On Fri, Sep 17, 2021 at 2:31 PM austin clifton <austin.clif...@otoy.com> wrote: > > Hey Jeff, thanks for the fast response! > > Yes, the encrypted sha from your AMD CPUs matches what I get on my Ryzen 7 > 3700X. > > The encrypted sha from the i7 is > 8F16077454F8477594CAD4304126B0A6F30C8C4D2536E2441FFFD320656E1DF1. That's also > the sha I get if I disable AVX on my Ryzen when compiling cryptopp. > > I'm not sure which sha is "correct" but we are seeing the same behavior > across the AMD CPUs. Would it make sense to disable assembly altogether to > get a reference encrypted sha256?
Yes, that is what I usually do when I need a reference. I add -DCRYPTOPP_DISABLE_ASM to CXXFLAGS. That removes all inline assembly and intrinsics. In the case of ChaCha there is another option for a reference. You can use Bernstein's reference implementation. I use the author's implementation for test vectors, when available. I keep them stashed away at https://github.com/noloader/cryptopp-test. Note that Bernstein's ChaCah and the IETF's ChaCha are slightly different. Bernstein uses a 64-bit counter that starts at 0 and cannot wrap. IETF uses a 32-bit counter that can wrap. The IETF never specified what to do when wrap occurs. > We are seeing the same behavior from MSVC and GCC compilers. I can try master > with GCC here too but sounds like that fix is unrelated? Yeah, I think that is an issue with the CPU, not the compiler. > I'll try to glean more useful data from logs I have here. We distribute > encrypted assets to lots of machines (all running Windows) but I have to dig > around some. The guy to ask is Agner Fog, https://www.agner.org. I'm not sure whether he runs a mailing list. Jeff -- You received this message because you are subscribed to the Google Groups "Crypto++ Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to cryptopp-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/cryptopp-users/CAH8yC8%3DH%2BXwUP6XUyaVRGC%3DSC91PfBDwPncC33YvoySihUsXzQ%40mail.gmail.com.
