A diff utility which works with binary fileshttp://xdelta.org/
Xdelta3 is a set of tools designed to compute changes between
binary files. These changes (delta files) are similar to the output of the
"diff" program, in that they may be used to store and transmit only the
changes between files. The "delta files" that Xdelta3 manages are
stored in RFC3284 (VCDIFF) format.