Simon Willison’s Weblog

Don't Hash Secrets. A well written explanation from 2008 of why you must use hmac instead of raw SHA-1 when hashing against a secret.

Posted 24th January 2010 at 1:30 pm

Recent articles

Wilson Lin on FastRender: a browser built by thousands of parallel agents - 23rd January 2026
First impressions of Claude Cowork, Anthropic's general agent - 12th January 2026
My answers to the questions I posed about porting open source code with LLMs - 11th January 2026

cryptography 24 hmac 2 security 573 sha1 4 signing 6

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