https://github.com/ArchiveTeam/grab-site might be helpful. I'm a fan of the ability to create WARC archives from a target, uploard the WARC files to object storage (whether that is IA, S3, Backblaze B2, etc), and then keep them in cold storage or serve them up via HTTPS or a torrent (mutable, preferred). The Internet Archive serves a torrent file for every item they host; one can do the same with WARC archives to ena…
I recommend Browsertrix for WARC creation, I think they are the best currently available for WARC/WACZ. ArchiveBox is also gearing up to support real cryptographic signing of archives using https://tlsnotary.org/ in an upcoming plugin. (in a way that actually solves the TLS non-repudation issue, which traditional "signing a WARC" does not, more info: https://www.ndss-symposium.org/wp-content/uploads/2018/02/nd... )
That's a really interesting point. The gut reaction is "why are we wasting time on adding a nice-to-have such as a very fancy cousin of the MD5 checksum when the real meat of the time & effort is maximizing data download and scale"
But then, then go read the book 1984 and it may become clear the importance of ensuring the data is unchanged down the road.
But if this is a hedge against hypothetical future 1984 world, one would have to ask - what if the only file available has the wrong md5sum? Because then most people would say, "welp, something is better than nothing" and that's it. Perhaps something that might provide additional information about what/how/where something was changed in more detail.