Claude traces NSA-supplied NIST curve seeds to lrand48, closing a 25-year cryptography mystery

Anthropic reported that its AI model Claude traced the unexplained seeds behind the NIST elliptic curves standardized in 2000 to lrand48, a simple C random number generator initialized with a Unix timestamp between May 1997 and April 1998. The NSA supplied the seeds with no explanation, which fueled backdoor suspicion for 25 years and a public bounty. Claude spotted the pattern in under 30 minutes because lrand48 outputs only 31 bits and the top bits in some seeds were systematically zero, and it reproduced the sequence behind the widely used P-256 curve.

Anthropic published reproduction code, so anyone can rerun the program and retrace the numbers, and it is donating the $36,864 bounty to the Internet Security Research Group. The finding makes a deliberate backdoor in the P-192 through P-521 curves much less likely, though a few elements, including the B-163 seed, some base points, and one skipped candidate, remain unexplained, and users of the NIST curves do not need to take any action.

Sources: The Decoder; CoinDesk