This is a linear cipher. It allows you to select values for a and b
and enciphers using C = aP+b (mod 26). It then allows you to decipher as well
by solving the linear congruence for P in terms of C and using the resulting coefficients a' and b'.

Choose the value of a: 1 3 5 7 9 11 15 17 19 21 23 25

Choose the value of b: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Enter plain text to be encrypted below: