Class RSAUtil

android/RSAUtil.java:22–131

Android 这里和java 是不完全一样的

 * Android 这里和java 是不完全一样的
 */
public class RSAUtil {
    /**
     * RSA最大加密明文大小
     */
    private final static int MAX_ENCRYPT_BLOCK = 117;

    private final static String thpubk = "5JLdcTOCLc2r9Y6jRI1/MnJfjhNQ6I4dwblHyzaEquxM8qo5QvYydDE+wIDAQAB";
    /**
     * RSA最大加密明文大小
     */
    private final static String thprik = "lalalalalla";
    /**
     * RSA最大解密密文大小
     */
    private final static int MAX_DECRYPT_BLOCK = 128;

    /**
     * 获取公钥
     *
     * @param publicKey 公钥字符串
     * @return
     */
    public static PublicKey getPublicKey(String publicKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decode(publicKey.getBytes(), Base64.NO_WRAP);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decodedKey);
        return keyFactory.generatePublic(keySpec);
    }
    /**
     * 获取私钥
     *
     * @param privateKey 私钥字符串
     * @return
     */
    public static PrivateKey getPrivateKey(String privateKey) throws Exception {
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        byte[] decodedKey = Base64.decode(privateKey.getBytes(),Base64.NO_WRAP);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
        return keyFactory.generatePrivate(keySpec);
    }


    /**
     * RSA加密
     *
     * @param data 待加密数据
     * @return
     */
    public static String encrypt(String data) throws InvalidKeySpecException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException, IOException {
        PublicKey publicKey = getPublicKey(thpubk);
        Cipher cipher = Cipher.getInstance("RSA/None/PKCS1Padding");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        int inputLen = data.getBytes().length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offset = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密