Hi guys, I just looked at a note on my desk, which asked if we currently cache the bytes generated by the pseudo-random functions -- putting them into some kind of pool so that we can save the number of SHA-1 calls.
We don't, and the reason is that the PRFs are used as follows when we do pseudo-random secret sharing: r = PRF(program_counter) Here we might produce 20 random bytes and only use, say, 65 bit of them, but future randomness will be generated with different program counters, and so we cannot easily cache it. It is of course not impossible to do something :-) We could do the same as what we do when we generate multiplication triples using the hyper-invertible matrices. There we generate T triples and assign the triples to known program counters -- we could in principle start the computation by generating in advance all the randomness we need and distribute it nicely over the tree of program counters. The change would require a fair amount of code, and it's anybody's guess if the added complexity will pay off. -- Martin Geisler VIFF (Virtual Ideal Functionality Framework) brings easy and efficient SMPC (Secure Multiparty Computation) to Python. See: http://viff.dk/. _______________________________________________ viff-devel mailing list (http://viff.dk/) viff-devel@viff.dk http://lists.viff.dk/listinfo.cgi/viff-devel-viff.dk
