As of: 2026-10-17 22:10 CEST.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/p/2026-10-16-matthew-green-ecdsa-open-questions/

# Matthew Green: 'Well, this is the interesting part now' (skipped candidate curves)

Matthew Green (@matthew_d_green), X, 2026-10-16.
Source: https://x.com/matthew_d_green/status/2111183021906797039

## Why it matters

Johns Hopkins cryptographer (~22k views) points to the open question in Anthropic's post: some viable candidate curves were skipped before the published ones.

## Summary

Posted Fri Oct 16 19:50:30 +0000 2026 by Matthew Green (@matthew_d_green); 22,409 views, 367 likes, 22 reposts when read via api.fxtwitter.com on 2026-10-17. Screenshot of the 'Open questions' section of Anthropic's post: for P-256 the published seed is candidate 1842 but candidate 876 also gives a valid curve; 'We do not know what criteria may have been used, or whether this was an unintentional artifact.'

## Archived text

> Well, this is the interesting part now.

Archived 2026-10-17 via fxtwitter (unofficial).
Counts: 22,457 views, 368 likes, 22 reposts, 13 replies (at fetch time)
Media: https://pbs.twimg.com/media/HUxtxPFXgAAcRuJ.jpg?name=orig

## Cited in

- 2026-10-16: [Claude explains where the NIST P-256 curve seeds came from](https://postcutoff.com/e/2026-10-16-claude-recovers-nist-ecdsa-curve-seeds/)