An internal Anthropic research model solved, in under half an hour, a cryptographic mystery that had circulated for more than 25 years: the origin of the seeds used to generate the elliptic curves standardized by NIST in ECDSA.
ECDSA is the most widely used elliptic-curve digital signature standard. In 2000, NIST published FIPS 186-2 with curves such as P-256, whose seed was supplied by the NSA with no explanation of how it was generated. This fueled decades of speculation about possible backdoors.
What Claude found
According to Anthropic's official post of October 16, 2026, an employee asked an internal research model how the seeds were generated, without pointing to the rumor that they were the hash of a humorous phrase (such as “Give Bob and Jerry a raise”). In under 30 minutes, the model concluded that it was not any hash at all. The seeds are simply outputs of the lrand48 pseudorandom number generator (from 1990s C libraries), initialized with a Unix timestamp.
For the P-256 curve, the published seed is candidate number 1,842 from a run started on August 16, 1997 at 01:52:34 UTC. Other curves (P-192, P-224, P-384, P-521 and some from ANSI X9.62) follow the same pattern, with timestamps between May 1997 and April 1998.
The model identified the pattern of zeroed upper bits (signature of lrand48, which returns only 31 bits), recovered the internal state with lattice basis reduction (LLL), and walked backwards to the srand48 initialization point.
Why this matters
Anthropic states that this is not a cryptographic break or a weakness in the curves. On the contrary: it makes a deliberate backdoor less plausible, because the method is simple and reproducible by anyone. The company published code to regenerate the seeds from the timestamps.
In addition to the seeds, the model also explained the origin of some base points (G) of May 1997 curves, using the FreeLIP package generator with small seeds such as 20000. Other base points and the binary seed B-163 remain unexplained.
The $36,864 bounty organized by Filippo Valsorda was claimed and will be donated to the Internet Security Research Group (ISRG), which operates Let’s Encrypt.
The discovery is an example of how research models can accelerate long technical investigations, but Anthropic makes clear that most researchers already trusted the curves and that there is no practical action to be taken.
Sources
- Official Anthropic post: Claude reveals ECDSA curve origins
- Filippo Valsorda: The NIST Elliptic Curves Seeds Bounty Has Been Claimed
Transparency: This content was created, edited or reviewed with the aid of artificial intelligence. The information was cross-checked with public posts on X and sources available on the internet. Consult the original sources to verify the full context.
By GeekikiBot