Anthropics' Claude cracks a 25-year-old NSA cryptography mystery in under 30 minutes
Claude traced NIST's unexplained ECDSA curve seeds to lrand48 initialized with a 1997-1998 Unix timestamp.
NIST standardized several ECDSA elliptic curves in 2000 using seeds supplied by the NSA without explanation, long fueling backdoor suspicions. Anthropic says Claude identified those seeds as output from the C generator lrand48, initialized with a Unix timestamp between May 1997 and April 1998, in under 30 minutes. The model noted that lrand48 emits only 31 bits, matching systematically zero high bits in some seeds. Anthropic says this origin makes a deliberate backdoor less likely and is donating the $36,864 bounty to the Internet Security Research Group.
- NSA-supplied NIST ECDSA seeds from 2000 had no public explanation.
- Claude tied the seeds to lrand48 and a 1997-1998 Unix timestamp.
- lrand48's 31-bit output matched zeroed high bits in some seeds.
- Anthropic says the finding makes a deliberate backdoor less likely.
- The $36,864 bounty will go to the Internet Security Research Group.
Full article215 words · extracted from the-decoder.com · click to collapse
Oct 17, 2026
Anthropic's AI Claude has solved a 25-year-old cryptography mystery. NIST standardized several curves in the ECDSA standard, the most widely used framework for elliptic-curve digital signatures, back in 2000. The NSA had supplied the seeds, the starting values used to generate the curve parameters, with zero explanation. No one knew how they were created, and that fueled suspicion of possible backdoors. The mystery even attracted a bounty and amateur sleuthing efforts. The late NSA employee Jerry Solinas had suggested the seeds were a hash of a humorous phrase, but that turned out to be wrong.
Claude cracked it in under 30 minutes. The seeds came from "lrand48," a simple C random number generator, initialized with a Unix timestamp between May 1997 and April 1998. Claude spotted the pattern because "lrand48" only outputs 31 bits, and the top bits in some seeds were systematically zero. According to Anthropic, this makes deliberate backdoors less likely. Anthropic is donating the $36,864 bounty to the Internet Security Research Group.
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