RabbitSign is a free implementation of TI's application signing system for the TI-73/83+/84+ calculators.

It handles binary, sorted and unsorted hex, and GraphLink files, automatically detects keys, checks the validity of important header fields, can validate and re-sign previously signed apps, accepts all valid keys, is highly portable, has no stupid limitations on file names, application lengths, or header fields and is faster by an order of magnitude than TI's software.