Claude traced NIST curve seeds to 1990s Unix timestamps

"It's just timestamps," Anthropic writes about the seeds behind ECDSA's NIST curves. The NSA supplied them with no explanation, and NIST adopted them in 2000.

Anthropic staff had chased a rumor that the seeds hashed a joke phrase, with no luck. Asked without that hint, an internal research model found in under half an hour that the P-192 to P-521 seeds came from the C lrand48 generator, seeded with Unix timestamps from May 1997 to April 1998.

The giveaway was in the top bits. Four of ten seeds had a zero top bit in all 20 words, odds of 1/5810, and lrand48 returns only the top 31 bits of its 48-bit state.

The B-163 seed and the P-224, P-256, P-384 and P-521 base points remain unexplained. In our view, a seed anyone can rebuild from a 1997 clock reading beats any joke passphrase as proof.