Diffie-Hellman Key Exchange

diffie-hellman.txt

--- Step 1 - exchanged common values

Initial common values: 
p = 13 (prime number)
g = 7

--- Step 2 - Each user creates own secret number

Alice secret number:
a = 5

Bob secret number:
b = 8

Computed secret for Alice:
A = g^a mod p
A = 7^5 mod 13
A = 11

Computed secret for Bob:
B = g^a mod p
B = 7^5 mod 13
B = 3

--- Step 3 - Exchange computed secret to other user

Alice shared secret is:
S1 = B^a mod p
S1 = 3^5 mod 13
S1 = 9

Bob shared secret is:
S2 = A^b mod p
S2 = 11^8 mod 13
S2 = 9

--- Step 4 - Use symmetric key for encrypting

Symmetric key is established:
S1 = S2