dh

dh is a simple, ready to use Diffie-Hellman-Ephemeral implementation written in golang using MODP groups as defined in RFC3526.

Example:

package main

import (
	"fmt"
	"reflect"
	"github.com/WolframAlph/dh"
)
    
func main() {
	alice := dh.New()
	bob := dh.New()
	
	aliceSecret := alice.ComputeSecret(bob.PublicKey)
	bobSecret := bob.ComputeSecret(alice.PublicKey)
	
	fmt.Println(reflect.DeepEqual(aliceSecret, bobSecret)) // true
}

Notes

You must use the same MODP group on both sides, or else you end up with non-matching keys. Group #14 is used by default. You can use different group from available (5, 14, 15, 16, 17, 18). Example using other group:

package main

import (
	"fmt"
	"reflect"
	"github.com/WolframAlph/dh"
)
    
func main() {
	modpGroup := 16
	alice := dh.New(modpGroup)
	bob := dh.New(modpGroup)
	
	aliceSecret := alice.ComputeSecret(bob.PublicKey)
	bobSecret := bob.ComputeSecret(alice.PublicKey)
	
	fmt.Println(reflect.DeepEqual(aliceSecret, bobSecret)) // true
}

Example using different groups:

package main

import (
	"fmt"
	"reflect"
	"github.com/WolframAlph/dh"
)
    
func main() {
	alice := dh.New(15)
	bob := dh.New(18)
	
	aliceSecret := alice.ComputeSecret(bob.PublicKey)
	bobSecret := bob.ComputeSecret(alice.PublicKey)
	
	fmt.Println(reflect.DeepEqual(aliceSecret, bobSecret)) // false
}