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

Nano Banana Pro aka gemini-3-pro-image-preview is the best available image generation model - 20th November 2025
How I automate my Substack newsletter with content from my blog - 19th November 2025
Trying out Gemini 3 Pro with audio transcription and a new pelican benchmark - 18th November 2025

gmp 1 openid 213 php 181

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