# Cryptol, version 2 This version of Cryptol is (C) 2013-2014 Galois, Inc., and distributed under a standard, three-clause BSD license. Please see the file LICENSE, distributed with this software, for specific terms and conditions. # What is Cryptol? The Cryptol specification language was designed by Galois for the NSA's Trusted Systems Research Group as a public standard for specifying cryptographic algorithms. A Cryptol reference specification can serve as the formal documentation for a cryptographic module. Unlike current specification mechanisms, Cryptol is fully executable, allowing designers to experiment with their programs incrementally as their designs evolve. This release is an interpreter for version 2 of the Cryptol language. The interpreter includes a `:check` command, which tests predicates written in Cryptol against randomly-generated test vectors (in the style of [QuickCheck](http://hackage.haskell.org/package/QuickCheck). There is also a `:prove` command, which calls out to SMT solvers, such as Yices, Z3, or CVC4, to prove predicates for all possible inputs. # Getting Cryptol Binaries Cryptol binaries for Mac OS X, Linux, and Windows are available from the GitHub [releases page](https://github.com/GaloisInc/cryptol/releases). Mac OS X and Linux binaries are distributed as a tarball which you can extract to a location of your choice. Windows binaries are distributed as an `.msi` installer package which places a shortcut to the Cryptol interpreter in the Start menu. ## Getting CVC4 Cryptol currently depends on the [CVC4 SMT solver](http://cvc4.cs.nyu.edu/) to solve constraints during typechecking, and as the default solver for the `:sat` and `:prove` commands. You can download CVC4 binaries for a variety of platforms from their [download page](http://cvc4.cs.nyu.edu/downloads/). # Building Cryptol From Source In addition to the binaries, the Cryptol source is available publicly on [GitHub](https://github.com/GaloisInc/cryptol). Cryptol builds and runs on various flavors of Linux, Mac OS X, and Windows. We regularly build and test it in the following environments: - Mac OS X 10.9 64-bit - CentOS 5 32/64-bit - CentOS 6 32/64-bit - Windows XP 32-bit ## Prerequisites Cryptol is developed using GHC 7.6.3 and cabal-install 1.18. While you can install these independently, the easiest way to get the correct versions is to: 1. Install [Haskell Platform 2013.2.0.0](http://www.haskell.org/platform/) **Mac Users**: the current version of the Haskell Platform has some incompatibilities with Mac OS X 10.9; it is easier to install GHC, cabal-install, alex, and happy from [MacPorts](https://www.macports.org/) or [Homebrew](http://brew.sh/). 1. Run `cabal update` 1. Run `cabal install cabal-install` 1. Add cabal-install's binary path to your `PATH` variable (usually `~/.cabal/bin`) Some supporting non-Haskell libraries are required to build Cryptol. Most should already be present for your operating system, but you may need to install the following: - [The GNU Multiple Precision Arithmetic Library (GMP)](https://gmplib.org/) - [ncurses](https://www.gnu.org/software/ncurses/) You'll also need [CVC4](#getting-cvc4) installed when running Cryptol. ## Building Cryptol From the Cryptol source directory, run: make This will build Cryptol in place. From there, there are additional targets: - `make test`: run the regression test suite - `make docs`: build the Cryptol documentation (requires [pandoc](http://johnmacfarlane.net/pandoc/) and [TeX Live](https://www.tug.org/texlive/)) - `make tarball`: build a tarball with a relocatable Cryptol binary and documentation - `make dist`: build a platform-specific distribution. On all platforms except Windows, this is currently equivalent to `make tarball`. On Windows, this will build an `.msi` package using [WiX Toolset 3.7](http://wixtoolset.org/), which must be installed separately. ## Installing Cryptol Aside from the `docs` target, these will leave you with a Cryptol binary at `.cabal-sandbox/bin/cryptol` in your source directory. You can either use that binary directly, or use the results of `tarball` or `dist` to install Cryptol in a location of your choice. # Checking your Installation Run Cryptol, and at the prompt type: Cryptol> :prove True If Cryptol responds Q.E.D. then Cryptol is installed correctly. If it prints something like *** An error occurred. *** Unable to locate executable for cvc4 *** Executable specified: "cvc4" then make sure you've installed [CVC4](#getting-cvc4), and that the binary is on your `PATH`. # Contributing We believe that anyone who uses Cryptol is making an important contribution toward making Cryptol a better tool. There are many ways to get involved. ## Users If you write Cryptol programs that you think would benefit the community, fork the GitHub repository, and add them to the `examples/contrib` directory and submit a pull request. We host a Cryptol mailing list, which you can [join here](http://community.galois.com/mailman/listinfo/cryptol-users). If you run into a bug in Cryptol, if something doesn't make sense in the documentation, if you think something could be better, or if you just have a cool use of Cryptol that you'd like to share with us, use the issues page on [GitHub](https://github.com/GaloisInc/cryptol), or send email to . ## Developers If you plan to do development work on the Cryptol interpreter, please make a fork of the GitHub repository and send along pull requests. This makes it easier for us to track development and to incorprate your changes. ### Repository Structure - `/cryptol`: Haskell sources for the front-end `cryptol` executable and read-eval-print loop - `/docs`: LaTeX and Markdown sources for the Cryptol documentation - `/examples`: Cryptol sources implementing several interesting algorithms - `/lib`: Cryptol standard library sources - `/notebook`: Experimental Cryptol IPython Notebook implementation - `/sbv`: Haskell sources for the `sbv` library, derived from Levent Erkok's [`sbv` library](http://leventerkok.github.io/sbv/) (see `/sbv/LICENSE`) - `/src`: Haskell sources for the `cryptol` library (the bulk of the implementation) - `/tests`: Haskell sources for the Cryptol regression test suite, as well as the Cryptol sources and expected outputs that comprise that suite # Where to Look Next The `docs` directory of the installation package contains an introductory book, the `examples` directory contains a number of algorithms specified in Cryptol. If you are familiar with version 1 of Cryptol, you should read the `Version2Changes` document in the `docs` directory. Cryptol is still under active development at Galois. We are also building tools that consume both Cryptol specifications and implementations in (for example) C or Java, and can (with some amount of work) allow you to verify that an implementation meets its specification. Email us at if you're interested in these capabilities. # Thanks! We hope that Cryptol is useful as a tool for educators and students, commercial and open source authors of cryptographic implementations, and by cryptographers to * specify cryptographic algorithms * check or prove properties of algorithms * generate test vectors for testing implementations * experiment with new algorithms ## Acknowledgements Cryptol has been under development for over a decade with many people contributing to its design and implementation. Those people include (but are not limited to) Aaron Tomb, Adam Wick, Brian Huffman, Matt Sottile, Adam Foltzer, Joe Hendrix, Trevor Elliott, Lee Pike, Mark Tullsen, David Lazar, Joel Stanley, Jeff Lewis, Andy Gill, Edward Yang, Ledah Casburn, Jim Teisher, Sigbjørn Finne, Mark Shields, Philip Weaver, Magnus Carlsson, Fergus Henderson, Joe Hurd, Thomas Nordin, John Matthews and Sally Browning. In addition, much of the work on Cryptol has been funded by, and lots of design input was provided by the team at the [NSA's Trusted Systems Research Group](http://www.nsa.gov/research/ia_research/), including Brad Martin, Frank Taylor and Sean Weaver.