Add DHKE

dhke.py

@@ -0,0 +1,67 @@
+#!/usr/bin/env python
+
+import random
+
+from rich.traceback import install
+install()
+
+RAND_SIZE = 16
+MOD_SIZE = 10
+GEN_SIZE = 8
+
+def isPrime(x):
+    count = 0
+    for i in range(int(x/2)):
+        if x % (i+1) == 0:
+            count = count+1
+    return count == 1
+
+
+# Bad idea except for toy examples
+PRIMES = [i for i in range(0, 2**MOD_SIZE) if isPrime(i)]
+
+class Party():
+    def __init__(self, name, g, p):
+        self.name = name
+        self.random_num = random.randint(0, 2**RAND_SIZE)
+        self.g = g
+        self.p = p
+
+    def secret_ingredient(self):
+        return self.g**self.random_num % self.p
+
+    def secret(self, ingredient):
+        self.secret = ingredient**self.random_num % self.p
+
+
+class Alice(Party):
+    def __init__(self, g, p):
+        Party.__init__(self, "Alice", g, p)
+
+class Bob(Party):
+    def __init__(self, g, p):
+        Party.__init__(self, "Bob", g, p)
+
+#
+# Diffie-Hellman Key Exchange
+#
+
+# 1: Choose generator and prime modulus publicly
+g = random.randint(0, 2**GEN_SIZE)
+p = random.choice(PRIMES)
+
+# 2: Choose secret random numbers
+alice = Alice(g, p)
+bob = Bob(g, p)
+
+# 3: Calculate secret ingredient (public)
+a = alice.secret_ingredient()
+b = bob.secret_ingredient()
+
+# 4: Calculate shared secret
+alice.secret(b)
+bob.secret(a)
+
+print(f"Chosen g = {g} and p = {p}")
+print(f"Exchanged a = {a} and b = {b}")
+print(f"Calculated secrets s = {alice.secret} and s = {bob.secret}")