4 ms·

I wish that issue would also link to the rebuttal: https://www.pcg-random.org/posts/on-vignas-pcg-critique.html https://www.pcg-random.org/posts/on-vignas-pcg-c

I wish that issue would also link to the rebuttal: https://www.pcg-random.org/posts/on-vignas-pcg-critique.html https://www.pcg-random.org/posts/on-vignas-pcg-critique.html

tptacek 5y ago
Do you find that rebuttal persuasive? For someone who doesn't care at all about anyone's "tone", and just wants to know what the hell is going on with these constructions, I didn't find much there.
- omoikane 5y ago
  My reading of both: - Vigna claims small differences in internal states don't have avalanche effects, and the rebuttal says those small differences in internal states don't occur normally, not with the proper seeding steps. - Vigna claims to be able to predict one particular variant of PCG, and the rebuttal said that that was one of the weaker variants that specifically has "insecure" in the name. It's persuasive to me in suggesting that Vigna's claims are perhaps not that clear cut. I am not an expert in PRNG and I wouldn't say this makes PCG win over Xorshiro or not, I just think it's unfortunate that the issue above linked only one side of the argument, especially since I find the other side more pleasant to read.
ttybird2 5y ago
https://www.pcg-random.org/ https://www.pcg-random.org/ PCG's statistical quality is "excellent" but chacha20's just "good"?
- loeg 5y ago
  It is a bit odd. I think the PCG authors are talking about reduced-round variants below 8[1] re: statistical quality. I agree it doesn't belong in a row labeled "ChaCha20." It seems obvious that chacha below 4 rounds is total garbage[2] but I don't know much about 4-7 rounds. The Too Much Crypto guy likes 8 rounds for cryptographic purposes. [1]: https://www.pcg-random.org/other-rngs.html#id7 https://www.pcg-random.org/other-rngs.html#id7 [2]: https://cr.yp.to/snuffle/diffusion.html https://cr.yp.to/snuffle/diffusion.html

4 ms·

I wish that issue would also link to the rebuttal: https://www.pcg-random.org/posts/on-vignas-pcg-critique.html https://www.pcg-random.org/posts/on-vignas-pcg-c

by omoikane 5y ago

I wish that issue would also link to the rebuttal: https://www.pcg-random.org/posts/on-vignas-pcg-critique.html https://www.pcg-random.org/posts/on-vignas-pcg-critique.html

tptacek 5y ago
Do you find that rebuttal persuasive? For someone who doesn't care at all about anyone's "tone", and just wants to know what the hell is going on with these constructions, I didn't find much there.
- omoikane 5y ago
  My reading of both: - Vigna claims small differences in internal states don't have avalanche effects, and the rebuttal says those small differences in internal states don't occur normally, not with the proper seeding steps. - Vigna claims to be able to predict one particular variant of PCG, and the rebuttal said that that was one of the weaker variants that specifically has "insecure" in the name. It's persuasive to me in suggesting that Vigna's claims are perhaps not that clear cut. I am not an expert in PRNG and I wouldn't say this makes PCG win over Xorshiro or not, I just think it's unfortunate that the issue above linked only one side of the argument, especially since I find the other side more pleasant to read.
ttybird2 5y ago
https://www.pcg-random.org/ https://www.pcg-random.org/ PCG's statistical quality is "excellent" but chacha20's just "good"?
- loeg 5y ago
  It is a bit odd. I think the PCG authors are talking about reduced-round variants below 8[1] re: statistical quality. I agree it doesn't belong in a row labeled "ChaCha20." It seems obvious that chacha below 4 rounds is total garbage[2] but I don't know much about 4-7 rounds. The Too Much Crypto guy likes 8 rounds for cryptographic purposes. [1]: https://www.pcg-random.org/other-rngs.html#id7 https://www.pcg-random.org/other-rngs.html#id7 [2]: https://cr.yp.to/snuffle/diffusion.html https://cr.yp.to/snuffle/diffusion.html