Artifacts verification

Overview

Artifacts verification is a general description to describe the security steps realized by the package manager.

3 verifications are implemented in Mamba, on:

  • repositories packages index (experimental)

  • packages tarballs, fetched from package repo

  • packages files, expanded from tarballs

Repodata

The verification of repodata files is under active development based on The Update Framework specification.

The goal is to ensure that a package tarball metadata are correct (including size and checksums).

It relies on multiple (asymmetric) cryptographic keys to:

  • define one or multiple trusted public keys for a given package (also called target in that context)

  • add to the repodata files one or more (public key, signature) pair for each package tarball metadata

Further documentation will come soon.

Package tarball

Assuming a valid repodata (see the previous repodata verification), package tarball metadata are used to check if a tarball is valid or not after fetching it from a repository.

Package files

All the package files are listed in a paths.json file index extracted from the package tarball with files themselves.

This index also contains metadata such as the size and checksum (SHA-256) of each file of the package.

When a package has already been extracted during a previous operation, it can be directly re-used. The files sizes are nevertheless verified to be sure that they match package definition. It prevents from alteration of its content (manual editing of a file, etc.).

SHA-256 checksum verification can be additionally performed using extra safety checks configuration.

By default, Mamba will only emit a warning if one of those 2 checks (file size and checksum) are failing. You can also configure a different policy:

  • ignore

  • warn

  • throw

Note

After fetching a package tarball from a repo, its size and checksums are already verified (see the previous package tarball verification). There is no need to perform additional checks on each file.