30
KD6Putaran 7 = KE6-Putaran2 = 1000101010000010 KD1Putaran 8 = InverseKE1-Putaran2 = 0100000011001111
KD2Putaran 8 = MinusKE3-Putaran2 = 0110000101111000 KD3Putaran 8 = MinusKE2-Putaran2 = 1010110110110111
KD4Putaran 8 = InverseKE4-Putaran2 = 0100000111010110 KD5Putaran 8 = KE5-Putaran1 = 0100010001000101
KD6Putaran 8 = KE6-Putaran1 = 0100000100100000 KD1Putaran 9 = InverseKE1-Putaran1 = 0011001101110101
KD2Putaran 9 = MinusKE2-Putaran1 = 1010101110110001 KD3Putaran 9 = MinusKE3-Putaran1 = 1011101110111111
KD4Putaran 9 = InverseKE4-Putaran1 = 0111110001000101
3.1.2.2. Proses Enkripsi
Proses enkripsi dari metoda IDEA terdiri dari 8 iterasi putaran ditambah satu putaran transformasi output. Proses ini memiliki input data plaintext 64 bit yang identik
dengan 16 digit heksadesimal atau 8 karakter.
Proses enkripsi dari metoda IDEA dapat dilihat pada contoh berikut ini. Misalkan plaintext = ‘facebook’ dengan kunci yang dihasilkan di atas, maka proses
enkripsinya adalah sebagai berikut :
PROSES ENKRIPSI PUTARAN - 1
01 L1 = X1 K1 mod 216 + 1 = 0110011001100001 0011000100110000 mod 216 + 1 = 1010111110000101
02 L2 = X2 + K2 mod 216 = 0110001101100101 + 0011000000110001 mod 216 = 1001001110010110
03 L3 = X3 + K3 mod 216 = 0110001001101111 + 0011000100110000 mod 216 = 1001001110011111
04 L4 = X4 K4 mod 216 + 1 = 0110111101101011 0011000100110001 mod 216 + 1 = 1011100100010011
05 L5 = L1 XOR L3 = 1010111110000101 XOR 1001001110011111 = 0011110000011010
Universitas Sumatera Utara
31
06 L6 = L2 XOR L4 = 1001001110010110 XOR 1011100100010011 = 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 = 1010111110000101 XOR 1110101010001001 = 0100010100001100
12 L12 = L3 XOR L9 = 1001001110011111 XOR 1110101010001001 = 0111100100010110
13 L13 = L2 XOR L10 = 1001001110010110 XOR 0101100111110111 = 1100101001100001
14 L14 = L4 XOR L10 = 1011100100010011 XOR 0101100111110111 = 1110000011100100
Untuk putaran berikutnya : X1 = L11 = 0100010100001100
X2 = L12 = 0111100100010110 X3 = L13 = 1100101001100001
X4 = L14 = 1110000011100100 PUTARAN - 2
01 L1 = X1 K1 mod 216 + 1 = 0100010100001100 0011000100110001 mod 216 + 1 = 0111011000001000
02 L2 = X2 + K2 mod 216 = 0111100100010110 + 0011000000110000 mod 216 = 1010100101000110
03 L3 = X3 + K3 mod 216 = 1100101001100001 + 0110001001100010 mod 216 = 0010110011000011
04 L4 = X4 K4 mod 216 + 1 = 1110000011100100 0110000001100010 mod 216 + 1 = 0100001010011101
05 L5 = L1 XOR L3 = 0111011000001000 XOR 0010110011000011 = 0101101011001011
06 L6 = L2 XOR L4 = 1010100101000110 XOR 0100001010011101 = 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
Universitas Sumatera Utara
32
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 = 0111011000001000 XOR 0110001000000110 = 0001010000001110
12 L12 = L3 XOR L9 = 0010110011000011 XOR 0110001000000110 = 0100111011000101
13 L13 = L2 XOR L10 = 1010100101000110 XOR 1011011011011000 = 0001111110011110
14 L14 = L4 XOR L10 = 0100001010011101 XOR 1011011011011000 = 1111010001000101
Untuk putaran berikutnya : X1 = L11 = 0001010000001110
X2 = L12 = 0100111011000101 X3 = L13 = 0001111110011110
X4 = L14 = 1111010001000101 PUTARAN - 3
01 L1 = X1 K1 mod 216 + 1 = 0001010000001110 0110001001100010 mod 216 + 1 = 0000000110100111
02 L2 = X2 + K2 mod 216 = 0100111011000101 + 0110001001100000 mod 216 = 1011000100100101
