一、ECC 椭圆曲线算法简介

ECC是椭圆曲线算法，其加密算法叫ECIES，签名算法叫ECDSA。JDK 并不支持 ECC 算法，可以引入 BouncyCastle 库使用。ECC算法相当耗费资源，如果单纯使用CPU进行加密/解密，效率低下。

引入 BouncyCastle 库

<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk15on</artifactId>
    <version>1.70</version>
</dependency>

<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.15</version>
</dependency>       

二、ECC 加解密代码实例

1.生成 ECC 密钥

由于 BouncyCastle 库对 keysize 有指定要求的，可以看 BouncyCastle 库中的类：KeyPairGeneratorSpi，从中可以看出支持的 keysize 就这么几个：192、239、256、224、384、521。

注意： 需要使用静态初始化块初始化 Provider，常量 EC_ALGORITHM = ”EC“ EC_PROVIDER = “BC”

static{
    try{
        Security.addProvider(new BouncyCastleProvider());
    }catch(Exception e){
        e.printStackTrace();
    }
}

• 密钥对对象

/**
 * @author: huangyibo
 * @Date: 2022/4/29 18:47
 * @Description: 非对称加密 密钥对对象
 */

public class RsaKeyPair {

    private String publicKey;

    private String privateKey;

    public RsaKeyPair(String publicKey, String privateKey) {
        this.publicKey = publicKey;
        this.privateKey = privateKey;
    }

    public String getPublicKey() {
        return publicKey;
    }

    public String getPrivateKey() {
        return privateKey;
    }
}

• 生成密钥对

/**
 * 生成密钥对
 *
 * @param keySize   密钥长度
 * @return          密钥对象
 */
public static RsaKeyPair generateEccKeyPair(int keySize) {
    try {
        // 获取指定算法的密钥对生成器
        KeyPairGenerator generator = KeyPairGenerator.getInstance(EC_ALGORITHM, EC_PROVIDER);
        // 初始化密钥对生成器（指定密钥长度, 使用默认的安全随机数源）
        generator.initialize(keySize);
        // 随机生成一对密钥（包含公钥和私钥）
        KeyPair keyPair = generator.generateKeyPair();
        PublicKey publicKey = keyPair.getPublic();
        PrivateKey privateKey = keyPair.getPrivate();
        String publicKeyString = Base64.encodeBase64String(publicKey.getEncoded());
        String privateKeyString = Base64.encodeBase64String(privateKey.getEncoded());
        return new RsaKeyPair(publicKeyString, privateKeyString);
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

2.ECC 加解密

ECIES_ALGORITHM = “ECIES”
EC_PROVIDER = “BC”

/**
 * ECC 加密
 *
 * @param publicKeyText 公钥
 * @param data      原文
 * @return　密文
 */
public static String eccEncrypt(String publicKeyText, String data) {
    try {
        X509EncodedKeySpec x509EncodedKeySpec2 = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance(EC_ALGORITHM);
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec2);
        Cipher cipher = Cipher.getInstance(ECIES_ALGORITHM, EC_PROVIDER);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(data.getBytes());
        return Base64.encodeBase64String(result);
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

/**
 * ECC 解密
 *
 * @param privateKeyText 私钥
 * @param data  　       密文
 * @return　原文
 */
public static String eccDecrypt(String privateKeyText, String data) {
    try {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance(EC_ALGORITHM);
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
        Cipher cipher = Cipher.getInstance(ECIES_ALGORITHM, EC_PROVIDER);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(Base64.decodeBase64(data));
        return new String(result);
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

3.测试代码

public static void main(String[] args) {
    // 测试文本 
    String plain = "12345678";

    // 生成密钥对
    RsaKeyPair rsaKeyPair = generateEccKeyPair(256);
    System.out.println("ECC公钥: "+rsaKeyPair.getPublicKey());
    System.out.println("ECC私钥: "+rsaKeyPair.getPrivateKey());

    // 加解密
    String encrypt = eccEncrypt(rsaKeyPair.getPublicKey(), plain);
    String decrypt = eccDecrypt(rsaKeyPair.getPrivateKey(), encrypt);
    System.err.println(plain.equals(decrypt));
}

三、ECC 签名验签代码实例

签名验签使用的密钥同上，签名算法使用：SHA256withECDSA 即 SIGNATURE = “SHA256withECDSA”。

1. ECC 签名验签

/**
 * 私钥签名
 *
 * @param privateKey 私钥
 * @param data       原文
 * @return 签名
 */
public static String eccSign(String privateKey, String data) {
    try {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));
        KeyFactory keyFactory = KeyFactory.getInstance(EC_ALGORITHM);
        PrivateKey key = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
        Signature signature = Signature.getInstance(SIGNATURE);
        signature.initSign(key);
        signature.update(data.getBytes());
        return new String(Base64.encodeBase64(signature.sign()));
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
}

/**
 * 公钥验签
 *
 * @param publicKey 公钥
 * @param srcData   原文
 * @param sign      签名
 * @return
 */
public static boolean eccVerify(String publicKey, String srcData, String sign) {
    try {
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
        KeyFactory keyFactory = KeyFactory.getInstance(EC_ALGORITHM);
        PublicKey key = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE);
        signature.initVerify(key);
        signature.update(srcData.getBytes());
        return signature.verify(Base64.decodeBase64(sign.getBytes()));
    } catch (Exception e) {
        e.printStackTrace();
    }
    return false;
}

