鏈接:https://www.zhihu.com/question/20462696/answer/18731073
來源:知乎
著作權歸作者所有。商業轉載請聯繫作者獲得授權,非商業轉載請註明出處。
實現Google Authenticator功能需要服務器端和客戶端的支持。服務器端負責密鑰的生成、驗證一次性密碼是否正確。客戶端記錄密鑰後生成一次性密碼。
目前客戶端有:
android版: Google 身份驗證器
iOS版:https://itunes.apple.com/cn/app/google-authenticator/id388497605
實現原理:
一、用戶需要開啓Google Authenticator服務時,
1.服務器隨機生成一個類似於『DPI45HKISEXU6HG7』的密鑰,並且把這個密鑰保存在數據庫中。
2.在頁面上顯示一個二維碼,內容是一個URI地址(otpauth://totp/賬號?secret=密鑰),如『otpauth://totp/[email protected]?secret=DPI45HCEBCJK6HG7』,下圖:
otpauth://totp/[email protected]?secret=DPI45HCEBCJK6HG7 (二維碼自動識別)
3.客戶端掃描二維碼,把密鑰『DPI45HKISEXU6HG7』保存在客戶端。
二、用戶需要登陸時
1.客戶端每30秒使用密鑰『DPI45HKISEXU6HG7』和時間戳通過一種『算法』生成一個6位數字的一次性密碼,如『684060』。如下圖android版界面:
<img src="https://pic1.zhimg.com/c2056261a0b106af19517697887c0b38_b.jpg" data-rawwidth="281" data-rawheight="398" class="content_image" width="281">
2.用戶登陸時輸入一次性密碼『684060』。
3.服務器端使用保存在數據庫中的密鑰『DPI45HKISEXU6HG7』和時間戳通過同一種『算法』生成一個6位數字的一次性密碼。大家都懂控制變量法,如果算法相同、密鑰相同,又是同一個時間(時間戳相同),那麼客戶端和服務器計算出的一次性密碼是一樣的。服務器驗證時如果一樣,就登錄成功了。
Tips:
1.這種『算法』是公開的,所以服務器端也有很多開源的實現,比如php版的:https://github.com/PHPGangsta/GoogleAuthenticator 。上github搜索『Google Authenticator』可以找到更多語言版的Google Authenticator。
2.所以,你在自己的項目可以輕鬆加入對Google Authenticator的支持,在一個客戶端上顯示多個賬戶的效果可以看上面android版界面的截圖。目前dropbox、lastpass、wordpress,甚至vps等第三方應用都支持Google Authenticator登陸,請自行搜索。
3.現實生活中,網銀、網絡遊戲的實體動態口令牌其實原理也差不多,大家可以自行腦補下,謝謝。
著作權歸作者所有。商業轉載請聯繫作者獲得授權,非商業轉載請註明出處。
- //Google Authenticator
- // 只從google出了雙重身份驗證後,就方便了大家,等同於有了google一個級別的安全,但是我們該怎麼使用google authenticator (雙重身份驗證),
- //下面是java的算法,這樣大家都可以得到根據key得到公共的祕鑰了,直接複製,記得導入JAR包:
- //
- //commons-codec-1.8.jar
- //
- //junit-4.10.jar
- //測試方法:
- //
- //1、執行測試代碼中的“genSecret”方法,將生成一個KEY(用戶爲testuser),URL打開是一張二維碼圖片。
- //
- //2、在手機中下載“GOOGLE身份驗證器”。
- //
- //3、在身份驗證器中配置賬戶,輸入賬戶名(第一步中的用戶testuser)、密鑰(第一步生成的KEY),選擇基於時間。
- //
- //4、運行authcode方法將key和要測試的驗證碼帶進去(codes,key),就可以知道是不是正確的祕鑰了!返回值布爾
- //main我就不寫了大家~~因爲這個可以當做util工具直接調用就行了
- //
- package coin.util;
- 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;
- 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)最多可偏移的時間
- public void setWindowSize(int s) {
- if (s >= 1 && s <= 17)
- window_size = s;
- }
- public static Boolean authcode(String codes, String savedSecret) {
- // enter the code shown on device. Edit this and run it fast before the
- // code expires!
- long code = Long.parseLong(codes);
- long t = System.currentTimeMillis();
- GoogleAuthenticator ga = new GoogleAuthenticator();
- ga.setWindowSize(15); // should give 5 * 30 seconds of grace...
- boolean r = ga.check_code(savedSecret, code, t);
- return r;
- }
- public static String genSecret() {
- String secret = GoogleAuthenticator.generateSecretKey();
- GoogleAuthenticator.getQRBarcodeURL("testuser",
- "testhost", secret);
- return secret;
- }
- 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;
- }
- 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);
- }
- 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;
- }
- }
//Google Authenticator
// 只從google出了雙重身份驗證後,就方便了大家,等同於有了google一個級別的安全,但是我們該怎麼使用google authenticator (雙重身份驗證),
//下面是java的算法,這樣大家都可以得到根據key得到公共的祕鑰了,直接複製,記得導入JAR包:
//
//commons-codec-1.8.jar
//
//junit-4.10.jar
//測試方法:
//
//1、執行測試代碼中的“genSecret”方法,將生成一個KEY(用戶爲testuser),URL打開是一張二維碼圖片。
//
//2、在手機中下載“GOOGLE身份驗證器”。
//
//3、在身份驗證器中配置賬戶,輸入賬戶名(第一步中的用戶testuser)、密鑰(第一步生成的KEY),選擇基於時間。
//
//4、運行authcode方法將key和要測試的驗證碼帶進去(codes,key),就可以知道是不是正確的祕鑰了!返回值布爾
//main我就不寫了大家~~因爲這個可以當做util工具直接調用就行了
//
package coin.util;
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;
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)最多可偏移的時間
public void setWindowSize(int s) {
if (s >= 1 && s <= 17)
window_size = s;
}
public static Boolean authcode(String codes, String savedSecret) {
// enter the code shown on device. Edit this and run it fast before the
// code expires!
long code = Long.parseLong(codes);
long t = System.currentTimeMillis();
GoogleAuthenticator ga = new GoogleAuthenticator();
ga.setWindowSize(15); // should give 5 * 30 seconds of grace...
boolean r = ga.check_code(savedSecret, code, t);
return r;
}
public static String genSecret() {
String secret = GoogleAuthenticator.generateSecretKey();
GoogleAuthenticator.getQRBarcodeURL("testuser",
"testhost", secret);
return secret;
}
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;
}
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);
}
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;
}
}