乾貨

package com.hht.exchange.utils;

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

public class RSAUtils {

     /**
      * 預設的2048位金鑰對,可處理245個位元組(81個漢字)的資料
      */
     public static
 
 String PRIVATE_KEY = "MIIEv***XFu4=";

    public static String PUBLIC_KEY = "MIIB***DAQAB";

     /**
      * 字符集
      */
     public static String CHARSET = "utf-8";

     /**
      * 簽名演算法
      */
     public static final String SIGNATURE_INSTANCE = "SHA1WithRSA";

    /**
     * 生成金鑰對
     * @param keyLength
     * @return
     * @throws Exception
     */
 

    public static KeyPair getKeyPair(int keyLength) throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(keyLength);
        return keyPairGenerator.generateKeyPair();
    }

    /**
     * 公鑰字串轉PublicKey例項
     * @param publicKey
     * @return
     * @throws Exception
     */
 

    public static PublicKey getPublicKey(String publicKey) throws Exception {
         byte[] publicKeyBytes = Base64.getDecoder().decode(publicKey.getBytes());
         X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyBytes);
         KeyFactory keyFactory = KeyFactory.getInstance("RSA");
         return keyFactory.generatePublic(keySpec);
     }

    /**
     * 私鑰字串轉PrivateKey例項
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static PrivateKey getPrivateKey(String privateKey) throws Exception {
         byte[] privateKeyBytes = Base64.getDecoder().decode(privateKey.getBytes());
         PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKeyBytes);
         KeyFactory keyFactory = KeyFactory.getInstance("RSA");
         return keyFactory.generatePrivate(keySpec);
     }

    /**
     * 公鑰加密
     * @param content
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] content, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(content);
    }

    public static byte[] encryptByPublicKey(byte[] content) throws Exception {
        return encryptByPublicKey(content, getPublicKey(PUBLIC_KEY));
    }

    public static String encryptByPublicKey(String content, String publicKey) throws Exception {
       return new String(Base64.getEncoder().encode(encryptByPublicKey(content.getBytes(CHARSET), getPublicKey(publicKey))));

    }

    public static String encryptByPublicKey(String content) throws Exception {
        return new String(Base64.getEncoder().encode(encryptByPublicKey(content.getBytes(CHARSET))));
    }

    /**
     * 私鑰解密
     * @param content
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] content, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(content);
    }

    public static byte[] decryptByPrivateKey(byte[] content) throws Exception {
        return decryptByPrivateKey(content, getPrivateKey(PRIVATE_KEY));
    }

    public static String decryptByPrivateKey(String content, String privateKey) throws Exception {
        return new String(decryptByPrivateKey(Base64.getDecoder().decode(content), getPrivateKey(privateKey)), CHARSET);

    }

    public static String decryptByPrivateKey(String content) throws Exception {
        return new String(decryptByPrivateKey(Base64.getDecoder().decode(content)), CHARSET);
    }

    /**
     * 私鑰加密
     * @param content
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] content, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        return cipher.doFinal(content);
    }

    public static byte[] encryptByPrivateKey(byte[] content) throws Exception {
        return encryptByPrivateKey(content, getPrivateKey(PRIVATE_KEY));
    }

    public static String encryptByPrivateKey(String content, String privateKey) throws Exception {
        return new String(encryptByPrivateKey(content.getBytes(CHARSET), getPrivateKey(privateKey)), CHARSET);
    }

    public static String encryptByPrivateKey(String content) throws Exception {
        return new String(encryptByPrivateKey(content.getBytes(CHARSET)), CHARSET);
    }

    /**
     * 公鑰解密
     * @param content
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static byte[] decrypByPublicKey(byte[] content, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        return cipher.doFinal(content);
    }

    public static byte[] decrypByPublicKey(byte[] content) throws Exception {
        return decrypByPublicKey(content, getPublicKey(PUBLIC_KEY));
    }

    public static String decrypByPublicKey(String content, String publicKey) throws Exception {
        return new String(decrypByPublicKey(Base64.getDecoder().decode(content), getPublicKey(publicKey)), CHARSET);

    }

    public static String decrypByPublicKey(String content) throws Exception {
        return new String(decrypByPublicKey(Base64.getDecoder().decode(content)), CHARSET);
    }

    /**
     * 簽名
     * @param content
     * @param privateKey
     * @return
     * @throws Exception
     */
    public static byte[] sign(byte[] content, PrivateKey privateKey) throws Exception {
        Signature signature = Signature.getInstance(SIGNATURE_INSTANCE);
        signature.initSign(privateKey);
        signature.update(content);
        return signature.sign();
    }

    public static byte[] sign(byte[] content) throws Exception {
        return sign(content, getPrivateKey(PRIVATE_KEY));
    }

    public static String sign(String content, String privateKey) throws Exception {
        return new String(Base64.getEncoder().encode(sign(content.getBytes(CHARSET), getPrivateKey(privateKey))), CHARSET);
    }

    public static String sign(String content) throws Exception {
        return new String(Base64.getEncoder().encode(sign(content.getBytes(CHARSET))), CHARSET);
    }

    /**
     * 驗籤
     * @param content
     * @param sign
     * @param publicKey
     * @return
     * @throws Exception
     */
    public static boolean verify(byte[] content, byte[] sign,  PublicKey publicKey) throws Exception {
        Signature signature = Signature.getInstance(SIGNATURE_INSTANCE);
        signature.initVerify(publicKey);
        signature.update(content);
        return signature.verify(sign);
    }

    public static boolean verify(byte[] content, byte[] sign) throws Exception {
        return verify(content, sign, getPublicKey(PUBLIC_KEY));
    }

    public static boolean verify(String content, String sign, String publicKey) throws Exception {
        return verify(content.getBytes(CHARSET), Base64.getDecoder().decode(sign), getPublicKey(publicKey));
    }

    public static boolean verify(String content, String sign) throws Exception {
        return verify(content.getBytes(CHARSET), Base64.getDecoder().decode(sign), getPublicKey(PUBLIC_KEY));
    }
}

預設的金鑰對可以用這段程式碼計算:

    @Test
    public void testGetKeyPair() {
        try {
            KeyPair keyPair = RSAUtils.getKeyPair(1024);
            PublicKey publicKey = keyPair.getPublic();
            PrivateKey privateKey = keyPair.getPrivate();
            System.out.println(new String(Base64.getEncoder().encode(publicKey.getEncoded())));
            // MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDffzKfmLgZWc1cp0kMwky0Yd4upchGbKRS5a9L2Imw1m0BVpE1Vcg0i9tnBCYzRmuToeq+m30SQhMK+FvICMMvRX9zMyvvf50jMIV78xB6UBWJd5EIFwwPP900I/sSWE3fT09BwVDNP1ILPAAN2ZfjbUkDrIFPra8WKjVc5bTlWwIDAQAB
            System.out.println(new String(Base64.getEncoder().encode(privateKey.getEncoded())));
            // 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
        } catch (Exception e) {
            e.printStackTrace();
        }
    }