The results delivered by the Sphinx project were overwhelmingly positive. The project achieved its primary objective of ensuring proper functionality and interoperability across various products from a wide range of manufacturers. One reason for this success was undoubtedly the use of international standards such as S/MIME (Secure Multipurpose Internet Mail Extension), PKCS (Public Key Cryptography Standard), X.509 (international standard for public key certificates) and MailTrusT.

Routine testing is essential in order to ensure the future interoperability of the products. This is because manufacturers may quite possibly differ in their interpretation of these international standards. Such testing is guaranteed by the Federal Office for Information Security (BSI). At regular intervals, the BSI conducts interoperability tests and publishes the results that it obtains.

It also proved possible to meet the prerequisites for the large-scale rollout of security systems based on Public Key Infrastructure (PKI). As a result of the Sphinx project results, the BSI set up and continues to operate a Policy Certificate Authority (PCA) for use by the public administration in Germany. Interested certificate authorities (CAs) can apply to have a CA certificate issued to them from this PCA.