This part of ISO/IEC18033 specifies block ciphers. A block cipher maps blocks of n bits to blocks of n bits, under the control of a key of k bits. A total of eight different block ciphers are defined. They are categorized in Table1. Table1 Block ciphers specified Block length Algorithm name (see #) Key length 64bits TDEA (4.2) 128 or 192bits MISTY (4.3) 128bits CAST-128 (4.4) HIGHT (4.5) 128bits AES (5.2) 128, 192 or 256bits Camellia (5.3) SEED (5.4) 128bits SM4 (5.5) The algorithms specified in this part of ISO/IEC18033 have been assigned object identifiers in accordance with ISO/IEC9834. The list of assigned object identifiers is given in AnnexB. Any changes to the specification of the algorithms resulting in a change of functional behaviour will result in a change of the object identifier assigned to the algorithm.