Java Requires Chilkat v11.0.0+

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. Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Ecc;
import com.chilkatsoft.chilkat2.PrivateKey;
import com.chilkatsoft.chilkat2.Prng;
import com.chilkatsoft.chilkat2.PublicKey;

public class ChilkatExample {

    public static void main(String[] args) {
        // 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.
        // -----------------------------------------------------------------
        Prng prngClient = new Prng();
        Ecc eccClient = new Ecc();
        PrivateKey privKeyClient = new PrivateKey();
        try {
            eccClient.genKey("secp256r1", prngClient, privKeyClient);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        PublicKey pubKeyClient = new PublicKey();
        privKeyClient.toPublicKey(pubKeyClient);
        pubKeyClient.savePemFile(false, "qa_output/eccClientPub.pem");

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

        PublicKey pubKeyServer = new 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.
        PublicKey pubKeyFromServer = new PublicKey();
        pubKeyFromServer.loadFromFile("qa_output/eccServerPub.pem");
        String 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.
        PublicKey pubKeyFromClient = new PublicKey();
        pubKeyFromClient.loadFromFile("qa_output/eccClientPub.pem");
        String 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.
        // ---------------------------------------------------------
        System.out.println(sharedSecret1);
        System.out.println(sharedSecret2);
    }
}