使用openSSL 生成公私鑰可以參考作者 JackCousins 的文章 @http://blog.csdn.net/chaijunkun/article/details/7275632 寫的非常好，鼓掌
但在使用的過程中發現 ，例如 我在手機中可以使用公鑰簽名，伺服器daunting使用私鑰解密，在這個過程中需要傳遞資料，那麼就是string型別的，故我們可以稍微改一下 程式碼如下  ，做個筆記標記一下

    private PrivateKey getPrivateKey() throws Exception {
        InputStream fis = new FileInputStream(new File("pkcs8_rsa_private_key.pem"));
        BufferedReader br = new BufferedReader(new InputStreamReader(fis));
        String key = br.readLine();
        br.close();
        fis.close();
        BASE64Decoder base64Decoder = new BASE64Decoder();
        byte[] buffer = base64Decoder.decodeBuffer(key);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePrivate(keySpec);

    }

    private PublicKey getPublicKey() throws Exception {
        InputStream fis = new FileInputStream(new File("rsa_public_key.pem"));
        BufferedReader br = new BufferedReader(new InputStreamReader(fis));
        String key = br.readLine();
        br.close();
        fis.close();
        BASE64Decoder base64Decoder = new BASE64Decoder();
        byte[] buffer = base64Decoder.decodeBuffer(key);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
        return keyFactory.generatePublic(keySpec);
    }

    private String encryptByPublicKey(PublicKey publicKey, byte[] data) throws Exception {
        //        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        BASE64Encoder base64Encoder = new BASE64Encoder();
        return base64Encoder.encode(cipher.doFinal(data, 0, data.length));
    }

    public String decrypt(String cipherData) throws Exception {
        Cipher cipher = null;
        cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, getPrivateKey());
        BASE64Decoder base64Decoder = new BASE64Decoder();
        byte[] output = cipher.doFinal(base64Decoder.decodeBuffer(cipherData));
        return new String(output);

    }

    public String encode(String text) {
        byte[] data = text.getBytes();
        String value = null;
        try {
            value = new String(encryptByPublicKey(getPublicKey(), data));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return value;
    }

    public static void main(String[] args) throws Exception {
        HttpRSAUtil httpRSAUtil = new HttpRSAUtil();
        String encoder = httpRSAUtil.encryptByPublicKey(httpRSAUtil.getPublicKey(),
                "123456".getBytes());
        System.out.println(encoder);
        System.err.println(httpRSAUtil.decrypt(encoder));
        //        encryptByPublicKey
    }