ISO/IEC 19772:2009 specifies six methods for authenticated encryption, i.e. defined ways of processing a data string with the following security objectives: data confidentiality, i.e. protection against unauthorized disclosure of data; data integrity, i.e. protection that enables the recipient of data to verify that it has not been modified; data origin authentication, i.e. protection that enables the recipient of data to verify the identity of the data originator. All six methods specified in ISO/IEC 19772:2009 require the originator and the recipient of the protected data to share a secret key.