Proses Dekripsi Pembahasan Proses IDEA

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3.1.2.3. Proses Dekripsi

Proses dekripsi merupakan kebalikan dari proses enkripsi. Proses dekripsi menggunakan algoritma yang sama dengan proses enkripsi. Sebagai contoh, misalkan ingin didekripsikan kembali hasil enkripsi yang telah didapatkan di atas, maka proses dekripsinya adalah sebagai berikut : PROSES DEKRIPSI PUTARAN - 1 01 L1 = X1 K1 mod 216 + 1 = 1100101101010100 0010001000010011 mod 216 + 1 = 0010010000101100 02 L2 = X2 + K2 mod 216 = 0101001000101100 + 1011001111110100 mod 216 = 0000011000100000 03 L3 = X3 + K3 mod 216 = 1110100000101001 + 1011001110110100 mod 216 = 1001101111011101 04 L4 = X4 K4 mod 216 + 1 = 0100001001110010 0111011110010011 mod 216 + 1 = 0000011001101101 05 L5 = L1 XOR L3 = 0010010000101100 XOR 1001101111011101 = 1011111111110001 06 L6 = L2 XOR L4 = 0000011000100000 XOR 0000011001101101 = 0000000001001101 07 L7 = L5 K5 mod 216 + 1 = 1011111111110001 0010011000100110 mod 216 + 1 = 0010011100101100 08 L8 = L6 + L7 mod 216 = 0000000001001101 + 0010011100101100 mod 216 = 0010011101111001 09 L9 = L8 K6 mod 216 + 1 = 0010011101111001 0010011000000110 mod 216 + 1 = 1101110011111010 10 L10 = L7 + L9 mod 216 = 0010011100101100 + 1101110011111010 mod 216 = 0000010000100110 11 L11 = L1 XOR L9 = 0010010000101100 XOR 1101110011111010 = 1111100011010110 12 L12 = L3 XOR L9 = 1001101111011101 XOR 1101110011111010 = 0100011100100111 13 L13 = L2 XOR L10 = 0000011000100000 XOR 0000010000100110 = 0000001000000110 14 L14 = L4 XOR L10 = 0000011001101101 XOR 0000010000100110 = 0000001001001011 Untuk putaran berikutnya : X1 = L11 = 1111100011010110 X2 = L12 = 0100011100100111 Universitas Sumatera Utara 39 X3 = L13 = 0000001000000110 X4 = L14 = 0000001001001011 PUTARAN - 2 01 L1 = X1 K1 mod 216 + 1 = 1111100011010110 1110111100100110 mod 216 + 1 = 1101000101010001 02 L2 = X2 + K2 mod 216 = 0100011100100111 + 1101100111011010 mod 216 = 0010000100000001 03 L3 = X3 + K3 mod 216 = 0000001000000110 + 1111100111011010 mod 216 = 1111101111100000 04 L4 = X4 K4 mod 216 + 1 = 0000001001001011 0101011110000000 mod 216 + 1 = 1010000110111000 05 L5 = L1 XOR L3 = 1101000101010001 XOR 1111101111100000 = 0010101010110001 06 L6 = L2 XOR L4 = 0010000100000001 XOR 1010000110111000 = 1000000010111001 07 L7 = L5 K5 mod 216 + 1 = 0010101010110001 0000011000100110 mod 216 + 1 = 0111101101000000 08 L8 = L6 + L7 mod 216 = 1000000010111001 + 0111101101000000 mod 216 = 1111101111111001 09 L9 = L8 K6 mod 216 + 1 = 1111101111111001 0000011000000110 mod 216 + 1 = 1011011111101001 10 L10 = L7 + L9 mod 216 = 0111101101000000 + 1011011111101001 mod 216 = 0011001100101001 11 L11 = L1 XOR L9 = 1101000101010001 XOR 1011011111101001 = 0110011010111000 12 L12 = L3 XOR L9 = 1111101111100000 XOR 1011011111101001 = 0100110000001001 13 L13 = L2 XOR L10 = 0010000100000001 XOR 0011001100101001 = 0001001000101000 14 L14 = L4 XOR L10 = 1010000110111000 XOR 0011001100101001 = 1001001010010001 Untuk putaran berikutnya : X1 = L11 = 0110011010111000 X2 = L12 = 0100110000001001 X3 = L13 = 0001001000101000 X4 = L14 = 1001001010010001 PUTARAN - 3 01 L1 = X1 K1 mod 216 + 1 = 0110011010111000 1010111100000000 mod 216 + 1 = 1000000111001001 Universitas Sumatera Utara 40 02 L2 = X2 + K2 mod 216 = 0100110000001001 + 1110110011101101 mod 216 = 0011100011110110 03 L3 = X3 + K3 mod 216 = 0001001000101000 + 1110110011101101 mod 216 = 1111111100010101 04 L4 = X4 K4 mod 216 + 1 = 1001001010010001 1000100001001100 mod 216 + 1 = 0011110100000100 05 L5 = L1 XOR L3 = 1000000111001001 XOR 1111111100010101 = 0111111011011100 06 L6 = L2 XOR L4 = 0011100011110110 XOR 0011110100000100 = 0000010111110010 07 L7 = L5 K5 mod 216 + 1 = 0111111011011100 0001001100000011 mod 216 + 1 = 1100011100101001 08 L8 = L6 + L7 mod 216 = 0000010111110010 + 1100011100101001 mod 216 = 1100110100011011 09 L9 = L8 K6 mod 216 + 1 = 1100110100011011 0000001100010011 mod 216 + 1 = 1000011110001011 10 L10 = L7 + L9 mod 216 = 1100011100101001 + 1000011110001011 mod 216 = 0100111010110100 11 L11 = L1 XOR L9 = 1000000111001001 XOR 1000011110001011 = 0000011001000010 12 L12 = L3 XOR L9 = 1111111100010101 XOR 1000011110001011 = 0111100010011110 13 L13 = L2 XOR L10 = 0011100011110110 XOR 0100111010110100 = 0111011001000010 14 L14 = L4 XOR L10 = 0011110100000100 XOR 0100111010110100 = 0111001110110000 Untuk putaran berikutnya : X1 = L11 = 0000011001000010 X2 = L12 = 0111100010011110 X3 = L13 = 0111011001000010 X4 = L14 = 0111001110110000 PUTARAN - 4 01 L1 = X1 K1 mod 216 + 1 = 0000011001000010 0111100111111000 mod 216 + 1 = 0011111011110101 02 L2 = X2 + K2 mod 216 = 0111100010011110 + 1110110011101101 mod 216 = 0110010110001011 03 L3 = X3 + K3 mod 216 = 0111011001000010 + 0111011001110111 mod 216 = 1110110010111001 04 L4 = X4 K4 mod 216 + 1 = 0111001110110000 0111111111010110 mod 216 + 1 = 1100101101011100 Universitas Sumatera Utara 41 05 L5 = L1 XOR L3 = 0011111011110101 XOR 1110110010111001 = 1101001001001100 06 L6 = L2 XOR L4 = 0110010110001011 XOR 1100101101011100 = 1010111011010111 07 L7 = L5 K5 mod 216 + 1 = 1101001001001100 1000000110000001 mod 216 + 1 = 1101100111101011 08 L8 = L6 + L7 mod 216 = 1010111011010111 + 1101100111101011 mod 216 = 1000100011000010 09 L9 = L8 K6 mod 216 + 1 = 1000100011000010 1000100110001001 mod 216 + 1 = 1011100001011010 10 L10 = L7 + L9 mod 216 = 1101100111101011 + 1011100001011010 mod 216 = 1001001001000101 11 L11 = L1 XOR L9 = 0011111011110101 XOR 1011100001011010 = 1000011010101111 12 L12 = L3 XOR L9 = 1110110010111001 XOR 1011100001011010 = 0101010011100011 13 L13 = L2 XOR L10 = 0110010110001011 XOR 1001001001000101 = 1111011111001110 14 L14 = L4 XOR L10 = 1100101101011100 XOR 1001001001000101 = 0101100100011001 Untuk putaran berikutnya : X1 = L11 = 1000011010101111 X2 = L12 = 0101010011100011 X3 = L13 = 1111011111001110 X4 = L14 = 0101100100011001 PUTARAN - 5 01 L1 = X1 K1 mod 216 + 1 = 1000011010101111 1001011100111100 mod 216 + 1 = 0111101001110100 02 L2 = X2 + K2 mod 216 = 0101010011100011 + 0111011001111111 mod 216 = 1100101101100010 03 L3 = X3 + K3 mod 216 = 1111011111001110 + 0111011001110111 mod 216 = 0110111001000101 04 L4 = X4 K4 mod 216 + 1 = 0101100100011001 0111100111111000 mod 216 + 1 = 1111011011000110 05 L5 = L1 XOR L3 = 0111101001110100 XOR 0110111001000101 = 0001010000110001 06 L6 = L2 XOR L4 = 1100101101100010 XOR 1111011011000110 = 0011110110100100 07 L7 = L5 K5 mod 216 + 1 = 0001010000110001 1100000011000100 mod 216 + 1 = 0010011001010000 Universitas Sumatera Utara 42 08 L8 = L6 + L7 mod 216 = 0011110110100100 + 0010011001010000 mod 216 = 0110001111110100 09 L9 = L8 K6 mod 216 + 1 = 0110001111110100 1100010011000000 mod 216 + 1 = 0111101000101111 10 L10 = L7 + L9 mod 216 = 0010011001010000 + 0111101000101111 mod 216 = 1010000001111111 11 L11 = L1 XOR L9 = 0111101001110100 XOR 0111101000101111 = 0000000001011011 12 L12 = L3 XOR L9 = 0110111001000101 XOR 0111101000101111 = 0001010001101010 13 L13 = L2 XOR L10 = 1100101101100010 XOR 1010000001111111 = 0110101100011101 14 L14 = L4 XOR L10 = 1111011011000110 XOR 1010000001111111 = 0101011010111001 Untuk putaran berikutnya : X1 = L11 = 0000000001011011 X2 = L12 = 0001010001101010 X3 = L13 = 0110101100011101 X4 = L14 = 0101011010111001 PUTARAN - 6 01 L1 = X1 K1 mod 216 + 1 = 0000000001011011 0001011011110010 mod 216 + 1 = 0010011111111110 02 L2 = X2 + K2 mod 216 = 0001010001101010 + 0011111101000000 mod 216 = 0101001110101010 03 L3 = X3 + K3 mod 216 = 0110101100011101 + 0011101100111100 mod 216 = 1010011001011001 04 L4 = X4 K4 mod 216 + 1 = 0101011010111001 1101001000100010 mod 216 + 1 = 1111111101100100 05 L5 = L1 XOR L3 = 0010011111111110 XOR 1010011001011001 = 1000000110100111 06 L6 = L2 XOR L4 = 0101001110101010 XOR 1111111101100100 = 1010110011001110 07 L7 = L5 K5 mod 216 + 1 = 1000000110100111 1100010011000100 mod 216 + 1 = 1011110000110110 08 L8 = L6 + L7 mod 216 = 1010110011001110 + 1011110000110110 mod 216 = 0110100100000100 09 L9 = L8 K6 mod 216 + 1 = 0110100100000100 1100010011000100 mod 216 + 1 = 0010011001011001 10 L10 = L7 + L9 mod 216 = 1011110000110110 + 0010011001011001 mod 216 = 1110001010001111 Universitas Sumatera Utara 43 11 L11 = L1 XOR L9 = 0010011111111110 XOR 0010011001011001 = 0000000110100111 12 L12 = L3 XOR L9 = 1010011001011001 XOR 0010011001011001 = 1000000000000000 13 L13 = L2 XOR L10 = 0101001110101010 XOR 1110001010001111 = 1011000100100101 14 L14 = L4 XOR L10 = 1111111101100100 XOR 1110001010001111 = 0001110111101011 Untuk putaran berikutnya : X1 = L11 = 0000000110100111 X2 = L12 = 1000000000000000 X3 = L13 = 1011000100100101 X4 = L14 = 0001110111101011 PUTARAN - 7 01 L1 = X1 K1 mod 216 + 1 = 0000000110100111 1010010111100000 mod 216 + 1 = 0001010000001110 02 L2 = X2 + K2 mod 216 = 1000000000000000 + 1001111110011110 mod 216 = 0001111110011110 03 L3 = X3 + K3 mod 216 = 1011000100100101 + 1001110110100000 mod 216 = 0100111011000101 04 L4 = X4 K4 mod 216 + 1 = 