在Android中使用sm2加密的代码

下面是一个使用Bouncy Castle库在Android中实现SM2算法加密的代码示例：

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.params.ParametersWithRandom;
import org.bouncycastle.crypto.signers.SM2Signer;
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.ECCurve;
import org.bouncycastle.math.ec.ECPoint;
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.Security;
import java.security.spec.InvalidKeySpecException;
import java.util.Arrays;

public class SM2Utils {
    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    // 生成SM2密钥对
    public static AsymmetricCipherKeyPair generateKeyPair() {
        ECKeyPairGenerator generator = new ECKeyPairGenerator();
        generator.init(new ParametersWithRandom(SM2Utils.getECParameterSpec(), new SecureRandom()));
        return generator.generateKeyPair();
    }

    // 获取SM2椭圆曲线参数
    public static ECParameterSpec getECParameterSpec() {
        BigInteger p = new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF", 16);
        BigInteger a = new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC", 16);
        BigInteger b = new BigInteger("28E9FA9E9D9F5E344D5A9E4BCF6509A7F39789F515AB8F92DDBCBD414D940E93", 16);
        BigInteger n = new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123", 16);
        BigInteger h = BigInteger.valueOf(1L);
        ECCurve curve = new ECCurve.Fp(p, a, b);
        ECPoint G = curve.decodePoint(Hex.decode("04"
                + "32C4AE2C1F1981195F9904466A39C9948FE30BBFF2660BE1712E06E7A21A7F6"
                + "1F3BDCB0728E9C9E9F9B2F5D0A97CC9C186FF06A96B9ACD3B4F1B34C3D4829E2"), curve.getEncoding());
        return new ECParameterSpec(curve, G, n, h);
    }

    // 将十六进制字符串转换为byte数组
    public static byte[] hexToByte(String hexStr) {
        if (hexStr == null || hexStr.length() < 1) {
            return null;
        }
        int len = hexStr.length() / 2;
        byte[] result = new byte[len];
        for (int i = 0; i < len; i++) {
            result[i] = (byte) Integer.parseInt(hexStr.substring(2 * i, 2 * i + 2), 16);
        }
        return result;
    }

    // 将byte数组转换为十六进制字符串
    public static String byteToHex(byte[] bytes) {
        StringBuilder hexStr = new StringBuilder();
        for (byte aByte : bytes) {
            String hex = Integer.toHexString(aByte & 0xFF);
            if (hex.length() == 1) {
                hexStr.append('0');
            }
            hexStr.append(hex);
        }
        return hexStr.toString();
    }

    // SM2加密
    public static byte[] sm2Encrypt(byte[] data, ECPublicKeyParameters publicKey) {
        SM2Cipher cipher = new SM2Cipher();
        cipher.init(true, new ParametersWithRandom(publicKey, new SecureRandom()));
        return cipher.processBlock(data, 0, data.length);
    }

    // SM2解密
    public static byte[] sm2Decrypt(byte[] cipherData, ECPrivateKeyParameters privateKey) {
        SM2Cipher cipher = new SM2Cipher();
        cipher.init(false, privateKey);
        return cipher.processBlock(cipherData, 0, cipherData.length);
    }

    // SM2签名
    public static byte[] sm2Sign(byte[] data, ECPrivateKeyParameters privateKey) throws UnsupportedEncodingException, NoSuchAlgorithmException {
        SM2Signer signer = new SM2Signer();
        signer.init(true, privateKey);
        signer.update(data, 0, data.length);
        return signer.generateSignature();
    }

    // SM2验签
    public static boolean sm2Verify(byte[] data, byte[] signData, ECPublicKeyParameters publicKey) throws UnsupportedEncodingException, NoSuchAlgorithmException {
        SM2Signer signer = new SM2Signer();
        signer.init(false, publicKey);
        signer.update(data, 0, data.length);
        return signer.verifySignature(signData);
    }
}

这个示例代码包括了SM2密钥对的生成、SM2加密、SM2解密、SM2签名和SM2验签等功能。你可以根据自己的需求来调用相应的方法。

需要注意的是，这段代码中使用的是Bouncy Castle库中的SM2Cipher类来实现SM2加密和解密。另外，由于SM2算法是一种国密算法，如果需要在对外公开的应用中使用SM2算法，需要获得相应的许可证。