Java 中使用 RSA 算法加密

发表于 2020-12-29 分类于 Java ， JavaClass 阅读次数： Valine：

RSA 介绍

RSA 加密算法是一种非对称加密算法。

RSA 是一对密钥。分别是公钥和私钥 , 这个公钥和私钥其实就是一组数字！其二进制位长度可以是 1024 位或者 2048 位。长度越长其加密强度越大，目前为止公之于众的能破解的最大长度为 768 位密钥，只要高于 768 位，相对就比较安全.

RSA 加密的方式

使用公钥加密的数据，利用私钥进行解密
使用私钥加密的数据，利用公钥进行解密

RSA 加密的缺点

由于 RSA 算法的原理都是大数计算，使得 RSA 最快的情况也比对称加密算法慢上好几倍。

使用 RSA

引入依赖：

<!-- https://mvnrepository.com/artifact/commons-codec/commons-codec -->
<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>1.15</version>
</dependency>

RSA 代码：

import org.apache.commons.codec.binary.Base64;

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

/**
 * Rsa 工具类，公钥私钥生成，加解密
 **/
public class RSAUtil {
    /**
     * 公钥解密
     *
     * @param publicKeyText 公钥
     * @param text 待解密的信息
     * @return /
     * @throws Exception /
     */
    public static String decryptByPublicKey(String publicKeyText, String text) throws Exception {
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(Base64.decodeBase64(text));
        return new String(result);
    }

    /**
     * 私钥加密
     *
     * @param privateKeyText 私钥
     * @param text 待加密的信息
     * @return /
     * @throws Exception /
     */
    public static String encryptByPrivateKey(String privateKeyText, String text) throws Exception {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(text.getBytes());
        return Base64.encodeBase64String(result);
    }

    /**
     * 私钥解密
     *
     * @param privateKeyText 私钥
     * @param text 待解密的文本
     * @return /
     * @throws Exception /
     */
    public static String decryptByPrivateKey(String privateKeyText, String text) throws Exception {
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(Base64.decodeBase64(text));
        return new String(result);
    }

    /**
     * 公钥加密
     *
     * @param publicKeyText 公钥
     * @param text 待加密的文本
     * @return /
     */
    public static String encryptByPublicKey(String publicKeyText, String text) throws Exception {
        X509EncodedKeySpec x509EncodedKeySpec2 = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec2);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(text.getBytes());
        return Base64.encodeBase64String(result);
    }

    /**
     * 构建RSA密钥对
     *
     * @return /
     * @throws NoSuchAlgorithmException /
     */
    public static RsaKeyPair generateKeyPair() throws NoSuchAlgorithmException {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(1024);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
        String publicKeyString = Base64.encodeBase64String(rsaPublicKey.getEncoded());
        String privateKeyString = Base64.encodeBase64String(rsaPrivateKey.getEncoded());
        return new RsaKeyPair(publicKeyString, privateKeyString);
    }


    /**
     * RSA密钥对对象
     */
    public static class RsaKeyPair {

        private final String publicKey;
        private final String privateKey;

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

        public String getPublicKey() {
            return publicKey;
        }

        public String getPrivateKey() {
            return privateKey;
        }

    }
}

测试 RSA

@Slf4j
public class RSAUtilTest {

    public static final String SRC = "123456";

    @Test
    public void testRSA(){
        try{
            RSAUtil.RsaKeyPair keyPair = RSAUtil.generateKeyPair();
            System.out.println("公钥：" + keyPair.getPublicKey());
            System.out.println("私钥：" + keyPair.getPrivateKey());
            System.out.println("\n");
            test1(keyPair);
            System.out.println("\n");
            test2(keyPair);
            System.out.println("\n");
        } catch (Exception e){
            log.error(e.getMessage(),e);
        }
    }

    /**
     * 公钥加密私钥解密
     */
    private static void test1(RSAUtil.RsaKeyPair keyPair) throws Exception {
        System.out.println("***************** 公钥加密私钥解密开始 *****************");
        String text1 = RSAUtil.encryptByPublicKey(keyPair.getPublicKey(), SRC);
        String text2 = RSAUtil.decryptByPrivateKey(keyPair.getPrivateKey(), text1);
        System.out.println("加密前：" + SRC);
        System.out.println("加密后：" + text1);
        System.out.println("解密后：" + text2);
        if (SRC.equals(text2)) {
            System.out.println("解密字符串和原始字符串一致，解密成功");
        } else {
            System.out.println("解密字符串和原始字符串不一致，解密失败");
        }
        System.out.println("***************** 公钥加密私钥解密结束 *****************");
    }

