Android使用RSA加密和解密的示例代码

  /**RSA算法*/
  public static final String RSA = "RSA";
  /**加密方式，android的*/
// public static final String TRANSFORMATION = "RSA/None/NoPadding";
  /**加密方式，标准jdk的*/
  public static final String TRANSFORMATION = "RSA/None/PKCS1Padding";

  /** 使用公钥加密 */
  public static byte[] encryptByPublicKey(byte[] data, byte[] publicKey) throws Exception {
    // 得到公钥对象
    X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKey);
    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    PublicKey pubKey = keyFactory.generatePublic(keySpec);
    // 加密数据
    Cipher cp = Cipher.getInstance(TRANSFORMATION);
    cp.init(Cipher.ENCRYPT_MODE, pubKey);
    return cp.doFinal(data);
  }

  /** 使用私钥解密 */
  public static byte[] decryptByPrivateKey(byte[] encrypted, byte[] privateKey) throws Exception {
    // 得到私钥对象
    PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKey);
    KeyFactory kf = KeyFactory.getInstance(RSA);
    PrivateKey keyPrivate = kf.generatePrivate(keySpec);
    // 解密数据
    Cipher cp = Cipher.getInstance(TRANSFORMATION);
    cp.init(Cipher.DECRYPT_MODE, keyPrivate);
    byte[] arr = cp.doFinal(encrypted);
    return arr;
  }

  String data = "hello world";
  try {
    int keyLength = 1024;
    //生成密钥对
    KeyPair keyPair = RSAUtils.generateRSAKeyPair(keyLength);
    //获取公钥
    byte[] publicKey = RSAUtils.getPublicKey(keyPair);
    //获取私钥
    byte[] privateKey = RSAUtils.getPrivateKey(keyPair);
    
    //用公钥加密
    byte[] encrypt = RSAUtils.encryptByPublicKey(data.getBytes(), publicKey);
    Log.d("TAG", "加密后的数据：" + StringUtils.byteArrayToString(encrypt));
    
    //用私钥解密
    byte[] decrypt = RSAUtils.decryptByPrivateKey(encrypt, privateKey);
    Log.d("TAG", "解密后的数据：" + new String(decrypt, "utf-8"));
  } catch (Exception e) {
    e.printStackTrace();
  }

    String data = "hello world";
    //读取公钥文件
    String publicKeyString = IOUtils.readAssetsFile(this, "rsa_public_key.pem");
    //base64解码
    byte[] publicKey = Base64Utils.decodeToBytes(publicKeyString);
    
    try {
      //加密
      byte[] encrypt = RSAUtils.encryptByPublicKey(data.getBytes(), publicKey);
      Log.d("TAG", "加密后的数据：" + StringUtils.byteArrayToString(encrypt));
      
//     //读取私钥文件
//     String privateKeyString = IOUtils.readAssetsFile(this, "rsa_private_key.pem");
//     //base64解码
//     byte[] privateKey = Base64Utils.decodeToBytes(privateKeyString);
//     //解密
//     byte[] decrypt = RSAUtils.decryptByPrivateKey(encrypt, privateKey);
//     Log.d("TAG", "解密后的数据：" + new String(decrypt, "utf-8"));
    } catch (Exception e) {
      e.printStackTrace();
    }

  /**秘钥默认长度*/
  public static final int DEFAULT_KEY_SIZE = 1024;
  /**加密的数据最大的字节数，即117个字节*/
  public static final int DEFAULT_BUFFERSIZE = (DEFAULT_KEY_SIZE / 8) - 11;
  /**当加密的数据超过DEFAULT_BUFFERSIZE，则使用分段加密*/
  public static final byte[] DEFAULT_SPLIT = "#PART#".getBytes();

  /** 使用公钥分段加密 */
  public static byte[] encryptByPublicKeyForSpilt(byte[] data, byte[] publicKey) throws Exception{
    int dataLen = data.length;
    if (dataLen <= DEFAULT_BUFFERSIZE) {
      return encryptByPublicKey(data, publicKey);
    }
    List allBytes = new ArrayList(2048);
    int bufIndex = 0;
    int subDataLoop = 0;
    byte[] buf = new byte[DEFAULT_BUFFERSIZE];
    for (int i = 0; i  allBytes = new ArrayList(1024);
    int latestStartIndex = 0;
    for (int i = 0; i  1) {
          if (i + splitLen 

    String data = "hello world hello world hello world hello world hello world hello world hello world hello world " +
        "hello world hello world hello world hello world hello world hello world hello world hello world hello world " +
        "hello world hello world hello world hello world hello world hello world hello world hello world hello world ";
    Log.d("TAG", "要加密的数据：" + data + ", 要加密的数据长度：" + data.length());
    try {
      //分段加密
      byte[] encrypt = RSAUtils.encryptByPublicKeyForSpilt(data.getBytes(), publicKey);
      Log.d("TAG", "加密后的数据：" + StringUtils.byteArrayToString(encrypt));
      
      //分段解密
      byte[] decrypt = RSAUtils.decryptByPrivateKeyForSpilt(encrypt, privateKey);
      Log.d("TAG", "解密后的数据：" + new String(decrypt, "utf-8"));
    } catch (Exception e) {
      e.printStackTrace();
    }

  /** 生成密钥对，即公钥和私钥。key长度是512-2048，一般为1024 */
  public static KeyPair generateRSAKeyPair(int keyLength) throws NoSuchAlgorithmException {
    KeyPairGenerator kpg = KeyPairGenerator.getInstance(RSA);
    kpg.initialize(keyLength);
    return kpg.genKeyPair();
  }

  /** 获取公钥，打印为48-12613448136942-12272-122-913111503-126115048-12...等等一长串用-拼接的数字 */
  public static byte[] getPublicKey(KeyPair keyPair) {
    RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
    return rsaPublicKey.getEncoded();
  }

  /** 获取私钥，同上 */
  public static byte[] getPrivateKey(KeyPair keyPair) {
    RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
    return rsaPrivateKey.getEncoded();
  }

    int keyLength = 1024;
    try {
      //生成密钥对
      KeyPair keyPair = RSAUtils.generateRSAKeyPair(keyLength);

      //获取公钥
      byte[] publicKey = RSAUtils.getPublicKey(keyPair);
      Log.d("TAG", "公钥：" + StringUtils.byteArrayToString(publicKey));
      //公钥用base64编码
      String encodePublic = Base64Utils.encodeToString(publicKey);
      Log.d("TAG", "base64编码的公钥：" + encodePublic);

      //获取私钥
      byte[] privateKey = RSAUtils.getPrivateKey(keyPair);
      Log.d("TAG", "私钥：" + StringUtils.byteArrayToString(privateKey));
      //私钥用base64编码
      String encodePrivate = Base64Utils.encodeToString(privateKey);
      Log.d("TAG", "base64编码的私钥：" + encodePrivate);
    } catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
    }