Java Google 验证码

Google 验证码类似短信,每隔30s 更换一次,最重要的是免费!

它解决了什么问题?

  • 登陆暴力破解
  • 安全认证

其实就重要是因为它30s更换一次验证码,可防止DDOS,暴力破解!

用于服务端的验证码!

google authenticator 手机客户端

手机端安装

  • Android移动设备

    在您手机的应用市场搜索“Google身份验证器”或“Google Authenticator”,
    然后下载安装即可。
    
    拥有Google身份验证器的市场有:
    
    1. Google Play;
    2. 应用汇;
    3. 安卓市场;
    4. 百度移动应用;
    
  • iOS移动设备

    进入应用市场,搜索“Google Authenticator”,下载安装即可。

代码示例

  • GoogleAuthenticator
/**
 * Java Server side class for Google Authenticator's TOTP generator
 * Thanks to Enrico's blog for the sample code:
 * @see http://thegreyblog.blogspot.com/2011/12/google-authenticator-using-it-in-your.html
 * @see http://code.google.com/p/google-authenticator
 * @see http://tools.ietf.org/id/draft-mraihi-totp-timebased-06.txt
 */
public class GoogleAuthenticator {

    // taken from Google pam docs - we probably don't need to mess with these
    public static final int SECRET_SIZE = 10;

    public static final String SEED = "g8GjEvTbW5oVSV7avLBdwIHqGlUYNzKFI7izOF8GwLDVKs2m0QN7vxRs2im5MDaNCWGmcD2rvcZx";

    public static final String RANDOM_NUMBER_ALGORITHM = "SHA1PRNG";

    int window_size = 3; // default 3 - max 17 (from google docs)最多可偏移的时间

    /**
     * set the windows size. This is an integer value representing the number of 30 second windows
     * we allow
     * The bigger the window, the more tolerant of clock skew we are.
     * @param s window size - must be >=1 and <=17. Other values are ignored
     */
    public void setWindowSize(int s) {
        if (s >= 1 && s <= 17)
            window_size = s;
    }

    /**
     * Generate a random secret key. This must be saved by the server and associated with the
     * users account to verify the code displayed by Google Authenticator.
     * The user must register this secret on their device.
     * @return secret key
     */
    public static String generateSecretKey() {
        SecureRandom sr = null;
        try {
            sr = SecureRandom.getInstance(RANDOM_NUMBER_ALGORITHM);
            sr.setSeed(Base64.decodeBase64(SEED));
            byte[] buffer = sr.generateSeed(SECRET_SIZE);
            Base32 codec = new Base32();
            byte[] bEncodedKey = codec.encode(buffer);
            String encodedKey = new String(bEncodedKey);
            return encodedKey;
        }catch (NoSuchAlgorithmException e) {
            // should never occur... configuration error
        }
        return null;
    }

    /**
     * Return a URL that generates and displays a QR barcode. The user scans this bar code with the
     * Google Authenticator application on their smartphone to register the auth code. They can also
     * manually enter the
     * secret if desired
     * @param user user id (e.g. fflinstone)
     * @param host host or system that the code is for (e.g. myapp.com)
     * @param secret the secret that was previously generated for this user
     * @return the URL for the QR code to scan
     */
    public static String getQRBarcodeURL(String user, String host, String secret) {
        String format = "https://www.google.com/chart?chs=200x200&chld=M%%7C0&cht=qr&chl=otpauth://totp/%s@%s%%3Fsecret%%3D%s";
        return String.format(format, user, host, secret);
    }

    /**
     * Check the code entered by the user to see if it is valid
     * @param secret The users secret.
     * @param code The code displayed on the users device
     * @param t The time in msec (System.currentTimeMillis() for example)
     * @return
     */
    public boolean check_code(String secret, long code, long timeMsec) {
        Base32 codec = new Base32();
        byte[] decodedKey = codec.decode(secret);
        // convert unix msec time into a 30 second "window"
        // this is per the TOTP spec (see the RFC for details)
        long t = (timeMsec / 1000L) / 30L;
        // Window is used to check codes generated in the near past.
        // You can use this value to tune how far you're willing to go.
        for (int i = -window_size; i <= window_size; ++i) {
            long hash;
            try {
                hash = verify_code(decodedKey, t + i);
            }catch (Exception e) {
                // Yes, this is bad form - but
                // the exceptions thrown would be rare and a static configuration problem
                e.printStackTrace();
                throw new RuntimeException(e.getMessage());
                //return false;
            }
            if (hash == code) {
                return true;
            }
        }
        // The validation code is invalid.
        return false;
    }

    private static int verify_code(byte[] key, long t) throws NoSuchAlgorithmException, InvalidKeyException {
        byte[] data = new byte[8];
        long value = t;
        for (int i = 8; i-- > 0; value >>>= 8) {
            data[i] = (byte) value;
        }
        SecretKeySpec signKey = new SecretKeySpec(key, "HmacSHA1");
        Mac mac = Mac.getInstance("HmacSHA1");
        mac.init(signKey);
        byte[] hash = mac.doFinal(data);
        int offset = hash[20 - 1] & 0xF;
        // We're using a long because Java hasn't got unsigned int.
        long truncatedHash = 0;
        for (int i = 0; i < 4; ++i) {
            truncatedHash <<= 8;
            // We are dealing with signed bytes:
            // we just keep the first byte.
            truncatedHash |= (hash[offset + i] & 0xFF);
        }
        truncatedHash &= 0x7FFFFFFF;
        truncatedHash %= 1000000;
        return (int) truncatedHash;
    }
}
  • GoogleUtil
public class GoogleUtil {

    public  static boolean checkGoogleCode(String googleKey, String googleCode){
        long t = System.currentTimeMillis();
        GoogleAuthenticator ga = new GoogleAuthenticator();
        ga.setWindowSize(5); //should give 5 * 30 seconds of grace...
        return ga.check_code(googleKey, Long.parseLong(googleCode), t);
    }
}
  • GoogleAuthTest
public class GoogleAuthTest {

    public static void main(String[] args) {
        genSecretTest();
//        authTest();
        }
    public static void genSecretTest() {
        String secret = GoogleAuthenticator.generateSecretKey();
        String url = GoogleAuthenticator.getQRBarcodeURL("admin", "dev", secret);
        System.out.println("Please register " + url);
        System.out.println("Secret key is " + secret);
    }

    // Change this to the saved secret from the running the above test.
    static String savedSecret = "BSZLN576KZD2ZKJA";

    public static void authTest() {
        // enter the code shown on device. Edit this and run it fast before the code expires!
        long code = 432939;
        long t = System.currentTimeMillis();
        GoogleAuthenticator ga = new GoogleAuthenticator();
        ga.setWindowSize(2); //should give 5 * 30 seconds of grace...
        boolean r = ga.check_code(savedSecret, code, t);
        System.out.println("Check code = " + r);
    }
}