Patent ID: 7305085

Claim:
An apparatus for encrypting block data of a first bit length comprsing: encrypting sections connected in series, each of the encrypting sections comprising, first units each configured to randomize first subblock data of a second bit length which are obtained by dividing the block data of the first bit length, and a second unit configured to receive plural items of the randomized first subblock data output from the first units, the received plural items of the randomized first subblock data being of the first bit length, to diffuse the received plural items of the randomized first subblock data of the first bit length and to supply a result of diffusion to first units in a succeeding encrypting section, and wherein each of the first units comprises first subunits each configured to randomize second subblock data of a third bit length which are obtained by dividing the first subblock data of the second bit length, a second subunit configured to receive plural items of the randomized second subblock data output from the first subunits, the received plural items of the randomized second subblock data being of the second bit length and to diffuse the received plural items of the randomized second subblock data of the second bit length, and third subunits configured to receive the diffused second subblock data of the second bit length which is output from the second subunit and each configured to randomize the second subblock data of the third bit length, and wherein any one of the first subunits is connected to any one of the first subunits in the succeeding encrypting section via at least two paths.