I appreciate all suggestions and opinions mentioned. But let me clarify why I made those design choses a bit more.
- Yes, it is faster because OpenSSL uses specific assembly instructions of modern CPUs. - I believe that this optimization should *not* be done in APR (apr-util to be more specific). Most of its users don't want it to be crazy fast. They would most probably choose a more portable, simple, and lightweight implementation instead. Subversion, on the other hand, will generally work faster as checksumming improves. - There is a public structure for checksum context data in APR so this might be problematic to adapt a different implementation. - Httpd barely uses it and it's never critical to the overall performance part. I could find that only mod_lua and password authentication support uses SHA1 from APR. It's not an optimization whenever this code is called once a decade for like <20 bytes of data. - I discovered a much more convenient cryptography library (AWS-LC [1]). It's basically a fork of OpenSSL, but with simplified everything. We might make an interface for it as well. - It's a great idea to "steal" optimized hash implementation, so we'd get that performance boost without requiring any third-party libraries. I think AWS-LC would be more suitable for this purpose because it bundles pre-generated assembly sources whereas OpenSSL needs perl for that. Therefore, I suggest we move towards optimizing hashes in Subversion specifically. I don't like OpenSSL either, but it's a good enough direction to start. [1] https://github.com/aws/aws-lc -- Timofei Zhakov
