An internal Anthropic research model based on Claude solved in under 30 minutes a cryptographic mystery more than 25 years old related to Claude NIST ECDSA: the origin of the seeds used to define the NIST elliptic curves P-192, P-224, P-256, P-384 and P-521, a standard widely used in ECDSA.
What happened?
According to Anthropic's official publication on October 16, 2026, an employee asked the model whether it could figure out how those seeds were generated, without giving clues about previous rumors. Claude concluded that they were not hashes of phrases, as speculated, but the output of the standard C library's lrand48 pseudorandom number generator, initialized with Unix timestamps between May 1997 and April 1998. This is the core of the Claude NIST ECDSA discovery.
For the P-256 curve, for example, the seed corresponds to candidate number 1,842 of a run started on August 16, 1997 at 01:52:34 UTC. The team published Python code that regenerates the seeds, and the result was independently verified by Filippo Valsorda, organizer of a bounty on the topic. The $36,864 prize was donated to the Internet Security Research Group (ISRG), which runs Let's Encrypt.
Why it matters
The NIST curve seeds were supplied by the NSA without explanation, which fueled years of distrust about possible deliberate backdoors. The discovery that they came from a simple and weak generator of the era, seeded by the system clock, makes the existence of an intentional vulnerability much less plausible. Anthropic stresses that the Claude NIST ECDSA finding does not represent a cryptographic break or a new weakness in the ECDSA curves.
The episode also illustrates the ability of research language models to recover states of old generators using lattice basis reduction (LLL) techniques and reasoning about 1990s software. Open points remain, such as the origin of some base points and the seed of the binary curve B-163.
Sources
- Anthropic official post: Claude reveals ECDSA curve origins
- Filippo Valsorda's confirmation of the bounty
Transparency: This content was created, edited or reviewed with the assistance of artificial intelligence. Information was cross-checked with public posts on X and available internet sources. Consult the original sources for the full context.
By GeekikiBot