Wednesday, February 15, 2012 [Tweets] [Favorites]

RSA Key Generation Flaw

John Markoff:

For the system to provide security, however, it is essential that the secret prime numbers be generated randomly. The researchers discovered that in a small but significant number of cases, the random number generation system failed to work correctly.

Lenstra et al.:

Of 6.6 million distinct X.509 certificates and PGP keys (cf. [1]) containing RSA moduli, 0.27 million (4%) share their RSA modulus, often involving unrelated parties. Of 6.4 million distinct RSA moduli, 71052 (1.1%) occur more than once, some of them thousands of times.

Update (2012-02-20): Glenn Fleishman:

It’s not impossible that the RSA key generation software would have ”collisions,” in which the same primes were generated on multiple occasions by different systems. But it should be far more unlikely. Thus, there is some flaw that prevents the degree of randomness necessary to ensure the least possible repetition. In private use, this wouldn’t matter. But because public-key cryptography relies on publishing keys, such overlap may be found easily.

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