Simon Willison’s Weblog

15th February 2007 - Link Blog

PHP and "OpenID authentication failed: Bad signature". If you’re seeing a “Bad signature” error in your PHP OpenID application it could be down to a miscompiled GMP library.

Posted 15th February 2007 at 10:02 am

Recent articles

Running Python code in a sandbox with MicroPython and WASM - 6th June 2026
Claude Opus 4.8: "a modest but tangible improvement" - 28th May 2026
I think Anthropic and OpenAI have found product-market fit - 27th May 2026

This is a link post by Simon Willison, posted on 15th February 2007.

gmp 1 openid 213 php 190

Monthly briefing

Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments.

Pay me to send you less!

Sponsor & subscribe