The Modular Arithmetic class is a static class with methods useful in doing modular arithmetic. These include finding gcds, factoring modulo a number, computing exponents, finding inverses, etc.

gcd(a,b)
extendedEuclidian(xy[], a, b)
solve(a,c,n)
inverseMod(a,n)

Cipher Implementations:

Cipher Implementation: Caesar Cipher

The Caesar class implements the Caesar cipher, which is a simple rotation (ROT) cipher with a key between 0 and 25.

Cipher Implementation: Affine Cipher

The Affine class implements the Affine cipher, which implements both a multiplicative and an additive shift. The key has two parts.

If the letters are indexed from 0 to 25, they are shifted according to the formula: formula:

a x + b (mod 26)

where a is the first part of the key and b is the second part of the key. This requires that gcd(a,26) = 1.