[Haskell-cafe] Tor project

Tobias Florek haskell at ibotty.net
Fri Aug 1 09:35:01 UTC 2014


 > Just wanted to say that what I posted might give hope for such
> "branchless" code (or in fact: code that may branch, but by
> construction not in a detectable way).

i don't have the papers handy, but on the same host you can observe 
cache line collisions. that means you cannot do something different that 
takes the same time and generates the same amount of heat. you will have 
to do _the same thing_. of course packages like vincent hanquez 
securemem provide that kind of equality checks (and other very useful 
properties). so some building blocks are there. interaction with the 
garbage collector is still something to worry about though. in some gcs 
you can observe whether a string is in use somewhere in the program or 
not. i am not intimate with ghc's gc but i don't expect that particular 
vulnerability is a problem when using securemem (or even bytestring or 
text), but there might (and i assume will) be many other opportunities 
to observe some state from outside the program.

don't let me discourage you though. every step to less side channels is 
a valuable step!


More information about the Haskell-Cafe mailing list