The algorithms contained in ISO 20215:2015 are recommended for use on space missions with a requirement for information (e.g., data, voice, and video) confidentiality, authentication, or authenticated confidentiality. The algorithms may be employed on any or all mission communications links such as the forward space link (e.g., telecommand), the return space link (e.g., telemetry, science data), as well as across the ground data network. They could as well be used to ensure confidentiality and authenticity of stored data.
A symmetric algorithm assumes that all communicating entities possess a shared secret (i.e., a ?key') which enables them to encrypt, decrypt, and authenticate information shared among them. The manner in which the shared secret is distributed and managed (key management) is not within the scope of this document. Further information on key management can be found in Space Missions Key Management Concept (reference [B22]).