Malware Resistance
The English user guide is currently in beta preview. Most of the documents have been automatically translated from the Japanese version. Should you find any inaccuracies, please reach out to Flatt Security.
Takumi Images has structural resistance against supply-chain attacks that target software updates. This is not only a matter of detecting and blocking attacks; the build structure itself reduces the places where compromise can enter.
Hermetic builds and complete source visibility
Takumi Images uses hermetic builds. Nix builds each derivation in a sandbox and blocks access to inputs that were not declared, including the network and undeclared files. External source retrieval is limited to fixed-output derivations (FODs), where the content hash is pinned in advance.
Because of this property, Takumi Images can mechanically enumerate the upstream URL, revision, and hash of every source that enters an image, including sources for the build tools. If the inspection target cannot be enumerated, the scope of diff inspection cannot be defined. This completeness is the premise for the source review described below. See Deriving Nix Build Inputs for details.
Upstream source diff inspection
Takumi Images inspects the full upstream source diff included in each build.
For every enumerated source, Takumi Images retrieves the diff from the previous build to the current build and analyzes it for signs of malicious changes. Before publication, a separate check also looks for known package malware. See Upstream Malware Detection for details.
Detection limits
This inspection is not perfect. Judging whether a change is malicious can miss cases in principle. Passing inspection does not prove that a diff is non-malicious; it only means the current inspection found no sign of malicious behavior.