Create diffieHellmanKeyExchange.go

Author: 0xbrayo

ciphers/diffieHellmanKeyExchange.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+)
+func main(){
+	bit:=30
+	/*
+	p and g are pre-agreed constants
+	that can be communicated over an insecure channel
+	p should ideally be a large prime number but any integer works
+	g should be a small integer, 2,3 works fine
+
+	PS: Note that the secret keys are never send over
+	the network
+	*/
+
+	p:=2+rand.Intn(1<<bit)
+	g:=2+rand.Intn(5)
+	
+	//Both parties choose a secret key
+	
+	AliceSecret := 1 + rand.Intn(1<<bit)
+	BobSecret := 1 + rand.Intn(1<<bit)
+	
+	fmt.Printf("Alice's secret key is: %v",AliceSecret)
+	fmt.Printf("Bob's secret key is: %v",BobSecret)
+	
+	//Both parties send ((g^secret_key)%p) 
+	//It's not possible to determine the secretkey from the value sent
+	
+	AliceSends :=modularExponentiation(g,AliceSecret,p)
+	BobSends :=modularExponentiation(g,BobSecret,p)
+
+	fmt.Printf("Alice sends to Bob: %v",AliceSends)
+	fmt.Printf("Bob sends to Alice: %v",BobSends)
+
+	//Both parties calculate the shared secret key from the value send
+	//(value_sent^secret_key)%p
+	//Both calculations end up with same value despite the different inputs
+	AliceComputes :=modularExponentiation(BobSends,AliceSecret,p)
+	BobComputes := modularExponentiation(AliceSends,BobSecret,p)
+
+	fmt.Printf("Alice Computes the shared secret key as: %v",AliceComputes)
+	fmt.Printf("Bob Computes the shared secret key as: %v",BobComputes)
+	
+	// simply confirms that the values are equal
+	if AliceComputes == BobComputes{
+		sharedKey:=AliceComputes
+		fmt.Println(" Voila, shared key is",sharedKey)
+	}
+
+	
+
+	
+}
+func modularExponentiation(b int, e int, mod int)int{
+	//runs in O(log(n)) where n = e
+	//uses exponentiation by squaring to speed up the process
+	if mod == 1{
+		return 0
+	}
+	r:=1
+	b = b % mod
+	for ;e>0;{
+		if e%2==1{
+			r=(r*b)%mod
+		}
+		e =e>>1
+		b = (b*b)%mod
+	}
+	return r
+}