Provides system authentication. IPsec uses a message authentication code (MAC) function by calculating the Integrity Check Value (ICV) to provide data origin authentication. This means the receiving system knows what system sent the data. However, it does not mean that the actual user is authenticated, only the system that sent the information. If user authentication is required, credentials would need to be sent and verified, or a digital signature would need to be used. A symmetric key is not bound to an individual's identity as credentials and private keys are.