added Diffie-Hellman. Started impl ECC

dh/dh.go

@@ -0,0 +1 @@
+package dh

dh/dh_test.go

@@ -0,0 +1,45 @@
+package dh
+
+import (
+	"crypto/rand"
+	"math/big"
+	"testing"
+)
+
+const (
+	bits = 2048
+)
+
+func TestDiffieHellman(t *testing.T) {
+	p, err := rand.Prime(rand.Reader, bits/2)
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+	g, err := rand.Prime(rand.Reader, bits/2)
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+
+	max, err := rand.Prime(rand.Reader, bits/2)
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+	a, err := rand.Int(rand.Reader, max)
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+	b, err := rand.Int(rand.Reader, max)
+	if err != nil {
+		t.Errorf(err.Error())
+	}
+
+	A := new(big.Int).Exp(g, a, p)
+	B := new(big.Int).Exp(g, b, p)
+
+	sA := new(big.Int).Exp(B, a, p)
+	sB := new(big.Int).Exp(A, b, p)
+
+	if sA.Int64() != sB.Int64() {
+		t.Errorf("secret not equal")
+	}
+}