Modular Multiplicative Inverse

Giriş

Açıklaması şöyle

1. M seçimi : Pick a modulus M, which should be one more than the maximum value the field can hold.

In this case, since the max is 255, we choose M = 256.

2. P seçimi : Pick a number P that’s coprime with M (i.e., they share no common factors except 1).

Let’s go with P = 9.

3. Q seçimi : Now, a number Q such that (P × Q) mod M = 1. Q = 57

Örnek

encoded_value = (original_value * P) % M

original_value = (encoded_value * Q) % M

195 değeri için

219= (195 * 9) % 256

195 = (219 * 57) % 256