03 L3 = X3 + K3 mod 216 = 0001111110011110 + 0110000001100010 mod 216 = 1000000000000000
04 L4 = X4 K4 mod 216 + 1 = 1111010001000101 0110000001100000 mod 216 + 1 = 0001110111101011
05 L5 = L1 XOR L3 = 0000000110100111 XOR 1000000000000000 = 1000000110100111
06 L6 = L2 XOR L4 = 1011000100100101 XOR 0001110111101011 = 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
11 L11 = L1 XOR L9 = 0000000110100111 XOR 0010011001011001 = 0010011111111110
Universitas Sumatera Utara
33
12 L12 = L3 XOR L9 = 1000000000000000 XOR 0010011001011001 = 1010011001011001
13 L13 = L2 XOR L10 = 1011000100100101 XOR 1110001010001111 = 0101001110101010
14 L14 = L4 XOR L10 = 0001110111101011 XOR 1110001010001111 = 1111111101100100
Untuk putaran berikutnya : X1 = L11 = 0010011111111110
X2 = L12 = 1010011001011001 X3 = L13 = 0101001110101010
X4 = L14 = 1111111101100100 PUTARAN - 4
01 L1 = X1 K1 mod 216 + 1 = 0010011111111110 1100000011000100 mod 216 + 1 = 0000000001011011
02 L2 = X2 + K2 mod 216 = 1010011001011001 + 1100010011000100 mod 216 = 0110101100011101
03 L3 = X3 + K3 mod 216 = 0101001110101010 + 1100000011000000 mod 216 = 0001010001101010
04 L4 = X4 K4 mod 216 + 1 = 1111111101100100 1100010011000000 mod 216 + 1 = 0101011010111001
05 L5 = L1 XOR L3 = 0000000001011011 XOR 0001010001101010 = 0001010000110001
06 L6 = L2 XOR L4 = 0110101100011101 XOR 0101011010111001 = 0011110110100100
07 L7 = L5 K5 mod 216 + 1 = 0001010000110001 1100000011000100 mod 216 + 1 = 0010011001010000
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 = 0000000001011011 XOR 0111101000101111 = 0111101001110100
12 L12 = L3 XOR L9 = 0001010001101010 XOR 0111101000101111 = 0110111001000101
13 L13 = L2 XOR L10 = 0110101100011101 XOR 1010000001111111 = 1100101101100010
14 L14 = L4 XOR L10 = 0101011010111001 XOR 1010000001111111 = 1111011011000110
Universitas Sumatera Utara
34
Untuk putaran berikutnya : X1 = L11 = 0111101001110100
X2 = L12 = 0110111001000101 X3 = L13 = 1100101101100010
X4 = L14 = 1111011011000110 PUTARAN - 5
01 L1 = X1 K1 mod 216 + 1 = 0111101001110100 1000100110000001 mod 216 + 1 = 1000011010101111
02 L2 = X2 + K2 mod 216 = 0110111001000101 + 1000100110001001 mod 216 = 1111011111001110
03 L3 = X3 + K3 mod 216 = 1100101101100010 + 1000100110000001 mod 216 = 0101010011100011
04 L4 = X4 K4 mod 216 + 1 = 1111011011000110 1000000110001001 mod 216 + 1 = 0101100100011001
05 L5 = L1 XOR L3 = 1000011010101111 XOR 0101010011100011 = 1101001001001100
06 L6 = L2 XOR L4 = 1111011111001110 XOR 0101100100011001 = 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 = 1000011010101111 XOR 1011100001011010 = 0011111011110101
12 L12 = L3 XOR L9 = 0101010011100011 XOR 1011100001011010 = 1110110010111001
13 L13 = L2 XOR L10 = 1111011111001110 XOR 1001001001000101 = 0110010110001011
14 L14 = L4 XOR L10 = 0101100100011001 XOR 1001001001000101 = 1100101101011100
Untuk putaran berikutnya : X1 = L11 = 0011111011110101
X2 = L12 = 1110110010111001 X3 = L13 = 0110010110001011
X4 = L14 = 1100101101011100 PUTARAN - 6
Universitas Sumatera Utara
35
01 L1 = X1 K1 mod 216 + 1 = 0011111011110101 1000000110001001 mod 216 + 1 = 0000011001000010
02 L2 = X2 + K2 mod 216 = 1110110010111001 + 1000100110001001 mod 216 = 0111011001000010
03 L3 = X3 + K3 mod 216 = 0110010110001011 + 0001001100010011 mod 216 = 0111100010011110
