rhythmbox should be ported to use NSS library for cryptography.
See the tracking bug for details and links on how it could be done.
rhythmbox doesn't use gnutls or another crypto library. You're probably looking
at what gnome-vfs pulls in.
Some plugins contain its own MD5 implementation. If it is not used for security
relevant purposes then it doesn't matter to the CryptoConsolidation project though.
Filed bugs upstream: