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Build Status

Fiat-Crypto: Synthesizing Correct-by-Construction Code for Cryptographic Primitives

Build Requirements

This repository requires:

  • To build the proofs and almost-C-like outputs: Coq 8.7 or Coq 8.8 (tested with 8.7.2, 8.8.0)

If you checked out this repository via git, you should run

git submodule update --init --recursive

To build (if your COQPATH variable is empty):

make

To build:

export COQPATH="$(pwd)/coqprime${COQPATH:+:}$COQPATH"
make

You may get non-fatal errors such as make: execvp: /bin/sh: Argument list too long; this is an artifact of the old pipeline and is a bug in Coq that will prevent make install from succeeding, but will not impact the build itself.

New Pipeline

The new pipeline (nearly finished) generates binaries that take in arguments on the command line and print out C code on stdout.

A collection of C files can be made with

make c-files

The C files will appear in the top-level directory.

The binaries generating these C files can be made with

make standalone

or make standalone-haskell or make standalone-ocaml for binaries generated with just one compiler.

The binaries are located in

src/Experiments/NewPipeline/ExtractionOCaml/

or

src/Experiments/NewPipeline/ExtractionHaskell/

The binaries are:

  • saturated_solinas
  • unsaturated_solinas
  • word_by_word_montgomery

Passing no arguments, or passing -h or --help (or any other invalid arguments) will result in a usage message being printed. These binaries output C code on stdout.

Here are some examples of ways to invoke the binaries (from the directories that they live in):

# Generate code for 2^255-19
./unsaturated_solinas '25519' '5' '2^255' '1,19' '64' carry_mul carry_square carry_scmul121666 carry add sub opp selectznz to_bytes from_bytes > curve25519_64.c
./unsaturated_solinas '25519' '10' '2^255' '1,19' '32' carry_mul carry_square carry_scmul121666 carry add sub opp selectznz to_bytes from_bytes > curve25519_32.c

# Generate code for NIST-P256 (2^256 - 2^224 + 2^192 + 2^96 - 1)
./word_by_word_montgomery 'p256' '2^256' '2^224,1;2^192,-1;2^96,-1;1,1' '32' > p256_32.c
./word_by_word_montgomery 'p256' '2^256' '2^224,1;2^192,-1;2^96,-1;1,1' '64' > p256_64.c

Old Pipeline

To build a representative subset, instead of make, run

    make selected-specific-display non-specific

The core library (target nonautogenerated-specific-display non-specific) is expected to build within about one hour (in serial, on a particularly fast machine), within about 3.5--4 GB of RAM, plus an additional 1-5 minutes to run coqdep on all of our files. Of the additional curves, 90% finish within 5 minutes per file, and 99% finish within 15 minutes per file (though some take upwards of 50 GB of RAM). These 99% of curves together take about 60 hours.

  • To build the C outputs: Python (2 or 3)

To build:

    make c

or, for a representative subset,

    make selected-c
  • To build and run the binaries, gcc (7.1.2; or 7.1.1 with -fno-peephole2) or clang of a new enough version to support the appropriate compiler intrinsics.

To build and run:

    make test bench

or, for a representative subset,

    make selected-test selected-bench

Exploring the code

Push-button synthesis

To add a new prime, add a new line to primes.txt with your prime. Then run

    ./generate_parameters.py; ./src/Specific/CurveParameters/remake_curves.sh

You will see a bunch of lines starting with git add; any .v files that show up in these lines must be added to _CoqProject. (If you are working in the git repository, you may simply run the git add lines, and then run make update-_CoqProject.) Note that the directory structure involves a textual representation of your prime, call it ${REPRESENTATION_OF_YOUR_PRIME}. To build, you can run

    make src/Specific/{montgomery,solinas}{32,64}_${REPRESENTATION_OF_YOUR_PRIME}/fibe

This will build all the necessary .vo and .c files, as well as the fibe binary, which is automatically run when you make bench or make test.

Curve Correctness Theorems

Specifications live in src/Spec, e.g., src/Spec/Ed25519.v. Some selected cuve-level proofs live in

Arithmetic Core

Generic mathematical optimization strategies live in src/Arithmetic. Good examples include

Demo of Synthesis

The idea of the synthesis process is demoed in src/Demo.v.

Actual Synthesis

The curve-specific synthesis framework lives in src/Specific/Framework.

Example Output

The c output lives in the various subfolders of src/Specific. For example, C-like code for X25519 multiplication on 64-bit machines lives in src/Specific/X25519/C64/femulDisplay.log, which is generated from src/Specific/X25519/C64/femulDisplay.v, which in turn uses synthesis run in src/Specific/X25519/C64/femul.v. The c target turns this into src/Specific/X25519/C64/femul.c.

Footnotes

¹ This magic comes in the form of calls to transparent_abstract, packaged up in some tactics in src/Util/Tactics/CacheTerm.v.