Patent ID: 8345865

Claim:
A block cipher Academy, Research Institute and Agency (ARIA) substitution apparatus, the apparatus comprising: an Sbox operation unit for performing operations of substitution boxes S 1 , S 1 −1 , S 2 , and S 2 −1 , the Sbox operation unit comprising: a first inverse affine transformation unit coupled to receive an input value, the first inverse affine transformation unit configured to perform an inverse affine operation for obtaining an inverse substitution box S 1 −1 with respect to the input value; a second inverse affine transformation unit coupled to receive the input value, the second inverse affine transformation unit configured to perform an inverse affine operation for obtaining an inverse substitution box S 2 −1 with respect to the input value; a finite field inverse element operation unit configured to: compute an inverse element of GF(2 8 ) with respect to the input value in an S 1 operation mode or in an S 2 operation mode, compute an inverse element of GF(2 8 ) with respect to a value of a result value of the first inverse affine transformation unit in an S 1 −1 operation mode, and computing an inverse element of GF(2 8 ) with respect to the input value or a result value of the second inverse affine transformation unit in an S 2 −1 mode, a first affine transformation unit configured to perform an affine operation for obtaining a substitution box S 1 with respect to a result value of the finite field inverse element operation unit; a second affine transformation unit configured to perform an affine operation for obtaining a substitution box S 2 with respect to a result value of the finite field inverse element operation unit; a first multiplexer configured to determine an input of the finite field inverse element operation unit under control of the control unit; and a second multiplexer configured to select any one of the output value of the first affine transformation unit, the output value of the second affine transformation unit or the result value of the finite field inverse element operation unit as the result value of the Sbox operation unit under the control of the control unit; and a control unit coupled to the Sbox operation unit and configured to set an operation mode of the Sbox operation unit to one of the S 1 operation mode, the S 1 −1 operation mode, the S 2 operation mode, and the S 2 −1 operation mode.