Node.js

How to Generate an Elliptic Curve Shared Secret

See more ECC Examples

Demonstrates how to generate an ECC (Elliptic Curve Cryptography) shared secret. Imagine a cilent has one ECC private key, the server has another. A shared secret is computed by each side providing it's public key to the other. The private keys are kept private. Node.js

NODEJS_PRELUDE

function chilkatExample() {

    var success = false;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    //  This example includes both client-side and server-side code.
    //  Each code segment is marked as client-side or server-side.
    //  Imagine these segments are running on separate computers...

    //  -----------------------------------------------------------------
    //  (Client-Side) Generate an ECC key, save the public part to a file.
    //  -----------------------------------------------------------------
    var prngClient = new chilkat.Prng();
    var eccClient = new chilkat.Ecc();
    var privKeyClient = new chilkat.PrivateKey();
    success = eccClient.GenKey("secp256r1",prngClient,privKeyClient);
    if (success == false) {
        console.log(eccClient.LastErrorText);
        return;
    }

    var pubKeyClient = new chilkat.PublicKey();
    privKeyClient.ToPublicKey(pubKeyClient);
    pubKeyClient.SavePemFile(false,"qa_output/eccClientPub.pem");

    //  -----------------------------------------------------------------
    //  (Server-Side) Generate an ECC key, save the public part to a file.
    //  -----------------------------------------------------------------
    var prngServer = new chilkat.Prng();
    var eccServer = new chilkat.Ecc();
    var privKeyServer = new chilkat.PrivateKey();
    eccServer.GenKey("secp256r1",prngServer,privKeyServer);

    var pubKeyServer = new chilkat.PublicKey();
    privKeyServer.ToPublicKey(pubKeyServer);
    pubKeyServer.SavePemFile(false,"qa_output/eccServerPub.pem");

    //  -----------------------------------------------------------------
    //  (Client-Side) Generate the shared secret using our private key, and the other's public key.
    //  -----------------------------------------------------------------

    //  Imagine that the server sent the public key PEM to the client.
    //  (This is simulated by loading the server's public key from the file.
    var pubKeyFromServer = new chilkat.PublicKey();
    pubKeyFromServer.LoadFromFile("qa_output/eccServerPub.pem");
    var sharedSecret1 = eccClient.SharedSecretENC(privKeyClient,pubKeyFromServer,"base64");

    //  -----------------------------------------------------------------
    //  (Server-Side) Generate the shared secret using our private key, and the other's public key.
    //  -----------------------------------------------------------------

    //  Imagine that the client sent the public key PEM to the server.
    //  (This is simulated by loading the client's public key from the file.
    var pubKeyFromClient = new chilkat.PublicKey();
    pubKeyFromClient.LoadFromFile("qa_output/eccClientPub.pem");
    var sharedSecret2 = eccServer.SharedSecretENC(privKeyServer,pubKeyFromClient,"base64");

    //  ---------------------------------------------------------
    //  Examine the shared secrets.  They should be the same.
    //  Both sides now have a secret that only they know.
    //  ---------------------------------------------------------
    console.log(sharedSecret1);
    console.log(sharedSecret2);

}

chilkatExample();