The BSI's Cloud Computing Compliance Criteria Catalogue, a German standard for assessing the security of cloud service providers.
C5 (Cloud Computing Compliance Criteria Catalogue) is a catalogue published by the BSI that defines a baseline of security requirements for cloud providers. Providers demonstrate compliance through an audit performed under recognized attestation standards.
It has become a common reference for cloud security in Germany, particularly where public sector and regulated customers need assurance about a provider's controls.