Patent ID: 7471789

Claim:
An encryption circuit, comprising: a plurality of operation circuits which are connected; and a control circuit dividing data to plural parts for providing to each of said plurality of operation circuits and controlling said plurality of operation circuits to provide encryption or decryption control; wherein each of said plurality of operation circuits includes a first register holding corresponding part of data as operation data, an addition and subtraction circuit performing addition and subtraction with respect to the operation data held in said first register, a right-shift circuit performing right-shift with respect to an operation result by said addition and subtraction circuit, and a second register holding an operation result by said right-shift circuit, wherein said addition and subtraction circuit in a first operation circuit performs addition and subtraction using a carry-in signal supplied from a second operation circuit, and outputs a carry-out signal as said carry-in signal of a third operation circuit, wherein a right-shift circuit in said first operation circuit performs right-shift using a right shift-in signal supplied from said third operation circuit, and outputs a right shift-out signal as said right shift-in signal of said second operation circuit, and wherein said first operation circuit receives said carry-out signal from said second operation circuit before starting a calculation thereof, receives said shift-in signal from said third operation circuit during performing the calculation thereof, supplies said carry-out signal to said third operation circuit before starting the calculation of the third operation circuit, and supplies said shift-out signal to said second operation circuit during performing the calculation of the second operation circuit.