生成一个完整的：DH秘钥交换实现 Java代码

Diffie-Hellman（DH）密钥交换是一种非对称加密技术，用于两个通信方在不共享预先秘密的情况下建立共享密钥。以下是一个简单的Java实现，使用`java.math.BigInteger`和`javax.crypto.interfaces.DHParameterSpec`：

import javax.crypto.spec.DHParameterSpec;
import java.math.BigInteger;

public class DHKeyExchangeExample {
    private static final String MODULUS = "FFFFFFFFFFFFFFFFC90F892B0DA4A2FC000756AC0710657B8E30038A8530FA773BBC9AB8514" +
            "5EBFE70C5D8D31E0FFFA590C845BFEA3C14DBCF87DE8AECC1CBB82B5E1DBF1055ED"
            // You can replace this with a larger prime number from RFC 3526
    ;
    
    public static void main(String[] args) throws Exception {
        BigInteger p = new BigInteger(MODULUS, 16);
        // Generate or load DH parameters (from a trusted source)
        DHParameterSpec dhParams = new DHParameterSpec(p, 2); // 2 is the generator (RFC 3526 uses 2)

        // Alice and Bob agree on these parameters
        Alice alice = new Alice(dhParams);
        Bob bob = new Bob(dhParams);

        BigInteger aliceSecret = alice.generatePrivateKey();
        BigInteger bobSecret = bob.generatePrivateKey();

        // Alice computes shared key (Bob's public key)
        BigInteger sharedKeyAlice = alice.exchange(bob.getPublicKey());
        // Bob computes shared key (Alice's public key)
        BigInteger sharedKeyBob = bob.exchange(alice.getPublicKey());

        // Both should get the same result
        System.out.printf("Shared secret: %s%n", sharedKeyAlice.equals(sharedKeyBob) ? "Match" : "Mismatch");
    }

    static class Alice {
        private final DHParameterSpec params;

        public Alice(DHParameterSpec params) {
            this.params = params;
        }

        public BigInteger generatePrivateKey() {
            return new BigInteger(130, SecureRandom.getInstanceStrong()); // Just an example; use proper random generation in practice
        }

        public BigInteger getPublicKey() {
            return params.getP().modPow(getPrivateKey(), params.getG());
        }

        BigInteger exchange(BigInteger remotePublicKey) {
            return remotePublicKey.modPow(getPrivateKey(), params.getP());
        }
    }

    static class Bob {
        private final DHParameterSpec params;

        public Bob(DHParameterSpec params) {
            this.params = params;
        }

        // Similar to Alice, generates a random private key and computes the public key
        // ... (omitted for brevity)
    }
}

在这个例子中，Alice和Bob各自生成随机私钥，通过公钥交换计算出相同的共享密钥。请注意，实际应用中需要更安全的方式来生成随机数，并从可信源获取DH参数。