keyPair.getPublic()怎么获取hex字符串的公钥么

可以使用Java中的BigInteger和Hex类将公钥转换为Hex字符串。具体代码如下：

PublicKey publicKey = keyPair.getPublic();
byte[] publicKeyBytes = publicKey.getEncoded();
String publicKeyHex = String.format("%0" + (publicKeyBytes.length*2) + "X", new BigInteger(1, publicKeyBytes));

其中，`publicKey.getEncoded()`方法将公钥转换为字节数组，然后使用BigInteger将字节数组转换为16进制字符串。注意，由于BigInteger默认会忽略前导0，因此需要使用String.format()方法补全前导0。

希望能对你有所帮助。

相关问题

用sm2公钥加密数据的Java代码

下面是用 Java 实现使用 SM2 公钥加密数据的代码示例：

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.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Hex;

import java.security.Security;

public class SM2EncryptionDemo {

    public static void main(String[] args) throws Exception {
        Security.addProvider(new BouncyCastleProvider());

        // 生成 SM2 密钥对
        ECKeyPairGenerator gen = new ECKeyPairGenerator();
        gen.initialize(CryptoUtils.getSM2Params());
        AsymmetricCipherKeyPair keyPair = gen.generateKeyPair();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();

        // 待加密的数据
        String plainText = "Hello, world!";
        byte[] plainBytes = plainText.getBytes("UTF-8");

        // 使用公钥加密数据
        byte[] cipherBytes = CryptoUtils.SM2Encrypt(publicKey, plainBytes);

        // 打印加密结果
        System.out.println("Plain text: " + plainText);
        System.out.println("Cipher text: " + Hex.toHexString(cipherBytes));
    }
}

其中，`CryptoUtils` 中的 `SM2Encrypt` 方法用于使用 SM2 公钥加密数据，代码如下：

import org.bouncycastle.crypto.InvalidCipherTextException;
import org.bouncycastle.crypto.engines.SM2Engine;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.params.ParametersWithRandom;

import java.security.SecureRandom;

public class CryptoUtils {

    // 获取 SM2 参数
    public static SM2Parameters getSM2Params() {
        return SM2Util.getDefaultParameters();
    }

    // 使用 SM2 公钥加密数据
    public static byte[] SM2Encrypt(ECPublicKeyParameters publicKey, byte[] plainText) throws InvalidCipherTextException {
        SM2Engine engine = new SM2Engine();
        ParametersWithRandom params = new ParametersWithRandom(publicKey, new SecureRandom());
        engine.init(true, params);
        return engine.processBlock(plainText, 0, plainText.length);
    }
}

需要注意的是，上述代码中使用的 `SM2Util` 是我自己封装的一个工具类，用于获取 SM2 的默认参数，代码如下：

import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.params.ECDomainParameters;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import java.math.BigInteger;
import java.security.Security;

public class SM2Util {

    // 获取 SM2 默认参数
    public static SM2Parameters getDefaultParameters() {
        Security.addProvider(new BouncyCastleProvider());
        ECDomainParameters ecParams = new ECDomainParameters(
                new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFF", 16), // p
                new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00000000FFFFFFFFFFFFFFFC", 16), // a
                new BigInteger("28E9FA9E9D9F5E34411C1D2F8F98F06F1ECF40D9BFD648968B3E23FB4C776293", 16), // b
                new BigInteger("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123", 16), // n
                new BigInteger("1", 16) // h
        );
        ECKeyPairGenerator gen = new ECKeyPairGenerator();
        gen.initialize(ecParams);
        AsymmetricCipherKeyPair keyPair = gen.generateKeyPair();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();
        return new SM2Parameters(ecParams, publicKey, privateKey);
    }

}

java如何生成sm2公钥pem文件

要生成SM2公钥PEM文件，需要使用Java的Bouncy Castle库。下面是一个示例代码，可以生成SM2公钥PEM文件：

import java.io.FileWriter;
 java.io.IOException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.Security;

import org.bouncycastle.asn1.x500.X500Name;
import org.bouncycastle.cert.X509v3CertificateBuilder;
import org.bouncycastle.cert.jcajce.JcaX509CertificateConverter;
import org.bouncycastle.cert.jcajce.JcaX509v3CertificateBuilder;
import org.bouncycastle.crypto.generators.ECKeyPairGenerator;
import org.bouncycastle.crypto.params.ECKeyGenerationParameters;
import org.bouncycastle.crypto.params.ECPrivateKeyParameters;
import org.bouncycastle.crypto.params.ECPublicKeyParameters;
import org.bouncycastle.crypto.util.PrivateKeyFactory;
import org.bouncycastle.crypto.util.SubjectPublicKeyInfoFactory;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Hex;

public class SM2KeyPairGenerator {

    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    public static void main(String[] args) throws Exception {

        // Generate SM2 key pair
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("EC", "BC");
        ECKeyGenerationParameters ecParams = new ECKeyGenerationParameters(SM2Curve.SM2P256V1_DOMAIN_PARAMS, null);
        ECKeyPairGenerator keyPairGen = new ECKeyPairGenerator();
        keyPairGen.init(ecParams);
        keyPairGenerator.initialize(ecParams);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        ECPublicKeyParameters publicKey = (ECPublicKeyParameters) keyPair.getPublic();
        ECPrivateKeyParameters privateKey = (ECPrivateKeyParameters) keyPair.getPrivate();

        // Output public key in PEM format
        String pemFileName = "public_key.pem";
        FileWriter pemFileWriter = new FileWriter(pemFileName);
        pemFileWriter.write("-----BEGIN PUBLIC KEY-----\n");
        byte[] publicKeyBytes = SubjectPublicKeyInfoFactory.createSubjectPublicKeyInfo(publicKey).getEncoded();
        pemFileWriter.write(new String(Hex.encode(publicKeyBytes)).toUpperCase());
        pemFileWriter.write("\n-----END PUBLIC KEY-----\n");
        pemFileWriter.close();

        System.out.println("Public key generated: " + pemFileName);
    }
}

在上面的代码中，我们首先生成了一个SM2密钥对，然后将公钥转换为PEM格式并将其写入文件。这里我们使用了Bouncy Castle库提供的SubjectPublicKeyInfoFactory类来将ECPublicKeyParameters对象转换为SubjectPublicKeyInfo对象，然后将其编码为DER格式，最后将DER格式的公钥用Hex编码并写入PEM文件中。