On this page you can download the source code of the CASPA tool as well as a selection of protocols from the AVISPA library already translated into the prot format.
The source package contains the OCaml sources of the tool and the if2prot compiler. In order to compile the programs, you need an installed version of OCaml. The gui needs in addition the TK toolkit installed and OCaml compiled with tk bindings. Finally, the visualization of graphs requires Graphviz. For further instructions on how to compile and use CASPA please take a look at the manual page.