java 实现国密SM2、SM3、SM4

Java 中实现国密算法 SM2、SM3、SM4 可以使用 Bouncy Castle 密码库。Bouncy Castle 是一个流行的密码库，支持多种密码算法，包括国密算法。

以下是一个简单的示例，说明如何在 Java 中使用 Bouncy Castle 实现 SM2、SM3、SM4：

1. 添加 Bouncy Castle 依赖

在 Maven 项目中，可以在 pom.xml 文件中添加以下依赖：

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk15to18</artifactId>
    <version>1.68</version>
</dependency>

2. SM2 加密和解密示例

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.params.*;
import org.bouncycastle.crypto.signers.SM2Signer;
import org.bouncycastle.crypto.util.PrivateKeyFactory;
import org.bouncycastle.crypto.util.PublicKeyFactory;

import java.security.SecureRandom;

public class SM2Example {

    public static void main(String[] args) throws Exception {
        // 生成密钥对
        ECKeyPairGenerator ecKeyPairGenerator = new ECKeyPairGenerator();
        SecureRandom secureRandom = new SecureRandom();
        X9ECParameters ecParams = SECNamedCurves.getByName("sm2p256v1");
        ECDomainParameters ecDomainParameters = new ECDomainParameters(ecParams.getCurve(), ecParams.getG(), ecParams.getN(), ecParams.getH(), ecParams.getSeed());
        ECKeyGenerationParameters keyParams = new ECKeyGenerationParameters(ecDomainParameters, secureRandom);
        ecKeyPairGenerator.init(keyParams);
        AsymmetricCipherKeyPair keyPair = ecKeyPairGenerator.generateKeyPair();

        // 加密
        SM2Engine sm2Engine = new SM2Engine();
        CipherParameters publicKeyParameters = PublicKeyFactory.createKey(keyPair.getPublic().getEncoded());
        CipherParameters privateKeyParameters = PrivateKeyFactory.createKey(keyPair.getPrivate().getEncoded());
        sm2Engine.init(true, new ParametersWithRandom(publicKeyParameters, secureRandom));
        byte[] plainText = "hello world".getBytes();
        byte[] cipherText = sm2Engine.processBlock(plainText, 0, plainText.length);

        // 解密
        sm2Engine.init(false, privateKeyParameters);
        byte[] decryptedText = sm2Engine.processBlock(cipherText, 0, cipherText.length);
        System.out.println(new String(decryptedText));
    }
}

3. SM3 摘要示例

import org.bouncycastle.crypto.digests.SM3Digest;

public class SM3Example {

    public static void main(String[] args) {
        // 计算摘要
        byte[] input = "hello world".getBytes();
        SM3Digest digest = new SM3Digest();
        digest.update(input, 0, input.length);
        byte[] result = new byte[digest.getDigestSize()];
        digest.doFinal(result, 0);

        // 输出摘要
        System.out.println(bytesToHex(result));
    }

    private static final char[] HEX_ARRAY = "0123456789abcdef".toCharArray();

    public static String bytesToHex(byte[] bytes) {
        char[] hexChars = new char[bytes.length * 2];
        for (int i = 0; i < bytes.length; i++) {
            int v = bytes[i] & 0xFF;
            hexChars[i * 2] = HEX_ARRAY[v >>> 4];
            hexChars[i * 2 + 1] = HEX_ARRAY[v & 0x0F];
        }
        return new String(hexChars);
    }
}

4. SM4 加密和解密示例

import org.bouncycastle.crypto.engines.SM4Engine;
import org.bouncycastle.crypto.params.KeyParameter;

import java.security.SecureRandom;

public class SM4Example {

    public static void main(String[] args) {
        // 生成密钥
        SecureRandom secureRandom = new SecureRandom();
        byte[] key = new byte[16];
        secureRandom.nextBytes(key);
        KeyParameter keyParameter = new KeyParameter(key);

        // 加密
        SM4Engine sm4Engine = new SM4Engine();
        sm4Engine.init(true, keyParameter);
        byte[] plainText = "hello world".getBytes();
        byte[] cipherText = new byte[sm4Engine.getOutputSize(plainText.length)];
        int length = sm4Engine.processBytes(plainText, 0, plainText.length, cipherText, 0);
        sm4Engine.doFinal(cipherText, length);

        // 解密
        sm4Engine.init(false, keyParameter);
        byte[] decryptedText = new byte[sm4Engine.getOutputSize(cipherText.length)];
        length = sm4Engine.processBytes(cipherText, 0, cipherText.length, decryptedText, 0);
        sm4Engine.doFinal(decryptedText, length);
        System.out.println(new String(decryptedText));
    }
}

以上是实现 SM2、SM3、SM4 的简单示例，具体实现可以根据具体需求进行调整。