This uses the stdlib's method of creating a tempfile in our write
file atomimc method, with a few modifications. We use a 64 bit number
rather than 32 bit, and therefore a corresponding LCG. This is to
reduce collision probability. (Note we currently used 32 bytes previously,
so this is likely a concern)
We handle reseeding the LCG in such a way that multiple threads are
even less likely to reuse the same seed.
This now makes bit array functions which take in a second bit array, thread
safe. Previously there was a warning on bitarray.Update to be lock the
second parameter externally if thread safety wasrequired.
This was not done within the codebase, so it was fine to change here.
Closes#2080
Currently the top level directory contains basically all of the code
for the crypto package. This PR moves the crypto code into submodules
in a similar manner to what `golang/x/crypto` does. This improves code
organization.
Ref discussion: https://github.com/tendermint/tendermint/pull/1966Closes#1956
We were computing these functions incorrectly.
I'm not sure what distribution these numbers are, but it isn't the
normal exponential distribution. (We're making the probability of
getting a number of a particular bitlength equal, but the number in
that bitlength thats gets chosen is uniformly chosen)
We weren't using these functions anywhere in our codebase, and they
had a nomenclature error. (There aren't exponentially distributed
integers, instead they would be geometrically distributed)
The godocs fell out of sync with the code here. Additionally we had
warning that these randomness functions weren't for cryptographic
use on every function. However these warnings are confusing, since
there was no implication that they would be secure there, and a
single warning on the actual Rand type would suffice. (This is what
is done in golang's math/rand godoc)
Additionally we indicated that rand.Bytes() was reading OS randomness
but in fact that had been changed.
This commit switches all usage of math/rand to cmn's rand. The only
exceptions are within the random file itself, the tools package, and the
crypto package. In tools you don't want it to lock between the go-routines.
The crypto package doesn't use it so the crypto package have no other
dependencies within tendermint/tendermint for easier portability.
Crypto/rand usage is unadjusted.
Closes#1343
Dev Ojha
ValarDragon
Silas Davis
Zach Ramsay
Ethan Buchman