The Industrial SignatureInteroperability Specifications (ISIS) define the message and file formats for services according to the Signature Act (SigG). The file formats of ISIS include the formats for digital certificates, time stamps and directory services
. The ISIS specifications were defined by the Federal Office for Information Security (BSI) in cooperation with the Trust Center for Digital Signatures (AGTC) working group. They are intended to support medium-sized companies in implementing an information security management system (ISMS) in accordance with ISO 27001. To facilitate this approach, ISIS12 documents an approach consisting of twelve iterative steps, including the creation of guidelines, employee buy-in, the establishment of a security team, the documentation of measures, and many others.