On Thu, Sep 16, 2021 at 8:42 PM austin clifton <austin.clif...@otoy.com> wrote: > > Hi all, > > I have an issue which I believe may be a bug. I followed the instructions > from the "Bug Report" page on the cryptopp wiki and all tests in cryptest.exe > are passing, so figured I should post here first and make sure it isn't a > build related issue. > > I built cryptopp 8.5.0 as a static library, x64 multi-threaded debug (\MTd) > using Visual Studio 2019 v16.10.0, on Windows 10 Pro v10.0.19043, using the > .sln file provided with the cryptopp source code. > > I used two different machines for this test. One is the machine I built the > cryptopp library with. Both are running the same version of Windows 10. One > machine has a Ryzen 3700X, the other has an i7-990X. The Ryzen supports AVX, > the i7 does not. > > I am VERY rarely finding that files encrypted with the chacha cipher by these > two machines have differing sha256 hashes. If I do a hex diff against the > files, there is a single flipped bit at 0x1EBB4 (0xD8 vs 0xD9). > > I am able to reproduce this consistently with a specific key, nonce, and > input file, after test encrypting ~50GB of 1MB garbage files on each machine. > > If I disable AVX when building cryptlib by defining CRYPTOPP_DISABLE_AVX and > CRYPTOPP_DISABLE_AVX2, the machine with the Ryzen will encrypt the file the > same as the i7. > > Source code for a minimal reproducible example is here: > https://github.com/austin-clifton/cryptopp-chacha-asm-test/blob/main/src/main.cpp#L208 > > That repository includes a ready-to-build test case with Visual Studio, minus > a built cryptlib.lib which should be added to libs/debug/ before building.
Ugh, I dislike these reports. I've seen a similar problem on a Ryzen with SHA. It is GCC67, which is Ryzen 5 2400G, at https://cfarm.tetaneutral.net/machines/list/. One self test failed but no others. The one test that failed is one with a very long input string. I believe it is/was the last test at https://github.com/weidai11/cryptopp/blob/master/TestVectors/sha2_256_fips_180.txt. I am thinking the problem is with either GCC's AMD target code or the Ryzen CPU itself. The problem eventually cleared itself. With that said, can you give Master a try? We cleared a bug at https://github.com/weidai11/cryptopp/issues/1010 that may affect GCC's code generation. It was a bug related to GCC alias violations, and GCC would remove code on occasion. Something else to try... Update the firmware on the machine in case a firmware or microcode update addressed the issue. 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/CAH8yC8nz5iMi5JbVVDBZQM%3D-uYZe_C8EEq7S%2B62V2bSqQg3dwQ%40mail.gmail.com.
