@hackage cpsa4.4.3

CPSA4: Cryptographic Protocol Shapes Analyzer Version 4

The Cryptographic Protocol Shapes Analyzer (CPSA) attempts to enumerate all essentially different executions possible for a cryptographic protocol. We call them the shapes of the protocol. Naturally occurring protocols have only finitely many, indeed very few shapes. Authentication and secrecy properties are easy to determine from them, as are attacks and anomalies.

For each input problem, the CPSA program is given some initial behavior, and it discovers what shapes are compatible with it. Normally, the initial behavior is from the point of view of one participant. The analysis reveals what the other participants must have done, given the participant's view. The search is complete, i.e. we proved every shape can in fact be found in a finite number of steps, relative to a procedural semantics of protocol roles.

CPSA4 is based on a refactoring of CPSA2. It is distinct from CPSA3. It is used to experiment with new features. It is where a different security goal language, the strand-oriented language described in "Deducing Security Goals From Shape Analysis Sentences" https://arxiv.org/abs/1204.0480, was first implemented. The size of the formulas expressed in the strand-oriented language is typically smaller than the ones produced using the previous node-oriented language, an important property when the formulas are used to interact with theorem provers and proof assistants.

CPSA4 provides rules and facts. Rules are associated with protocols, and facts are associated with skeletons. A rule is a geometric formula that is used as a rewrite rule, and a fact is a named relation between values.

CPSA4 provides channels. Channels are designed to model confidential and authenticated communication channels.

This program has been built and tested using the Haskell miminal installer and Haskell Platform. These are available from http://haskell.org or from an operating system specific source. The name of the Linux package is usually haskell-platform. If you have problems installing Haskell, try using Haskell Stack, and issue the commands "stack init; stack build, stack install".

INSTALLING FROM A TARBALL

Build and install with:

$ cabal build $ cabal install --overwrite-policy=always

DOCUMENTATION LOCATION

To find the directory containing documentation and samples, type:

$ cpsa4 -h

QUICK START (Linux)

: To analyze a protocol you have put in prob.scm type: $ cpsa4 -o prob.txt prob.scm $ cpsa4graph -o prob.xhtml prob.txt $ firefox -remote "openFile(pwd/prob.xhtml)"

QUICK START (Mac)

: To analyze a protocol you have put in prob.scm type: $ cpsa4 -o prob.txt prob.scm $ cpsa4graph -o prob.xhtml prob.txt $ open prob.xhtml

QUICK START (Windows)

With Cygwin or MinGW, the installation is similar to the Linux install. The software has been tested on a Windows system on which neither MinGW or Cygwin has been installed. Install Haskell Platform Core and then run:

C:...> cabal update C:...> cabal install parallel C:...> cabal build C:...> cabal install --overwrite-policy=always

Documentation and samples are in the directory given by C:...> cpsa4 -h

The installed programs can be run from the command prompt or via a batch file. Alternatively, copy doc/Make4.hs into the directory containing your CPSA problem statements, and load it into a Haskell interpreter. Read the source for usage instructions.

MAKEFILE

To start your own project, create a fresh directory and then type:

$ cpsa4init

This will create a Makefile that automates the analysis process. For Windows, it will also create Make4.hs, a cpsa build script written in Haskell.

PARALLELISM

CPSA is built so it can make use of multiple processors. To make use of more than one processor, start CPSA with the -N runtime flag, as in "+RTS -N -RTS". The GHC documentation describes the -N option in detail.

DOCUMENTATION

The starting point for CPSA documentation doc/index.html. Most users should read it and skip the rest of this section. The documentation includes a user guide as an XHTML document, and three LaTeX documents. The CPSA Primer provides the background required to make effective use of the CPSA tool collection. For those interested in the implementation, The CPSA Theory contains a high-level description of the algorithm and the current state of the effort to show that when program terminates, it produces a description of every possible execution of the protocol consistent with the initial point-of-view skeleton. The CPSA Specification formally describes the implemented algorithm as a term reduction system. The CPSA Design describes implementation details and assumes The CPSA Specification has been read. The CPSA Design should be read if one is interested in reading the Haskell source for the tool collection.

TEST SUITE

Cabal currently fails to preserve permissions correctly. To fix this problem, type:

$ /bin/sh fixperms

: To run the test suite type: $ ./cpsatst

Tests with the .scm extension are expected to complete without error, tests with the .lsp extension are expected to fail, and tests with the .lisp extension are not run. New users should read tst/README, and then browse the files it suggests while reading CPSA documentation.

ADDITIONAL PROGRAMS

The src directory of the source distributions includes programs written in Scheme, Prolog, Elisp, and OCamlq for performing tasks. Use them as templates for your special purpose CPSA analysis and transformation needs. Also, when given the --json option, the CPSA pretty printer cpsapp will transform CPSA S-expressions into JavaScript Object Notation (JSON).

On Linux, the GHC runtime can request so much memory that thrashing results. The script in src/ghcmemlimit sets an environment variable that limits memory to the amount of free and reclaimable memory on your machine.

KNOWN BUGS

Variable separation in generalization fails to separate variables in terms of the form (ltk a a).