dhkx

Overview ¶

REQUIRE: go 1.16 or later

This is an implementation of Diffie-Hellman Key Exchange algorithm. The algorithm is used to establish a shared key between two communication peers without sharing secrete information.

Typical process:

First, Alice and Bob should agree on which group to use. If you are not sure, choose group 14. GetGroup() will return the desired group by a given id. GetGroup(0) will return a default group, which is usually safe enough to use this group. It is totally safe to share the group's information.

NOTE: The code below will skip error-checking part for the sake of simplicity.

Here is the code on Alice's side:

// Get a group. Use the default one would be enough.
g, _ := GetGroup(0)

// Generate a private key from the group.
// Use the default random number generator.
priv, _ := g.GeneratePrivateKey(nil)

// Get the public key from the private key.
pub := priv.Bytes()

// Send the public key to Bob.
Send("Bob", pub)

// Receive a slice of bytes from Bob, which contains Bob's public key
b := Recv("Bob")

// Recover Bob's public key
bobPubKey := NewPublicKey(b)

// Compute the key
k, _ := group.ComputeKey(bobPubKey, priv)

// Get the key in the form of []byte
key := k.Bytes()

Similarly, here is the code on Bob's side:

// Get a group. Use the default one would be enough.
g, _ := GetGroup(0)

// Generate a private key from the group.
// Use the default random number generator.
priv, _ := g.GeneratePrivateKey(nil)

// Get the public key from the private key.
pub := priv.Bytes()

// Receive a slice of bytes from Alice, which contains Alice's public key
a := Recv("Alice")

// Send the public key to Alice.
Send("Alice", pub)

// Recover Alice's public key
alicePubKey := NewPublicKey(a)

// Compute the key
k, _ := group.ComputeKey(alicePubKey, priv)

// Get the key in the form of []byte
key := k.Bytes()

To this point, the variables ”key” on both Alice and Bob side are same. It could be used as the secrete key for the later communication.