Claude Cracks 25-Year-Old Mystery Behind NSA's ECDSA Curves in Half an Hour

In 2000, NIST, the US standards agency, picked a set of elliptic curves for ECDSA, the signature standard that protects much of the internet. The seed numbers for these curves came from the NSA (the US National Security Agency) with no explanation at all. That left a 25-year-old mystery, and plenty of suspicion about a hidden backdoor. Anthropic's Claude model found that these numbers carry the fingerprint of lrand48, an old random number generator from a 1990s software library that only outputs 31 bits. Using its zeroed-out high bits, Claude reconstructed the original timestamps. Most of them fall between May and August 1997, with one from April 1998. The whole analysis took Claude less than half an hour.

This is not a party trick. It is a case where a large-model-based agent solved a technical puzzle that researchers could not crack by hand for decades, and it delivered a verifiable result in half an hour instead of just smooth-sounding text. Anthropic itself stays honest here: some of the numbers remain unexplained, so calling the backdoor question fully closed would be premature. Trust in the model for serious work grows out of cases like this, not out of marketing promises.