btw2, UUID actually uses MD5 and SHA, but on a smaller input than full

file contents.

Pharo implements version 4, which uses purely random bits; not MD5/SHA/MAC.

��

btw3, I love turtles all the way down, but given that crypto
algorithms are CPU bound and Pharo will be single-CPU for some time,
it might be pragmatic to have the crypto primitives to thread onto a
separate CPU, and maybe take advantage of hardware acceleration.�� Call
it SHAxExternal...
https://software.intel.com/en-us/articles/intel-sha-extensions

There's an advantage of using UUIDs, because if you have larger files, hashing them might take a considerable amount of CPU time and disk I/O.

But having it content-based is also an advantage, because it can be created independently (and verifiably).

Peter