04 L4 = X4 K4 mod 216 + 1 = 1100101101011100 0000001100000011 mod 216 + 1 = 0111001110110000
05 L5 = L1 XOR L3 = 0000011001000010 XOR 0111100010011110 = 0111111011011100
06 L6 = L2 XOR L4 = 0111011001000010 XOR 0111001110110000 = 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 = 0000011001000010 XOR 1000011110001011 = 1000000111001001
12 L12 = L3 XOR L9 = 0111100010011110 XOR 1000011110001011 = 1111111100010101
13 L13 = L2 XOR L10 = 0111011001000010 XOR 0100111010110100 = 0011100011110110
14 L14 = L4 XOR L10 = 0111001110110000 XOR 0100111010110100 = 0011110100000100
Untuk putaran berikutnya : X1 = L11 = 1000000111001001
X2 = L12 = 1111111100010101 X3 = L13 = 0011100011110110
X4 = L14 = 0011110100000100 PUTARAN - 7
01 L1 = X1 K1 mod 216 + 1 = 1000000111001001 0001001100000011 mod 216 + 1 = 0110011010111000
02 L2 = X2 + K2 mod 216 = 1111111100010101 + 0001001100010011 mod 216 = 0001001000101000
03 L3 = X3 + K3 mod 216 = 0011100011110110 + 0001001100010011 mod 216 = 0100110000001001
Universitas Sumatera Utara
36
04 L4 = X4 K4 mod 216 + 1 = 0011110100000100 0000001100010011 mod 216 + 1 = 1001001010010001
05 L5 = L1 XOR L3 = 0110011010111000 XOR 0100110000001001 = 0010101010110001
06 L6 = L2 XOR L4 = 0001001000101000 XOR 1001001010010001 = 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 = 0110011010111000 XOR 1011011111101001 = 1101000101010001
12 L12 = L3 XOR L9 = 0100110000001001 XOR 1011011111101001 = 1111101111100000
13 L13 = L2 XOR L10 = 0001001000101000 XOR 0011001100101001 = 0010000100000001
14 L14 = L4 XOR L10 = 1001001010010001 XOR 0011001100101001 = 1010000110111000
Untuk putaran berikutnya : X1 = L11 = 1101000101010001
X2 = L12 = 1111101111100000 X3 = L13 = 0010000100000001
X4 = L14 = 1010000110111000 PUTARAN - 8
01 L1 = X1 K1 mod 216 + 1 = 1101000101010001 0010011000100110 mod 216 + 1 = 1111100011010110
02 L2 = X2 + K2 mod 216 = 1111101111100000 + 0000011000100110 mod 216 = 0000001000000110
03 L3 = X3 + K3 mod 216 = 0010000100000001 + 0010011000100110 mod 216 = 0100011100100111
04 L4 = X4 K4 mod 216 + 1 = 1010000110111000 0010011000000110 mod 216 + 1 = 0000001001001011
05 L5 = L1 XOR L3 = 1111100011010110 XOR 0100011100100111 = 1011111111110001
06 L6 = L2 XOR L4 = 0000001000000110 XOR 0000001001001011 = 0000000001001101
Universitas Sumatera Utara
37
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 = 1111100011010110 XOR 1101110011111010 = 0010010000101100
12 L12 = L3 XOR L9 = 0100011100100111 XOR 1101110011111010 = 1001101111011101
13 L13 = L2 XOR L10 = 0000001000000110 XOR 0000010000100110 = 0000011000100000
14 L14 = L4 XOR L10 = 0000001001001011 XOR 0000010000100110 = 0000011001101101
Untuk transformasi output : X1 = L11 = 0010010000101100
X2 = L13 = 0000011000100000 X3 = L12 = 1001101111011101
X4 = L14 = 0000011001101101 TRANSFORMASI OUTPUT
01 Y1 = X1 K1 mod 216 + 1 = 0010010000101100 0000110001001100 mod 216 + 1 = 1100101101010100
02 Y2 = X2 + K2 mod 216 = 0000011000100000 + 0100110000001100 mod 216 = 0101001000101100
03 Y3 = X3 + K3 mod 216 = 1001101111011101 + 0100110001001100 mod 216 = 1110100000101001
04 Y4 = X4 K4 mod 216 + 1 = 0000011001101101 0100110001001100 mod 216 + 1 = 0100001001110010
Hasil Enkripsi : Y1 = 1100101101010100 = ËT
Y2 = 0101001000101100 = R, Y3 = 1110100000101001 = è
Y4 = 0100001001110010 = Br Cipher text = ËTR,èBr
Universitas Sumatera Utara
38
3.1.2.3. Proses Dekripsi