    /**
     * 私钥加密公钥解密
     * @throws Exception /
     */
    private static void test2(RSAUtil.RsaKeyPair keyPair) throws Exception {
        System.out.println("***************** 私钥加密公钥解密开始 *****************");
        String text1 = RSAUtil.encryptByPrivateKey(keyPair.getPrivateKey(), SRC);
        String text2 = RSAUtil.decryptByPublicKey(keyPair.getPublicKey(), text1);
        System.out.println("加密前：" + SRC);
        System.out.println("加密后：" + text1);
        System.out.println("解密后：" + text2);
        if (SRC.equals(text2)) {
            System.out.println("解密字符串和原始字符串一致，解密成功");
        } else {
            System.out.println("解密字符串和原始字符串不一致，解密失败");
        }
        System.out.println("***************** 私钥加密公钥解密结束 *****************");
    }
}

输入结果：

公钥：MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCL8TmwbG0Gi5fjs+0GI/vQnLfxzk66o44VurAQwvsL3EUbra4S/2gPn9vIBP9vW/FwUsRRHesqRVipS7I6idbUXIOH5g1i6qNborZOLb+lB2cXay1Sjc+sxEnAciVjQEdcKi56mvUuz6waJwzhB3HkruKcXJKAvux3WOECTLLgJQIDAQAB
私钥：MIICdgIBADANBgkqhkiG9w0BAQEFAASCAmAwggJcAgEAAoGBAIvxObBsbQaLl+Oz7QYj+9Cct/HOTrqjjhW6sBDC+wvcRRutrhL/aA+f28gE/29b8XBSxFEd6ypFWKlLsjqJ1tRcg4fmDWLqo1uitk4tv6UHZxdrLVKNz6zEScByJWNAR1wqLnqa9S7PrBonDOEHceSu4pxckoC+7HdY4QJMsuAlAgMBAAECgYAnUmXiY+UStMC+M72DPzMvwAmTwWOv3+s5wdZdL1x5TbCBgYDrR6cG1OVdw8G+mbgy1p7hKCX/H7M1BtcSyc56PQi77DvCaA3f/wr1i7jhDI+RFmL5unjKcuuyAfAKLxNxx16ErtxdKleygq645F48Qg8YIzF+9pqV1TPjk6P7tQJBAMJMTu+3nP+od92h78ekkkiC4KVOaI14wgvmSCj3qvBl1UGHgJZmmO2N6zp0HAwam1xc0PvQ9nV1tqbF5U+Uh4sCQQC4Yf+o67xiR9XCEEJyarEGQRie6tOEG0slg9WEDTrgEx3M8SfKdgjh3pzhpyLGf7CiwicnLiNfCB3o3l2m8q0PAkEAwM9Oye2wu7dnc6W+N6SlkZVm7kP31uQN1BcqZpUXqcW0MXoQ7a9UdPCPjIsqRgylPavRqwJ7gKZWofriCu2+7wJAIkMDkM4NOW4DyIXg8wXkUzcxbgZQu5Geyx/OQzV6JT0oIncFX9fDGsWU/VFjYuNDXVsaj2tBY11MwYLggC9D/QJAbgNEEDLpwOizVDWPy3qAgCifWEyg/FL5v9kVHo2+N19w0HlB0NMdYPVNEuPFxTxzzsnE087wEbhFHFjt9YjlkQ==


***************** 公钥加密私钥解密开始 *****************
加密前：123456
加密后：J8ov9OnSNuUL4biVYK09CZ1diwxXyiU1o/k8OzGkYy6MQ60yFNe3OaQ8Nu4kYaBhuZrd9jwEdl9EsUjwkwJ7U9yKe3U9lMcj/cEkrnNNEkDvKHBsq/NEIqrGOfW8+lfx/T6guN3KWALS6T0asBfE6uBrdRlIXhRrHyQ/XKRe/IA=
解密后：123456
解密字符串和原始字符串一致，解密成功
***************** 公钥加密私钥解密结束 *****************


***************** 私钥加密公钥解密开始 *****************
加密前：123456
加密后：Hw2vOZXe3nivbS1hR0dZhEtpSeaAfGrZiwOkgHNkPi1auNsgVM0MT7InaqdzOgu+f9AgNhOHhaNzROr4rI6RflsfEXeQp4gjR2v6Y0IJiT+djKIi8mF8esIEojXFwPqkNGFyzhS4dxP7P5voo5qLzU4RPVfmG0ldw+P5MA7p6tc=
解密后：123456
解密字符串和原始字符串一致，解密成功
***************** 私钥加密公钥解密结束 *****************