Simon Willison’s Weblog

Every time I get into an online conversation about prompt injection it's inevitable that someone will argue that a mitigation which works 99% of the time is still worthwhile because there's no such thing as a security fix that is 100% guaranteed to work.

I don't think that's true.

If I use parameterized SQL queries my systems are 100% protected against SQL injection attacks.

If I make a mistake applying those and someone reports it to me I can fix that mistake and now I'm back up to 100%.

If our measures against SQL injection were only 99% effective none of our digital activities involving relational databases would be safe.

I don't think it is unreasonable to want a security fix that, when applied correctly, works 100% of the time.

(I first argued a version of this back in September 2022 in You can’t solve AI security problems with more AI.)