Last modified 5 years ago Last modified on 04/10/12 16:40:24


Expi2Java is an extensible code generator for cryptographic protocols. It takes protocol specifications written in an extensible variant of the Spi calculus, configurations that provide the low-level information needed for code generation and produces interoperable Java code. The main features of Expi2Java are:

  • High customizability and extensibility
    • User-defined types, cryptographic primitives and low-level configurations
    • User-provided implementation classes
    • Code generation using code templates
  • An expressive type system prevents incorrect use of crypto primitives and configurations
    • The type-checker performs type inference, which decreases the annotation burden on the user
    • The type-checker catches errors early and provides helpful error messages
    • When type-checking the specification succeeds the tool is guaranteed to generate a well-typed Java program (modulo implementation bugs and bad customizations)
  • Input language compatible with ProVerif protocol verifier
  • Interoperable generated code
    • Generated implementation uses Java cryptographic providers
    • Most common cryptographic primitives and data types are supported out of the box
    • Full control over the low-level data format
    • As a case study, we have generated an interoperable implementation of TLS v1.0 client and server from a protocol model verified with ProVerif
  • Free software (GPL v3) developed in the open
  • Well-documented (see User Manual and Code Generation Tutorial)
  • New: Symbolic crypto + networking library
    • Abstracts crypto primitives as symbolic terms and networking as pi-calculus-like channels
    • Useful for local testing and debugging, as well as for our proofs
    • Concrete and symbolic libraries can be used interchangeably with all provided examples
  • New: Mechanized formalization and proofs in the Coq proof assistant





Implementation by Alex Busenius. GNU GPL, Version 3

  • Expi2Java 1.6, 11.05.2011 [8.8 MiB, SHA1: 164ce45c8121bdac9adcfc88e54ec12e1d4cc11c]

Formalization by Alex Busenius. GNU LGPL, Version 3


Expi2Java originated as an extension of the Spi2Java framework by Davide Pozza, Alfredo Pironti, Riccardo Sisto and Luca Durante, and still uses a little of the Spi2Java code.

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