2. 测试代码

public static void main(String[] args) {
    // 测试文本
    String plain = "12345678";

    // 生成密钥对
    RsaKeyPair rsaKeyPair = generateEccKeyPair(256);
    System.out.println("ECC公钥: "+rsaKeyPair.getPublicKey());
    System.out.println("ECC私钥: "+rsaKeyPair.getPrivateKey());

    // 签名验签
    String sign = eccSign(rsaKeyPair.getPrivateKey(), plain);
    boolean verify = eccVerify(rsaKeyPair.getPublicKey(), plain, sign);
    System.err.println(verify);
}

完整代码

import com.yibo.dsa.RsaKeyPair;
import org.apache.commons.codec.binary.Base64;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * @author: huangyibo
 * @Date: 2022/4/29 10:31
 * @Description:
 */

public class ECCUtils {

    private static final String EC_ALGORITHM = "EC";

    private static final String EC_PROVIDER = "BC";

    private static final String ECIES_ALGORITHM = "ECIES";

    private static final String SIGNATURE = "SHA256withECDSA";

    static{
        try{
            Security.addProvider(new BouncyCastleProvider());
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    /**
     * 生成密钥对
     *
     * @param keySize   密钥长度
     * @return          密钥对象
     */
    public static RsaKeyPair generateEccKeyPair(int keySize) {
        try {
            // 获取指定算法的密钥对生成器
            KeyPairGenerator generator = KeyPairGenerator.getInstance(EC_ALGORITHM, EC_PROVIDER);
            // 初始化密钥对生成器（指定密钥长度, 使用默认的安全随机数源）
            generator.initialize(keySize);
            // 随机生成一对密钥（包含公钥和私钥）
            KeyPair keyPair = generator.generateKeyPair();
            PublicKey publicKey = keyPair.getPublic();
            PrivateKey privateKey = keyPair.getPrivate();
            String publicKeyString = Base64.encodeBase64String(publicKey.getEncoded());
            String privateKeyString = Base64.encodeBase64String(privateKey.getEncoded());
            return new RsaKeyPair(publicKeyString, privateKeyString);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * ECC 加密
     *
     * @param publicKeyText 公钥
     * @param data      原文
     * @return　密文
     */
    public static String eccEncrypt(String publicKeyText, String data) {
        try {
            X509EncodedKeySpec x509EncodedKeySpec2 = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));
            KeyFactory keyFactory = KeyFactory.getInstance(EC_ALGORITHM);
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec2);
            Cipher cipher = Cipher.getInstance(ECIES_ALGORITHM, EC_PROVIDER);
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            byte[] result = cipher.doFinal(data.getBytes());
            return Base64.encodeBase64String(result);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * ECC 解密
     *
     * @param privateKeyText 私钥
     * @param data  　       密文
     * @return　原文
     */
    public static String eccDecrypt(String privateKeyText, String data) {
        try {
            PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));
            KeyFactory keyFactory = KeyFactory.getInstance(EC_ALGORITHM);
            PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
            Cipher cipher = Cipher.getInstance(ECIES_ALGORITHM, EC_PROVIDER);
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte[] result = cipher.doFinal(Base64.decodeBase64(data));
            return new String(result);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 私钥签名
     *
     * @param privateKey 私钥
     * @param data       原文
     * @return 签名
     */
    public static String eccSign(String privateKey, String data) {
        try {
            PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));
            KeyFactory keyFactory = KeyFactory.getInstance(EC_ALGORITHM);
            PrivateKey key = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
            Signature signature = Signature.getInstance(SIGNATURE);
            signature.initSign(key);
            signature.update(data.getBytes());
            return new String(Base64.encodeBase64(signature.sign()));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 公钥验签
     *
     * @param publicKey 公钥
     * @param srcData   原文
     * @param sign      签名
     * @return
     */
    public static boolean eccVerify(String publicKey, String srcData, String sign) {
        try {
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
            KeyFactory keyFactory = KeyFactory.getInstance(EC_ALGORITHM);
            PublicKey key = keyFactory.generatePublic(keySpec);
            Signature signature = Signature.getInstance(SIGNATURE);
            signature.initVerify(key);
            signature.update(srcData.getBytes());
            return signature.verify(Base64.decodeBase64(sign.getBytes()));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    public static void main(String[] args) {
        // 测试文本
        String plain = "12345678";

        // 生成密钥对
        RsaKeyPair rsaKeyPair = generateEccKeyPair(256);
        System.out.println("ECC公钥: "+rsaKeyPair.getPublicKey());
        System.out.println("ECC私钥: "+rsaKeyPair.getPrivateKey());

        // 加解密
        String encrypt = eccEncrypt(rsaKeyPair.getPublicKey(), plain);
        String decrypt = eccDecrypt(rsaKeyPair.getPrivateKey(), encrypt);
        System.err.println(plain.equals(decrypt));

        // 签名验签
        String sign = eccSign(rsaKeyPair.getPrivateKey(), plain);
        boolean verify = eccVerify(rsaKeyPair.getPublicKey(), plain, sign);
        System.err.println(verify);
    }
}

参考：
https://blog.csdn.net/yuanjian0814/article/details/109815473