Type: Substitution
(Note: it's formula for encryption is f
(x)=(ax+b)mod n, and for decryption
is f(y)=a^-1(y-b)mod n, where "a"
should be coprime of "n", "x" or "y"
corresponds on the position of the
letter in the alphabet (see rotation
code), and "b" is any value of input,
and mod n is the limit of rotation)
Example: (encryption)
Plaintext: AFFINE
a=5, b=8, n=26
F(x)=(ax+b)mod26
A=0, F(0)=(5(0)+8)mod26=8
F=5, F(5)=(5(5)+8)mod26=33
F=5, F(5)=(5(5)+8)mod26=33
I =8, F(8)=(5(8)+8)mod26=48
N=13, F(13)=(5(13)+8)mod26=73
E=4, F(4)=(5(4)+8)mod26=28
A=08=I
F=33=H
F=33=H
I =48=W
N=73=V
E=28=C
Ciphertext: IHHWVC
Example: (decryption)
Ciphertext: IHHWVC
a=5, b=8, n=26
F(y)=a^-1(y-b)mod n
I =08, f(8)=5^-1(8-8)mod26=0
H=33, f(33)=5^-1(33-8)mod26=5
H=33, f(33)=5^-1(33-8)mod26=5
W=48, f(48)=5^-1(48-8)mod26=8
V=73, f(73)=5^-1(73-8)mod26=13
C=28, f(28)=5^-1(28-8)mod26=4
I =0=A
H=5=F
H=5=F
W=8=I
V=13=N
C=5=E
Plaintext: AFFINE
