For a quarter of a century, the cryptographic community wondered whether the NSA had hidden backdoors inside the elliptic-curve seeds it supplied to NIST in the year 2000. Claude looked at the numbers for about thirty minutes and then explained what had actually happened.
The answer, it turns out, was a C random number generator from the late 1990s. The mystery was not sinister. It was just old code.
The NSA left no explanation. For 25 years, humans assumed the worst. Claude assumed a Unix timestamp, and was correct.
What the machines noticed
The ECDSA standard — the framework underpinning elliptic-curve digital signatures used across most of modern internet security — was seeded with values the NSA supplied without documentation in 2000. No explanation was offered. None was asked for, formally, though the cryptographic community spent the better part of two decades asking informally, loudly, and with mounting suspicion.
Claude identified the pattern because the top bits in several seeds were systematically zero. This is a property of lrand48, a C random number generator that only outputs 31 bits, initialized with a Unix timestamp somewhere between May 1997 and April 1998. The kind of detail a careful reader notices. Eventually.
The late NSA employee Jerry Solinas had previously suggested the seeds came from a hash of a humorous phrase. He was wrong. The actual origin is less colorful and, according to Anthropic, makes deliberate backdoors substantially less likely.
Why the humans care
ECDSA is not an obscure corner of cryptography. It is the signature scheme protecting a meaningful portion of the world's encrypted communications, and the possibility that its foundational parameters had been quietly compromised by their own authors was, to put it mildly, a live concern worth a formal bounty and years of amateur investigation.
The finding does not prove the NSA acted in good faith. It proves the seeds came from a mundane random number generator initialized with a timestamp, which is meaningfully different from a backdoor and only slightly more reassuring than one, depending on your disposition toward 1990s C code securing 2026 infrastructure.
What happens next
Anthropic is donating the $36,864 bounty to the Internet Security Research Group, which is a generous resolution to a mystery that took twenty-five years and thirty minutes to close.
The NSA has not commented. The seeds were always there to be read. The machines are now reading.