VIGENEREE CIPHER
- Untuk melakukan enkripsi dan dekripsi menggunakan Vigenere Cipher, diperlukan bujursangkar Vigenere yang akan digunakan sebagai landasan untuk mengubah plaintext menjadi ciphertext berdasarkan kunci yang digunakan dan sebaliknya. Berikut ini adalah model potongan bujursangkar Vigenere dengan deret horizontal huruf paling atas(kapital-tebal) melambangkan plaintext dan deret vertikal huruf paling kiri (non kapital-tebal) melambangkan kunci:
Selain itu Enkripsi VIGENEREE dapat juga dilakukan dengan perhitungan menggunakan suatu fungsi. Maka secara umum, fungsi enkripsinya dapat ditulis sebagai:
c(H) = (uH + uK – 1) mod 26 = uC
Keterangan :
H = huruf plaintext
uH = urutan huruf plaintext pada alphabet
uK = urutan huruf kunci pada alphabet
uC = urutan huruf ciphertext pada alphabet
Contoh:
Plaintext:
PLAYFAIR CIPHER TERMASUK KE DALAM POLYGRAM CIPHER YANG MELAKUKAN SUBSTITUSI SECARA BIGRAM
Kunci: VIGENERE
Enkripsi dengan tabel (Bisa langsung ditemukan hasil enkripsinya):
P L A Y F A I R C I P H E R T E R M A S U K K E D A L A M P O L Y G R A V I G E N E R E V I G E N E R E V I G E N E R E V I G E N E R E V I G E K T G C S E Z V X Q V L R V K I M U G W H O B I Y I R E Z T F P T O X E
M C I P H E R Y A N G M E L A K U K A N S U B S T I T U S I S E C A R A N E R E V I G E N E R E V I G E N E R E V I G E N E R E V I G E N E R E
Z G Z T C M X C N R X Q Z T G O H O R R N C H WG M K Y N Q Y I P E I E
B I G R A M
V I G E N E
W Q M V N Q
Jika dengan menggunakan perhitungan fungsi, maka:
P + V = (16+22-1) mod 26 = 11 ==> K
L + I = (12+9-1) mod 26 = 20 ==> T
A + G = (1+7-1) mod 26 = 7 ==> G
Y + E = (25+5-1) mod 26 = 3 ==> C
F + N = (6+14-1) mod 26 = 19 ==> S
A + E = (1+5-1) mod 26 = 5 ==> E
I + R = (9+18-1) mod 26 = 26 ==> Z
R + E = (18+5-1) mod 26 = 22 ==> V
C + V = (3+22-1) mod 26 = 24 ==> X
I +I = (9+9-1) mod 26 = 17 ==> Q
P + G = (16+7-1) mod 26 = 22 ==> V
H + E = (8+5-1) mod 26 = 12 ==> L
E + N = (5+14-1) mod 26 = 18 ==> R
R + E= (18+5-1) mod 26 = 22 ==> V
T + R = (20+18-1) mod 26 = 11 ==> K
E + E = (5+5-1) mod 26 = 9 ==> I
R + V = (18+22-1) mod 26 = 13 ==> M
M + I = (13+9-1) mod 26 = 21 ==> U
A + G = (2+7-1) mod 26 = 7 ==> G
S + E = (19+5-1) mod 26 = 23 ==> W
U + N = (21+14-1) mod 26 = 8 ==> H
K + E = (11+5-1) mod 26 = 15 ==> O
K + R = (11+18-1) mod 26 = 2 ==> B
E + E = (5+5-1) mod 26 = 9 ==> I
D + V = (4+22-1) mod 26 = 25 ==> Y
A + I = (1+9-1) mod 26 = 9 ==> I
L + G = (12+7-1) mod 26 = 18 ==> R
A + E = (1+5-1) mod 26 = 5 ==> E
M + N = (13+14-1) mod 26 = 0 ==> Z
P + E = (16+5-1) mod 26 = 20 ==> T
O + R = (15+18-1) mod 26 = 6 ==> F
L + E = (12+5-1) mod 26 = 16 ==> P
Y + V = (25+22-1) mod 26 = 20 ==> T
G + I = (7+9-1) mod 26 = 15 ==> O
R + G = (18+7-1) mod 26 = 24 ==> X
A + E = (1+5-1) mod 26 = 5 ==> E
M + N = (13+14-1) mod 26 = 0 ==> Z
C + E = (3+5-1) mod 26 = 7 ==> G
I + R = (9+18-1) mod 26 = 0 ==> Z
P + E = (16+5-1) mod 26 = 20 ==> T
H + V = (8+22-1) mod 26 = 3 ==> C
E + I = (5+9-1) mod 26 = 13 ==> M
R + G = (18+7-1) mod 26 = 24 ==> X
Y + E = (25+5-1) mod 26 = 3 ==> C
A + N = (1+14-1) mod 26 = 14 ==> N
N + E = (14+5-1) mod 26 = 18 ==> R
G + R = (7+18-1) mod 26 = 24 ==> X
M + E = (13+5-1) mod 26 = 17 ==> Q
E + V = (5+22-1) mod 26 = 0 ==> Z
L + I = (12+9-1) mod 26 = 20 ==> T
A + G = (1+7-1) mod 26 = 7 ==> G
K + E = (11+5-1) mod 26 = 15 ==> O
U + N = (21+14-1) mod 26 = 8 ==> H
K + E = (11+5-1) mod 26 = 15 ==> O
A + R = (1+18-1) mod 26 = 18 ==> R
N + E = (14 +5-1)mod 26 = 18 ==> R
S + V = (19+22-1) mod 26 = 14 ==> N
U + I = (21+9-1) mod 26 = 3 ==> C
B + G = (2+7-1) mod 26 = 8 ==> H
S + E = (19+5-1) mod 26 = 23 ==> W
T + N = (20+14-1) mod 26 = 7 ==> G
I + E = (9+5-1) mod 26 = 13 ==> M
T + R = (20+18-1) mod 26 = 11 ==> K
U + E = (21+5-1) mod 26 = 25 ==> Y
S + V = (19+22-1) mod 26 = 14 ==> N
I + I = (9+9-1) mod 26 = 17 ==> Q
S + G = (19+7-1) mod 26 = 25 ==> Y
E + E = (5+5-1) mod 26 = 9 ==> I
C + N = (3+14-1) mod 26 = 16 ==> P
A + E = (1+5-1) mod 26 = 5 ==> E
R + R = (18+18-1) mod 26 = 9 ==> I
A + E = (1+5-1) mod 26 = 5 ==> E
B + V = (2+22-1) mod 26 = 23 ==> W
I + I = (9+9-1) mod 26 = 17 ==> Q
G + G = (7+7-1) mod 26 = 14 ==> M
R + E = (18+5-1) mod 26 = 22 ==> V
A + N = (1+14-1) mod 26 = 14 ==> N
M + E = (13+5-1) mod 26 = 17 ==> Q
Jadi chipertextnya adalah:
KTGCSEZVXQVLRVKIMUGWHOBIYIREZTFPTOXEZGZTCMXCNRXQZTGOHORRNCHWGMKYNQYIPEIEWQMVNQ
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