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

Useful patterns for building HTML tools - 10th December 2025
Under the hood of Canada Spends with Brendan Samek - 9th December 2025
Highlights from my appearance on the Data Renegades podcast with CL Kao and Dori Wilson - 26th November 2025

gmp 1 openid 213 php 190

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