Create ECC.java

ECC.java

@@ -0,0 +1,59 @@
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import org.bouncycastle.jce.spec.ECParameterSpec;
+import org.bouncycastle.jce.spec.ECPrivateKeySpec;
+import org.bouncycastle.jce.spec.ECPublicKeySpec;
+import org.bouncycastle.math.ec.ECPoint;
+import org.bouncycastle.pqc.jcajce.provider.asymmetric.util.EC5Util;
+import javax.crypto.KeyAgreement;
+import javax.crypto.KeyGenerator;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.*;
+import java.security.spec.ECGenParameterSpec;
+import java.util.Base64;
+import java.util.Scanner;
+public class ECC {
+
+    static {
+        Security.addProvider(new BouncyCastleProvider());
+    }
+    public static KeyPair generateKeyPair() throws NoSuchAlgorithmException, InvalidAlgorithmParameterException {
+        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("EC");
+        ECGenParameterSpec ecSpec = new ECGenParameterSpec("secp256r1");
+        keyPairGenerator.initialize(ecSpec, new SecureRandom());
+        return keyPairGenerator.generateKeyPair();
+    }
+    public static byte[] performKeyAgreement(PrivateKey privateKey, PublicKey publicKey) throws Exception {
+        KeyAgreement keyAgreement = KeyAgreement.getInstance("ECDH");
+        keyAgreement.init(privateKey);
+        keyAgreement.doPhase(publicKey, true);
+        return keyAgreement.generateSecret();
+    }
+    public static String bytesToBase64(byte[] bytes) {
+        return Base64.getEncoder().encodeToString(bytes);
+    }
+
+    public static void main(String[] args) {
+        try {
+            Scanner scanner = new Scanner(System.in);
+
+            KeyPair aliceKeyPair = generateKeyPair();
+            PublicKey alicePublicKey = aliceKeyPair.getPublic();
+            PrivateKey alicePrivateKey = aliceKeyPair.getPrivate();
+
+            KeyPair bobKeyPair = generateKeyPair();
+            PublicKey bobPublicKey = bobKeyPair.getPublic();
+            PrivateKey bobPrivateKey = bobKeyPair.getPrivate();
+
+            byte[] aliceSharedSecret = performKeyAgreement(alicePrivateKey, bobPublicKey);
+            byte[] bobSharedSecret = performKeyAgreement(bobPrivateKey, alicePublicKey);
+
+            System.out.println("Alice's Public Key: " + bytesToBase64(alicePublicKey.getEncoded()));
+            System.out.println("Bob's Public Key: " + bytesToBase64(bobPublicKey.getEncoded()));
+            System.out.println("Alice's Shared Secret: " + bytesToBase64(aliceSharedSecret));
+            System.out.println("Bob's Shared Secret: " + bytesToBase64(bobSharedSecret));
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+}