Simon Willison’s Weblog

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

How Rob Pike got spammed with an AI slop "act of kindness" - 26th December 2025
A new way to extract detailed transcripts from Claude Code - 25th December 2025
Cooking with Claude - 23rd December 2025

gmp 1 openid 213 php 190

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