Filippo Valsorda

Stories

Anthropic team solves NIST curve seed mystery, claims bounty

Verified the Anthropic team's solution and announced the claim

The seed numbers behind NIST's elliptic curves came from the C library's lrand48 random number generator, seeded with Unix timestamps from 1997 and 1998. The long-running tip that they were hashes of a humorous phrase was wrong.

Updated Nov 1

Weak eMudhra certificate keys trigger global TLS cleanup

New Capabilities

Publicly assessed the scale of the cleanup

Eight intermediate certificates from eMudhra, an Indian certificate authority, had private keys a computer could guess in under a second. eMudhra first blamed an April 2025 key-generation ceremony, then acknowledged on October 26 that a script error produced the weak keys. Browsers and operating systems are now removing trust in the parent root, not just the eight certificates.

Updated Oct 30

Go blocks trust in eight eMudhra certificate intermediates

Rule Changes

Said the keys are compromised and the certificates revoked, and that blocking them in Go's code was the only option for now

Go has released versions 1.27.3 and 1.26.10 that refuse any TLS certificate chain built on one of eight compromised eMudhra intermediate keys. Researchers say the keys were weak enough that an attacker could forge a trusted certificate for any domain and impersonate the site.

Updated Oct 21

Notable Quotes

Turns out memory can play tricks on everyone: we now know they were instead generated with the POSIX-standard drand48 random number generator.

from Anthropic team solves NIST curve seed mystery, claims bounty · Updated Nov 1

There will be a very, very long tail, IoT devices, Docker containers, forgotten Linux machines, unmaintained CLI tools that shipped their own copy of the roots (which is common in some ecosystems, like Python).

from Weak eMudhra certificate keys trigger global TLS cleanup · Updated Oct 30