Re: [fxtf-drafts] [css-compositing-2] Add plus-lighter to mix-blend-mode and background-blend-mode (#444)

After we shipped this feature with blend modes that weren't susceptible to time, someone on the skia team refactored the formulas which enabled a time attack. See https://arstechnica.com/information-technology/2018/05/chrome-and-firefox-leaks-let-sites-steal-visitors-facebook-names-profile-pics/
You need to make sure that `plus-lighter` executes the same regardless of its input. Since there's a `min(..., ...)`, there might be an `if` block in the implementation which would introduce a timing attack. 

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Received on Friday, 14 January 2022 17:10:01 UTC