Conex is a utility for verify and attest release integrity and authenticity of community repositories through the use of cryptographic signatures (RSA-PSS-SHA256). It is based on the update framework, especially on their CCS 2010 paper, and adapted to the requirements of the opam repository.

The developer sign their release checksums and build instructions. A quorum (with a configurable threshold) of repository maintainers signs the package name to developer key relation. These repository maintainers are enrolled by a quorum of offline root keys.

The TUF spec has a good overview of attacks and threat model, both of which are shared by conex.