libsparkcrypto is a formally verified implementation of several widely used cryptographic algorithms using the SPARK 2014 programming language and toolset ¹. For the complete library proofs of the absence of run-time errors like type range violations, division by zero and numerical overflows are available. Some of its subprograms include proofs of partial correctness.

The distribution contains test cases for all implemented algorithms and a benchmark to compare its performance with the OpenSSL library².

libsparkcrypto is released under the simplified BSD license:

Redistribution  and  use  in  source  and  binary  forms,  with  or  without
modification, are permitted provided that the following conditions are met:

   * Redistributions of source code must retain the above copyright notice,
     this list of conditions and the following disclaimer.

   * Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.

   * Neither the name of the  nor the names of its contributors may be used
     to endorse or promote products derived from this software without
     specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE  COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY  EXPRESS OR IMPLIED WARRANTIES,  INCLUDING, BUT NOT LIMITED  TO, THE
IMPLIED WARRANTIES OF  MERCHANTABILITY AND FITNESS FOR  A PARTICULAR PURPOSE
ARE  DISCLAIMED. IN  NO EVENT  SHALL  THE COPYRIGHT  HOLDER OR  CONTRIBUTORS
BE  LIABLE FOR  ANY  DIRECT, INDIRECT,  INCIDENTAL,  SPECIAL, EXEMPLARY,  OR
CONSEQUENTIAL  DAMAGES  (INCLUDING,  BUT  NOT  LIMITED  TO,  PROCUREMENT  OF
SUBSTITUTE GOODS  OR SERVICES; LOSS  OF USE,  DATA, OR PROFITS;  OR BUSINESS
INTERRUPTION)  HOWEVER CAUSED  AND ON  ANY THEORY  OF LIABILITY,  WHETHER IN
CONTRACT,  STRICT LIABILITY,  OR  TORT (INCLUDING  NEGLIGENCE OR  OTHERWISE)
ARISING IN ANY WAY  OUT OF THE USE OF THIS SOFTWARE, EVEN  IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

This version of libsparkcrypto implements the following cryptographic algorithms and modes:

• AES-128, AES-192, AES-256
• AES-CBC (all supported AES modes)
• SHA-1
• HMAC-SHA1
• SHA-256, SHA-384, SHA-512
• HMAC-SHA-256, HMAC-SHA-384, HMAC-SHA-512
• PRF-HMAC-SHA-256, PRF-HMAC-SHA-384, PRF-HMAC-SHA-512
• RIPEMD-160
• HMAC-RIPEMD-160
• ECDSA, ECGDSA

The current development version of libsparkcrypto is available through its GIT ³ repository: https://github.com/Componolit/libsparkcrypto.git

A browsable version of the repository is also available here: https://github.com/Componolit/libsparkcrypto

To build and prove libsparkcrypto, the following tools are required:

• GNAT (recent Pro or FSF)
• SPARK 2014 (tested with Pro 19.0 and Community 2018)
• GNU make
• OpenSSL (for building the benchmark, tested with 1.1.1j)

The primary development environments of libsparkcrypto are Debian (x86_64) and Ubuntu (x86_64). Though the source and project files should be system independent, the Makefiles assume a UNIXish system (cygwin seems to work). Tools like mkdir, uname, tail and install must be present in the systems search path.

To build libsparkcrypto, change to the source directory and type:

$ make

You can install the library to <destination>, by typing:

$ make DESTDIR=<destination> install

libsparkcrypto was successfully built and tested on the following systems:

Please send bug reports and comments to Alexander Senier <[email protected]>.

Examples for using libsparkcrypto can be found in the tests subdirectory.

A user of the library has to provide a shadow for the package Interfaces providing a type definition for at least Unsigned_8, Unsigned_32 and Unsigned_64.

You are welcome to extend libsparkcrypto according to the terms of the simplified BSD license referenced above. Please obey the following rules when contributing changes back to the project:

• Make sure no undischarged VCs remain.
• Make sure the code compiles in both modes MODE=release and MODE=debug.
• Provide reference to documents and test cases for the parts you implemented.
• Make sure you successfully ran the test suite (make test).
• Try to stay consistent with the current style of the source.
• If feasible, implement a benchmark for your code.
• Create a pull request on GitHub

The Directory structure of libsparkcrypto is as follows:

The directories src/ada and src/shared have a sub-directory generic, which contains platform independent code. Furthermore, there are feature-specific directories like little_endian and architecture-specific directories like x86_64 which are included to proof and build steps as configured.

Configuration is performed automatically by the top-level Makefile and can be altered by passing the following variables to make:

• Thanks to Adrian-Ken Rüegsegger and Reto Buerki for hosting the project's GIT repository.
• Thanks to Adacore and Altran Praxis for review, comments and support with many tricky problems.