GSS-API provides three types of security services:
Authentication – The basic security offered by GSS-API is authentication. Authentication is the verification of an identity. If a user is authenticated, the system assumes that person is the one who is entitled to operate under that user name.
Integrity – Integrity is the verification of the data's validity. Even if data comes from a valid user, the data itself could have become corrupted or compromised. Integrity ensures that a message is complete as intended, with nothing added and nothing missing. GSS-API provides for data to be accompanied by a cryptographic tag, known as an Message Integrity Code (MIC). The MIC proves that the data that you receive is the same as the data that the sender transmitted.
Confidentiality – Confidentiality ensures that a third party who intercepted the message would have a difficult time reading the contents. Neither authentication nor integrity modify the data. If the data is somehow intercepted, others can read that data. GSS-API therefore allows data to be encrypted, provided that underlying mechanisms are available that support encryption. This encryption of data is known as confidentiality.