@wolf480pl Alice and Bob agree on a prime number, p, and a base, g, in advance. For our example, let's assume that p=23 and g=5. Alice chooses a secret integer a whose value is 6 and computes A = g^a mod p. In this example, A has the value of 8. Bob chooses a secret integer b whose value is 15 and computes B = g^b mod p. In this example, B has the value of 19. Alice sends A to Bob and Bob sends B to Alice. To obtain the shared secret, Alice computes s = B^a mod p. In this example, Alice obtains the value of s=2 To obtain the shared secret, Bob computes s = A^b mod p. In this example, Bob obtains the value of s=2. The algorithm is secure because the values of a and b, which are required to derive s are not transmitted across the wire at all.