Patent ID: 11876888
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. An encryption device comprising:
processing circuitry to:
acquire a plaintext M;
divide the acquired plaintext M, every b bits from a beginning, the b bits being a block size of an encryption function E of a block cipher, thereby generating b-bit values M1, . . . , Mm-1 and a value Mm having 1 or more bits to b or less bits;
assign a b-bit value H1 to a value M0, and for each integer i of i=1, . . . , m in an ascending order, to take a value Mi-1 as input to the encryption function E, thereby calculating a value S1(i), and to calculate a value Ci from the value S1(i) and a value Mi;
assign an r-bit value H2 to a value S2(0), and for each integer i of i=1, . . . , m in an ascending order, to calculate a value S2(i) from the calculated value S1(i) and from a value S2(i−1);
generate a ciphertext C from a value Ci for each integer i of i=1, . . . , m; and
generate a (b+r)-bit authenticator T by using a value S1(m) and a value S2(m).