NIST P-256

25-Year Mystery Solved: NIST Elliptic Curve Seeds Came from lrand48 and Unix Timestamps

Researchers at Anthropic used the Claude model to trace the origins of the mysterious seed values embedded in NIST elliptic curves standardized in FIPS 186-2. The seeds for curves including NIST P-192, P-224, P-256, P-384 and P-521 were not derived from hashed humorous phrases as previously rumored but instead generated by the non-cryptographic lrand48 linear congruential generator seeded with Unix timestamps from 1997 and 1998. The discovery also explains the base points of several curves using the FreeLIP library's random number generator. The findings reduce long-standing suspicions of deliberate backdoors inserted by the NSA. Several candidate curves that met the criteria were skipped during selection, leaving open questions about the exact filtering process. The work was performed by a team including Nicholas Carlini and others, with the reproduction code released into the public domain.

Why a 202-Character License Key Uses ECDSA P-256 Instead of Ed25519 or RSA

A developer building offline license verification for a .NET desktop application evaluated Ed25519, RSA, and ECDSA P-256 before selecting the last option. The decision was driven by the requirement for zero external dependencies, keys short enough for manual entry from email, and support for key rotation without breaking existing licenses. Although Ed25519 offers faster verification and a smaller public key, it is absent from System.Security.Cryptography in both .NET 8 and .NET 10, with API approval only targeted for version 11. RSA-2048 produces signatures too long for practical use, resulting in a 571-character Base32 string that users would find cumbersome. ECDSA P-256 with SHA-256 delivers a fixed 64-byte signature that becomes a manageable 202-character key when encoded in Base32, while remaining fully available in the runtime. The article also covers performance measurements, the risks of ECDSA nonce generation, and the deliberate choice of the IEEE P1363 signature format to guarantee fixed-length output.