[RFC PATCH] Add SHA1 support

[Dimitrios Apostolou]

On Thursday, February 20, 2020 10:34:53 PM CET, Sebastian Andrzej Siewior 
via rsync wrote:
>
> I'm still not sure if rsync requires a cryptographic hash _or_ if a
> strong hash like xxHash64 would be just fine for the job.

I'm fairly sure the hash should *not* be easy to spoof, so I'd say a 
cryptographic hash is needed.

As an example, if a file is replaced by a file of the same size and same 
hash,
rsync (if -c is in use) will consider the file is the same, and avoid 
copying it.


Dimitris