Adding a find jar by checksum functionality to the REST api

In 1.3.x versions, an applet gave us the possibility to know if a jar (on our local disk) was already in the repo, using the checksum files.

I would like to have this useful functionality back in v2.x,, but through a REST service : I provide a checksum code, and I get the list of artifacts that correspond to this checksum.

Thanks !