nix-linux-sgx

Nix derivations for the C++ Linux SGX SDK, IPP-Crypto library, and Architectural Enclaves.

This work is of particular interest for enclave applications that rely on the C++ Linux SGX SDK and wish to have reproducible enclave builds. Reproducible enclave builds can be of vital importance in remote attestation, and also for sealing data with an enclave policy.

This work originated from working with the Linux SGX reproducible environment found at https://github.com/intel/linux-sgx/tree/master/linux/reproducibility. Enclave developers and builders can write nix derivations for their enclaves and specify the SGX SDK as a dependency just like any other dependency.

Install

We hope to soon have the SGX SDK nix package merged into the nixpkgs repository (see draft pull request at NixOS/nixpkgs#126990) . Until then you can install the SGX SDK nix package from cachix like so:

nix-env -iA sgxsdk -f https://github.com/initc3/nix-linux-sgx/tarball/main \
    --substituters https://initc3.cachix.org \
    --trusted-public-keys initc3.cachix.org-1:tt+5+CggCBEur43PcFgrkNxdlOFBnoB01aLe6y6yMcA=

If you are writing a nix derivation, you can use the following approach, using niv:

niv add initc3/nix-linux-sgx --name sgx

Then you can write your nix derivation like so:

let
  sources = import ./nix/sources.nix;
  pkgs = import sources.nixpkgs { };
  sgx = import sources.sgx;
in
pkgs.stdenv.mkDerivation {
  name = "sgx-myapp";
  src = pkgs.fetchFromGitHub {
    owner = "myrepo";
    repo = "sgx-myapp";
    rev = "a1...";
    sha256 = "b2...";
  };
  preConfigure = ''
    export SGX_SDK=${sgx.sgxsdk}/sgxsdk
    export PATH=$PATH:$SGX_SDK/bin:$SGX_SDK/bin/x64
    export PKG_CONFIG_PATH=$SGX_SDK/pkgconfig
    export LD_LIBRARY_PATH=$SGX_SDK/sdk_libs
    '';
  buildInputs = with pkgs; [
    sgx.sgxsdk
    # ...

Install cachix:

nix-env -iA cachix -f https://cachix.org/api/v1/install

Add the initc3 cache:

cachix use initc3

Invoking nix-build to build your derivation should automatically pull the sgxsdk binary dependency from the cache.

A note about the Architectural Enclaves (ae.nix)

The Architectural Enclaves are enclaves that Intel provides, and are normally built from source and signed by Intel. Intel provides a toolchain to verify their reproducibility, but this toolchain is arguably cumbersome.

In an attempt to improve this existing toolchain, ae.nix is meant to be a stepping stone towards a different approach that could be used by both Intel and a verifier.

In this approach, both Intel and a verifier would simply run nix-build to build the enclaves, and sign them afterwards with their respective private keys. A verifier would then follow Verify Intel(R) Prebuilt AE Reproducibility to verify that the enclaves they've built match the ones provided by Intel.