining in an email: "The hope was that elliptic curve techniques — based as they are on number theory — would not suffer many of the same weaknesses as other techniques (like the FIPS 186 SHA-1 generator) that were seen as negative, and Dual_EC_DRBG was an accepted and publicly scrutinized standard."

The NSA's alleged weakening of encryption algorithms was part of a wider campaign aimed at making it easier for spooks to decrypt supposedly secure internet communications, first outlined in the New York Times two weeks ago. Other tactics include attempting to persuade technology companies to insert backdoors in their products, including it is claimed Microsoft's Outlook.com, and running so-called man-in-the-middle attacks to hoover up the world's online chatter and transactions. ®

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