This International Standard establishes five modes of operation for applications of an n-bit block cipher (e.g. protection of data transmission, data storage). The defined modes only provide protection of data confidentiality. Protection of data integrity and requirements for padding the data are not within the scope of this International Standard. Also most modes do not protect the confidentiality of message length information. This International Standard specifies the modes of operation and gives recommendations for choosing values of parameters (as appropriate). The modes of operation specified in this International Standard have been assigned object identifiers in accordance with ISO/IEC 9834. The list of assigned object identifiers is given in Annex A. In applications in which object identifiers are used, the object identifiers specified in Annex A are to be used in preference to any other object identifiers that may exist for the mode concerned. NOTE – Annex B (informative) contains comments on the properties of each mode. Block ciphers are specified in ISO/IEC 18033-3.