java RSA 解密

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;

/**
 * @from fhadmin.cn
 * @description Rsa 工具類，公鑰私鑰生成，加解密
 * @date 2020-05-18
 **/
public class RsaUtils {

    private static final String SRC = "123456";

    public static void main(String[] args) throws Exception {
        System.out.println("\n");
        RsaKeyPair keyPair = generateKeyPair();
        System.out.println("公鑰：" + keyPair.getPublicKey());
        System.out.println("私鑰：" + keyPair.getPrivateKey());
        System.out.println("\n");
        test1(keyPair);
        System.out.println("\n");
        test2(keyPair);
        System.out.println("\n");
    }

    /**
     * 公鑰加密私鑰解密
     */
    private static void test1(RsaKeyPair keyPair) throws Exception {
        System.out.println("***************** 公鑰加密私鑰解密開始 *****************");
        String text1 = encryptByPublicKey(keyPair.getPublicKey(), RsaUtils.SRC);
        String text2 = decryptByPrivateKey(keyPair.getPrivateKey(), text1);
        System.out.println("加密前：" + RsaUtils.SRC);
        System.out.println("加密後：" + text1);
        System.out.println("解密後：" + text2);
        if (RsaUtils.SRC.equals(text2)) {
            System.out.println("解密字串和原始字串一致，解密成功");
        } else {
            System.out.println("解密字串和原始字串不一致，解密失敗");
        }
        System.out.println("***************** 公鑰加密私鑰解密結束 *****************");
    }

    /**
     * 私鑰加密公鑰解密
     * @throws Exception /
     */
    private static void test2(RsaKeyPair keyPair) throws Exception {
        System.out.println("***************** 私鑰加密公鑰解密開始 *****************");
        String text1 = encryptByPrivateKey(keyPair.getPrivateKey(), RsaUtils.SRC);
        String text2 = decryptByPublicKey(keyPair.getPublicKey(), text1);
        System.out.println("加密前：" + RsaUtils.SRC);
        System.out.println("加密後：" + text1);
        System.out.println("解密後：" + text2);
        if (RsaUtils.SRC.equals(text2)) {
            System.out.println("解密字串和原始字串一致，解密成功");
        } else {
            System.out.println("解密字串和原始字串不一致，解密失敗");
        }
        System.out.println("***************** 私鑰加密公鑰解密結束 *****************");
    }

    /**
     * 公鑰解密
     * @from fhadmin.cn
     * @param publicKeyText 公鑰
     * @param text 待解密的資訊
     * @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);
    }

    /**
     * 私鑰加密
     * @from fhadmin.cn
     * @param privateKeyText 私鑰
     * @param text 待加密的資訊
     * @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);
    }

    /**
     * 私鑰解密
     * @from fhadmin.cn
     * @param privateKeyText 私鑰
     * @param text 待解密的文字
     * @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);
    }

    /**
     * 公鑰加密
     * @from fhadmin.cn
     * @param publicKeyText 公鑰
     * @param text 待加密的文字
     * @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);
    }

    /**
     * 構建RSA金鑰對
     * @from fhadmin.cn
     * @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金鑰對物件
     */
    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;
        }

    }
}

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