in-toto

In the realm of software supply chain security, one of the critical challenges is ensuring the integrity of a software product from its initiation to its end-user installation. in-toto addresses this challenge by providing a transparent and verifiable record of all steps performed in the software supply chain.

Technically, in-toto operates as an open metadata standard that can be integrated into a software's supply chain toolchain. It generates and tracks link metadata for each step in the supply chain, allowing users to verify if each step was intended and performed by the correct actor. This is achieved through the use of provenance agents, such as the in-toto Jenkins plugin, which track and sign metadata in a secure and distributed manner.

Operationally, in-toto requires careful consideration of its scope and limitations. For instance, it is designed to protect the integrity of artifact contents but not their metadata, which could potentially allow attackers to manipulate file permissions or other metadata. Supply chain owners are advised to use dedicated file container formats that include permissions as part of the file contents to mitigate this risk.

From a technical standpoint, in-toto supports multiple programming languages, including Python 3 and Go, with the Python reference implementation having reached v1.0 maturity. The framework has undergone a thorough security audit, which identified several issues that have been addressed through clarifications in the specification and usage documentation. Despite these adjustments, the core security properties of in-toto remain robust, ensuring that the software supply chain remains secure and transparent.