> On 20 Nov 2015, at 10:59, George Kadianakis <[email protected]> wrote: > > David Goulet <[email protected] <mailto:[email protected]>> writes: > >> On 19 Nov (14:30:47), Jacob Appelbaum wrote: >>> Hi George, >>> >>> On 11/12/15, George Kadianakis <[email protected]> wrote: >>>> Hello there believers of prop250, >>>> >>>> you can find the latest version of the proposal in the upstream torpec >>>> repo: >>>> >>>> https://gitweb.torproject.org/torspec.git/tree/proposals/250-commit-reveal-consensus.txt >>> >>> I reviewed your fine document and I wondered about section 4.1.1. and >>> specifically about the generation of RN "where RN is a 256-bit random >>> value." >>> >>> I'd like to propose a change that is minimal and adds only one small change: >>> >>> The value REVEAL is computed as follows: >>> >>> REVEAL = base32-encode( TIMESTAMP || H(RN) ) >>> >>> where RN is a 256-bit random value and where H is the hashing >>> algorithm "sha256". >>> >>> This would ensure that the raw random bytes from the PRNG are never >>> revealed to the network which seems like a reasonable thing[0] to >>> prevent. >> >> Interesting! This sounds like a good thing to do and very little change >> needed for additional security. >> >> George, if you are OK with this, I can change the proposal and push it >> upstream. Will change the code after that. >> > > Sounds good to me. > > The commitment structure will also have to change to commit H(H(RN)). > > For spec readability, maybe we could have: > > RN = 255-bit random number > REVEAL_VALUE = H(RN) > > and then use REVEAL_VALUE in REVEAL and COMMIT.
Jacob/David/George,
We typically add a distinguishing value to hashes and signatures in prop224 -
can/should we do that for the shared random proposal as well?
It would look like:
RN = 255-bit random number
REVEAL_VALUE = H("derive-reveal" | RN)
COMMIT_VALUE = H("derive-commit" | REVEAL_VALUE)
Tim
Tim Wilson-Brown (teor)
teor2345 at gmail dot com
PGP 968F094B
teor at blah dot im
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