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A comment on Architecting Websites for the HTTP/2 Era. Parent comment

Re:Architecting Websites for the HTTP/2 Era by strommen on Tuesday May 12, 2015 @03:45PM (#9534363)
Not really. The theory behind the attack is that if the user-specified content is equal to the secret content, it will compress more effectively and have a smaller content length. The other content on the page doesn't really matter.

Adding data of random length will make the attack more difficult, but won't defeat it entirely. This is called length hiding.

See http://breachattack.com/ for a more thorough explanation by smarter people.

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Re:Architecting Websites for the HTTP/2 Era by nine_k on Tuesday May 12, 2015 @03:57PM (#9534431)
The attack depends on a secret to match a user-provided string enough for the compression algorithm to notice this redundancy?

A counter-measure then would be to scramble the user input in the page with a random key, and include this key into the page for de-scrambling using JavaScript. It will still efficiently compress the parts of the page which are not user-controlled.

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Re:Architecting Websites for the HTTP/2 Era by strommen on Tuesday May 12, 2015 @05:24PM (#9535002)
Yes and Yes (assuming your random key isn't guessable).

breachattack.com suggests masking the secret with a per-request random key, but masking the user input would work too.

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Re:Architecting Websites for the HTTP/2 Era by nickysielicki on Tuesday May 12, 2015 @05:14PM (#9534935)
> de-scrambling using JavaScript

No thank you.

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