0001110111101011 0101001111111111 mod 216 + 1 = 1111010001000101 05 L5 = L1 XOR L3 = 0001010000001110 XOR 0100111011000101 = 0101101011001011 06 L6 = L2 XOR L4 = 0001111110011110 XOR 1111010001000101 = 1110101111011011 07 L7 = L5 K5 mod 216 + 1 = 0101101011001011 0110001001100010 mod 216 + 1 = 0101010011010010 08 L8 = L6 + L7 mod 216 = 1110101111011011 + 0101010011010010 mod 216 = 0100000010101101 09 L9 = L8 K6 mod 216 + 1 = 0100000010101101 0110001001100000 mod 216 + 1 = 0110001000000110 10 L10 = L7 + L9 mod 216 = 0101010011010010 + 0110001000000110 mod 216 = 1011011011011000 11 L11 = L1 XOR L9 = 0001010000001110 XOR 0110001000000110 = 0111011000001000 12 L12 = L3 XOR L9 = 0100111011000101 XOR 0110001000000110 = 0010110011000011 13 L13 = L2 XOR L10 = 0001111110011110 XOR 1011011011011000 = 1010100101000110 Universitas Sumatera Utara 44 14 L14 = L4 XOR L10 = 1111010001000101 XOR 1011011011011000 = 0100001010011101 Untuk putaran berikutnya : X1 = L11 = 0111011000001000 X2 = L12 = 0010110011000011 X3 = L13 = 1010100101000110 X4 = L14 = 0100001010011101 PUTARAN - 8 01 L1 = X1 K1 mod 216 + 1 = 0111011000001000 0100101110111111 mod 216 + 1 = 0100010100001100 02 L2 = X2 + K2 mod 216 = 0010110011000011 + 1001110110011110 mod 216 = 1100101001100001 03 L3 = X3 + K3 mod 216 = 1010100101000110 + 1100111111010000 mod 216 = 0111100100010110 04 L4 = X4 K4 mod 216 + 1 = 0100001010011101 0010110111100100 mod 216 + 1 = 1110000011100100 05 L5 = L1 XOR L3 = 0100010100001100 XOR 0111100100010110 = 0011110000011010 06 L6 = L2 XOR L4 = 1100101001100001 XOR 1110000011100100 = 0010101010000101 07 L7 = L5 K5 mod 216 + 1 = 0011110000011010 0011000100110001 mod 216 + 1 = 0110111101101110 08 L8 = L6 + L7 mod 216 = 0010101010000101 + 0110111101101110 mod 216 = 1001100111110011 09 L9 = L8 K6 mod 216 + 1 = 1001100111110011 0011000000110001 mod 216 + 1 = 1110101010001001 10 L10 = L7 + L9 mod 216 = 0110111101101110 + 1110101010001001 mod 216 = 0101100111110111 11 L11 = L1 XOR L9 = 0100010100001100 XOR 1110101010001001 = 1010111110000101 12 L12 = L3 XOR L9 = 0111100100010110 XOR 1110101010001001 = 1001001110011111 13 L13 = L2 XOR L10 = 1100101001100001 XOR 0101100111110111 = 1001001110010110 14 L14 = L4 XOR L10 = 1110000011100100 XOR 0101100111110111 = 1011100100010011 Untuk transformasi output : X1 = L11 = 1010111110000101 X2 = L13 = 1001001110010110 X3 = L12 = 1001001110011111 X4 = L14 = 1011100100010011 Universitas Sumatera Utara 45 TRANSFORMASI OUTPUT 01 Y1 = X1 K1 mod 216 + 1 = 1010111110000101 0100100010000101 mod 216 + 1 = 0110011001100001 02 Y2 = X2 + K2 mod 216 = 1001001110010110 + 1100111111001111 mod 216 = 0110001101100101 03 Y3 = X3 + K3 mod 216 = 1001001110011111 + 1100111011010000 mod 216 = 0110001001101111 04 Y4 = X4 K4 mod 216 + 1 = 1011100100010011 0100101110111111 mod 216 + 1 = 0110111101101011 Hasil Dekripsi : Y1 = 0110011001100001 = fa Y2 = 0110001101100101 = ce Y3 = 0110001001101111 = bo Y4 = 0110111101101011 = ok Plain text = facebook

3.2. Perancangan