MD5 hash

[roman-khimov]

Is your feature request related to a problem? Please describe.

I'm always frustrated when I look at nspcc-dev/neofs-s3-gw#1053.

Describe the solution you'd like

I see no other way to solve it but to add yet another hash field to NeoFS objects (nspcc-dev/neofs-s3-gw#1053 (comment)). Yeah, that's MD5. In 2025.

Describe alternatives you've considered

Unknown.

[roman-khimov]

Consider https://docs.aws.amazon.com/AmazonS3/latest/userguide/checking-object-integrity.html here as well. While technically we can add five more fields to the object structure this would obviously make it a bloody mess of hashes and impact metabase as well. Instead we can consider either:

• adding an aux_hashes field with an array of hashes (and deprecate homomorphic_hash? after *: deprecate audit and storage groups #339 it's not very useful); container attributes can then regulate which hashes are calculated and stored
• adding a __NEOFS__AUX_HASHES user-defined attribute (and using internal S3 slicer) that would allowed to be different for first and last object parent (big) headers, functionally similar to the above one, but application-specific

This would make it impossible to search for something with a particular aux hash, but practically sha256 index from the respective field should be sufficient.

Other ideas are welcome.