An encrypting apparatus includes a digest part using a SHA-2 algorithm of which a basic unit of operation is 32*Y (Y=1 or 2) bits. The digest part includes a shift register including a series of registers, and a predetermined number of adders performing an addition operation based on data stored in the shift register. The shift register includes a (32*Y)/X-bit register, where X=2 k (k is an integer such that 1≤k≤4 when Y=1 and 1≤k≤5 when Y=2). Each of the adders has a data width of (32*Y)/X bits and performs the addition operation in each cycle in which the data stored in the shift register is shifted between the registers with the data width of (32*Y)/X bits.