The Notary Project is a set of specifications and tools intended to provide a cross-industry standard for securing software supply chains by using authentic container images and other OCI artifacts. An external actor with control of a compromised container registry can provide outdated versions of OCI artifacts, such as Images. This could lead artifact consumers with relaxed trust policies (such as `permissive` instead of `strict`) to potentially use artifacts with signatures that are no longer valid, making them susceptible to any exploits those artifacts may contain. In Notary Project, an artifact publisher can control the validity period of artifact by specifying signature expiry during the signing process. Using shorter signature validity periods along with processes to periodically re