Codechain — code trust through hash chains

In code we trust: Secure multiparty code reviews with signatures and hash chains.

The most common signing mechanism for open-source software is using GPG signatures. For example, GPG is used to sign Git commits and Debian packages. There is no built-in mechanism for key rotation and key compromise. And if forced to, a single developer can subvert all machines which trust the corresponding GPG key.

That's where the Codechain tool comes in. It establishes code trust via multi-party reviews recorded in unmodifiable hash chains.

Codechain allows to only publish code that has been reviewed by a preconfigured set of reviewers. The signing keys can be rotated and the reviewer set flexibly changed.

Every published code state is uniquely identified by a deterministic source tree hash stored in the hash chain, signed by a single responsible developer.

Codechain uses files to store the hash chain, not a distributed "blockchain".

Installation

Bootstrapping

To install a trusted Codechain version that can be updated in a trusted way you have to boostrap it.

Developer version

To install the latest developer version (not recommended):

go get -u -v github.com/frankbraun/codechain/...

(How to install Go. Add $GOPATH/bin to your $PATH.)

Config directories

codechain uses the following config directories:

• POSIX (Linux/BSD): ~/.config/codechain
• Mac OS: $HOME/Library/Application Support/Codechain
• Windows: %LOCALAPPDATA%\Codechain
• Plan 9: $home/Codechain

secpkg and ssotpub use accordingly named directories.

Features

• Minimal code base, Go only, cross-platform.
• Single source of truth (SSOT) with DNS

Codechain depends on the git binary (for git diff), but that's optional.

Out of scope

• Source code management. Git and other VCS systems are good for that, Codechain can be used alongside them and solves a different problem.
• Code distribution (minimal support is provided via codechain createdist and codechain apply -f).
• Reproducible builds.

Documentation

• Walkthrough
• Presentation about Codechain
• Directory tree hashes and lists
• Hash chain file format
• Patchfile format
• SSOT with DNS TXT records
• Secure packages (.secpkg files)

Acknowledgments

Codechain has been heavily influenced by discussions with Jonathan Logan of Cryptohippie, Inc. Many thanks to Michael Parenti for the logo.