Patent ID: 6891951

Claim:
A method of generating key information, comprising the steps of: rearranging bits of a first bit sequence in a first matrix according to a predetermined arrangement rule, the first bit sequence representing information being a base of a key; forming blocks in the first matrix, wherein each of the blocks has bits, the number of which is smaller than the number of bits composing the first matrix; executing logical operation among bits in each of the blocks and generating a bit being a result of the logical operation; combining the logical-operation-result bits into a second bit sequence, wherein the number of bits composing the second bit sequence is smaller than the number of bits composing the first bit sequence; and accessing a second matrix composed of predetermined third bit sequences and reading out one from among the third bit sequences in response to the second bit sequence, and outputting the read-out third bit sequence as information representative of the key, wherein the number of bits composing each of the third bit sequences is smaller than the number of bits composing the second bit sequence.