Patent ID: 7212633

Claim:
An expansion key generating device operable to receive encryption key data as an input and operable to output a plurality of expansion key data comprising: a data dividing unit operable to receive the encryption key data, operable to divide the encryption key data into a plurality of part key data, and operable to output the plurality of part key data; and a plurality of key conversion units connected in series, each operable to receive the plurality of part key data as an input, and operable to output the expansion key data, wherein each of the plurality of key conversion units includes: an output calculation unit operable to receive as a plurality of input data, either the plurality of part key data or a plurality of output data from a preceding key conversion unit as a plurality of input data; execute a fixed conversion process for each of the plurality of input data such that each bit value of each of the plurality of input data does not interfere with each other, wherein said output calculation unit is operable to execute a rotation shift operation to at least one of the plurality of input data, where the bits of at least one of the plurality of input data are shifted according to a specific number; and subsequently output a plurality of output data to a subsequent key conversion unit; and an expansion key calculation unit operable to receive and combine the plurality of input data, and operable to generate and output the expansion key data.