代码来源：https://github.com/wstrange/GoogleAuth
验证代码：
package com.warner.java;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.codec.binary.Base32;
import org.apache.commons.codec.binary.Base64;
/**
* 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;
}
}测试代码：
package com.warner.test;
import org.junit.Test;
import com.warner.java.GoogleAuthenticator;
/*
* Not really a unit test- but it shows usage
*/
public class GoogleAuthTest {
@Test
public void genSecretTest() {
String secret = GoogleAuthenticator.generateSecretKey();
String url = GoogleAuthenticator.getQRBarcodeURL("testuser", "testhost", 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 = "F6EUJJMYK7GDC4KI";
@Test
public void authTest() {
// enter the code shown on device. Edit this and run it fast before the code expires!
long code = 349394;
long t = System.currentTimeMillis();
GoogleAuthenticator ga = new GoogleAuthenticator();
ga.setWindowSize(5); //should give 5 * 30 seconds of grace...
boolean r = ga.check_code(savedSecret, code, t);
System.out.println("Check code = " + r);
}
}
所需JAR包：
commons-codec-1.8.jar
junit-4.10.jar
测试方法：
1、执行测试代码中的“genSecretTest”方法，将生成一个URL和一个KEY（用户为testuser），URL打开是一张二维码图片。
2、在手机中下载“GOOGLE身份验证器”。
3、在身份验证器中配置账户，输入账户名（第一步中的用户testuser）、密钥（第一步生成的KEY），选择基于时间。
4、修改测试代码中的“savedSecret”属性，用身份验证器中显示的数字替换测试代码中方法authTest中的code，运行authTest方法即可。