tczajka

4 ms·

1.
by tczajka 3y ago
As alright2565 already mentioned, sticking rand() in there doesn't add any benefit over a key + counter. Without rand() it would be something like SHA3-CTR -- it's not standardized which is why I would prefer ChaCha20, but it has
2.
by tczajka 3y ago
Isn't it also similarly conceivable that if you write a predictable PRNG sequence such the outputs of Mersenne Twister you could also potentially extract patterns? Mersenne Twister is essentially as predictable as a short cycle.
3.
by tczajka 3y ago
If this is sufficient, then this matches what I said in the article. I wrote that if you don't care about what numbers you get, don't bother with xoroshiro or Mersenne Twister, just use https://xkcd.com/221/ .
4.
by tczajka 3y ago
If a predictable PRNG is sufficient for wiping disks, why do we care that the data is random at all? How about writing 0, 1, 2, ..., 255, 0, 1, 2, ... to consecutive bytes? Or -- generate 1 kb of good quality random data, and write the same
5.
by tczajka 3y ago
I can just about believe that this kind of scenario might be a very rare exception where the performance difference is relevant and you might want to do something else. Still, color me skeptical. "In simple enough scenes"? OK pe
6.
by tczajka 3y ago
It's not true that I cherry-picked a slow PRNG for my 7 GB/s number. In fact I selected the second-fastest PRNG on that page (because it's popular)! The fastest one is 8 GB/s. PCG32 is 3 GB/s. Your 4000x factor spee
7.
Need a PRNG? Use a CSPRNG(sortingsearching.com)
74 points by tczajka 3y ago|99 comments