Sylabs Singularity 3.0 through 3.5 lacks support for an Integrity Check. Singularity's sign and verify commands do not sign metadata found in the global header or data object descriptors of a SIF file.
https://github.com/hpcng/singularity/security/advisories/GHSA-m7j2-9565-4h9v
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00053.html
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00059.html
http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00046.html