網路請求的資料需要加密，伺服器給的他們那一套在Android一直報錯，自己寫了一個；

package com.cc.common.util;


import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

/**
 * RSA加解密工具類
 */
public class RSAUtils {
    //公鑰加密
    public static String encrypt(String content, PublicKey publicKey) {
        try{
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");//java預設"RSA"="RSA/ECB/PKCS1Padding"
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            byte[] output = cipher.doFinal(content.getBytes());
            BASE64Encoder encoder = new BASE64Encoder();
            return encoder.encode(output);
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }

    //公鑰加密
    public static byte[] encrypt(byte[] content, PublicKey publicKey) {
        try{
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");//java預設"RSA"="RSA/ECB/PKCS1Padding"
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return  cipher.doFinal(content);
        }catch (Exception e){
            e.printStackTrace();
        }
        return null;
    }

    //私鑰解密
    public static byte[] decrypt(byte[] content, PrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            return cipher.doFinal(content);
        } catch (Exception e){
            e.printStackTrace();
            return null;
        }
    }
    //私鑰解密
    public static String decrypt(String content, PrivateKey privateKey) {
        try {
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            byte [] b = cipher.doFinal(content.getBytes());
            BASE64Encoder encoder = new BASE64Encoder();
            return encoder.encode(b);
        } catch (Exception e){
            e.printStackTrace();
            return null;
        }
    }

    /**
     * String轉公鑰PublicKey
     * @param key
     * @return
     * @throws Exception
     */
    public static PublicKey getPublicKey(String key) throws Exception {
        byte[] keyBytes;
        keyBytes = (new BASE64Decoder()).decodeBuffer(key);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
        return publicKey;
    }

    /**
     * String轉私鑰PrivateKey
     * @param key
     * @return
     * @throws Exception
     */
    public static PrivateKey getPrivateKey(String key) throws Exception {
        byte[] keyBytes;
        keyBytes = (new BASE64Decoder()).decodeBuffer(key);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }
}
 

如果你的 BASE64Decoder()一直報錯，請新增Base64.jar；

附：ResCoder

public class RSACoder {
    private static final String KEY_ALGORITHM = "RSA";
    private static final String CIPHER_TYPE = "RSA/None/PKCS1Padding"; // Android端加密演算法
    private static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    private static final String PUBLIC_KEY = "RSAPublicKey";
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;

    /**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;

    public static byte[] decryptBASE64(String key) {
        return Base64.decode(key, Base64.NO_WRAP);
//        return Base64.getDecoder().decode(key);
    }

    public static String encryptBASE64(byte[] bytes) {
        return Base64.encodeToString(bytes, Base64.NO_WRAP);
//        return Base64.getEncoder().encodeToString(bytes);
    }

    /**
     * 用私鑰對資訊生成數字簽名
     *
     * @param data       加密資料
     * @param privateKey 私鑰
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64編碼的私鑰
        byte[] keyBytes = decryptBASE64(privateKey);
        // 構造PKCS8EncodedKeySpec物件
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密演算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取私鑰匙物件
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 用私鑰對資訊生成數字簽名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(priKey);
        signature.update(data);
        return encryptBASE64(signature.sign());
    }

    /**
     * 校驗數字簽名
     *
     * @param data      加密資料
     * @param publicKey 公鑰
     * @param sign      數字簽名
     * @return 校驗成功返回true 失敗返回false
     * @throws Exception
     */
    public static boolean verify(byte[] data, String publicKey, String sign) throws Exception {
        // 解密由base64編碼的公鑰
        byte[] keyBytes = decryptBASE64(publicKey);
        // 構造X509EncodedKeySpec物件
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密演算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取公鑰匙物件
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pubKey);
        signature.update(data);
        // 驗證簽名是否正常
        return signature.verify(decryptBASE64(sign));
    }

    /**
     * 私鑰解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] data, String key) throws Exception {
        // 對金鑰解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得私鑰
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 對資料解密
        Cipher cipher = Cipher.getInstance(CIPHER_TYPE);
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對資料分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /**
     * 解密<br>
     * 用私鑰解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(String data, String key) throws Exception {
        return decryptByPrivateKey(decryptBASE64(data), key);
    }

    /**
     * 解密<br>
     * 用公鑰解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data, String key) throws Exception {
        // 對金鑰解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得公鑰
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 對資料解密
        Cipher cipher = Cipher.getInstance(CIPHER_TYPE);
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對資料分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }

    /**
     * 加密<br>
     * 用公鑰加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(String data, String key) throws Exception {
        // 對公鑰解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得公鑰
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 對資料加密(分段)
        Cipher cipher = Cipher.getInstance(CIPHER_TYPE);
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] dataByteArray = data.getBytes();
        int inputLen = dataByteArray.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對資料分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(dataByteArray, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(dataByteArray, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * 加密<br>
     * 用私鑰加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String key) throws Exception {
        // 對金鑰解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得私鑰
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 對資料加密
        Cipher cipher = Cipher.getInstance(CIPHER_TYPE);
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 對資料分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }

    /**
     * 取得私鑰
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Key> keyMap) {
        Key key = keyMap.get(PRIVATE_KEY);
        return encryptBASE64(key.getEncoded());
    }

    /**
     * 取得公鑰
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Key> keyMap) {
        Key key = keyMap.get(PUBLIC_KEY);
        return encryptBASE64(key.getEncoded());
    }

    /**
     * 初始化金鑰
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Key> initKey() throws NoSuchAlgorithmException {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        Map<String, Key> keyMap = new HashMap<>(2);
        keyMap.put(PUBLIC_KEY, keyPair.getPublic());// 公鑰
        keyMap.put(PRIVATE_KEY, keyPair.getPrivate());// 私鑰
        return keyMap;
    }
}