為 Android 應用程式新增多重驗證機制

本文說明如何在 Android 應用程式中新增簡訊多重驗證機制。

多重驗證可以提升應用程式的安全性。攻擊者通常會竊取密碼及盜用社群媒體帳戶，但攔截簡訊的難度較高。

事前準備

  1. 至少啟用一個支援多重驗證的供應商。除了電話驗證、匿名驗證和 Apple Game Center 以外，所有供應商都支援 MFA。

  2. 請確認您的應用程式會驗證使用者的電子郵件地址。多重驗證需要通過電子郵件驗證。這麼做可防止惡意人士使用不屬於自己的電子郵件地址註冊服務，然後透過新增第二個因素將真正的擁有者鎖在門外。

  3. 在 Firebase 主控台註冊應用程式的 SHA-1 雜湊 (變更內容會自動轉移至 Google Cloud Identity Platform)。

    1. 請按照「驗證用戶端」一文中的步驟，取得應用程式的 SHA-1 雜湊值。

    2. 開啟 Firebase 控制台。

    3. 前往「專案設定」。

    4. 在「你的應用程式」下方，按一下 Android 圖示。

    5. 按照指示步驟新增 SHA-1 雜湊。

啟用多重驗證

  1. 前往 Google Cloud 控制台的「Identity Platform MFA」頁面。
    前往多重驗證

  2. 在「多重驗證」中，按一下「啟用」。

  3. 輸入您要用來測試應用程式的電話號碼。雖然這不是必要步驟，我們仍強烈建議您註冊測試電話號碼，以免在開發期間發生節流情形。

  4. 如果您尚未授權應用程式的網域，請按一下「新增網域」，將網域加入許可清單。

  5. 按一下 [儲存]。

選擇註冊模式

您可以選擇應用程式是否需要多重驗證，以及註冊使用者的方式和時間。常見的模式包括：

  • 在註冊過程中註冊使用者的第二重驗證。如果您的應用程式要求所有使用者都必須進行多重驗證，請使用這個方法。

  • 提供可略過的選項，讓使用者在註冊時註冊第二重驗證。如要鼓勵使用者採用多重驗證，但不強制要求使用者採用，則可能會偏好這種做法。

  • 提供從使用者帳戶或個人資料管理頁面新增第二因素的功能，而非在註冊畫面中提供。這樣一來，註冊程序的摩擦力會降到最低，同時仍可讓重視安全性的使用者使用多重驗證。

  • 當使用者想要存取需要更高安全性要求的功能時，要求逐步新增第二個因素。

註冊次要驗證方式

如要為使用者註冊新的次要驗證方法，請按照下列步驟操作：

  1. 重新驗證使用者。

  2. 請使用者輸入電話號碼。

  3. 為使用者取得多重驗證工作階段：

    Kotlin+KTX 

    user.multiFactor.session.addOnCompleteListener { task ->
    if (task.isSuccessful) {
        val multiFactorSession: MultiFactorSession? = task.result
    }
}

    Java

    user.getMultiFactor().getSession()
  .addOnCompleteListener(
      new OnCompleteListener<MultiFactorSession>() {
      @Override
      public void onComplete(@NonNull Task<MultiFactorSession> task) {
        if (task.isSuccessful()) {
          MultiFactorSession multiFactorSession = task.getResult();
        }
      }
      });

  4. 建構 OnVerificationStateChangedCallbacks 物件，以便在驗證程序中處理不同的事件：

    Kotlin+KTX 

    val callbacks = object : OnVerificationStateChangedCallbacks() {
    override fun onVerificationCompleted(credential: PhoneAuthCredential) {
        // This callback will be invoked in two situations:
        // 1) Instant verification. In some cases, the phone number can be
        //    instantly verified without needing to send or enter a verification
        //    code. You can disable this feature by calling
        //    PhoneAuthOptions.builder#requireSmsValidation(true) when building
        //    the options to pass to PhoneAuthProvider#verifyPhoneNumber().
        // 2) Auto-retrieval. On some devices, Google Play services can
        //    automatically detect the incoming verification SMS and perform
        //    verification without user action.
        this@MainActivity.credential = credential
    }

    override fun onVerificationFailed(e: FirebaseException) {
        // This callback is invoked in response to invalid requests for
        // verification, like an incorrect phone number.
        if (e is FirebaseAuthInvalidCredentialsException) {
            // Invalid request
            // ...
        } else if (e is FirebaseTooManyRequestsException) {
            // The SMS quota for the project has been exceeded
            // ...
        }
        // Show a message and update the UI
        // ...
    }

    override fun onCodeSent(
        verificationId: String, forceResendingToken: ForceResendingToken
    ) {
        // The SMS verification code has been sent to the provided phone number.
        // We now need to ask the user to enter the code and then construct a
        // credential by combining the code with a verification ID.
        // Save the verification ID and resending token for later use.
        this@MainActivity.verificationId = verificationId
        this@MainActivity.forceResendingToken = forceResendingToken
        // ...
    }
}

    Java

    OnVerificationStateChangedCallbacks callbacks =
new OnVerificationStateChangedCallbacks() {
  @Override
  public void onVerificationCompleted(PhoneAuthCredential credential) {
    // This callback will be invoked in two situations:
    // 1) Instant verification. In some cases, the phone number can be
    //    instantly verified without needing to send or enter a verification
    //    code. You can disable this feature by calling
    //    PhoneAuthOptions.builder#requireSmsValidation(true) when building
    //    the options to pass to PhoneAuthProvider#verifyPhoneNumber().
    // 2) Auto-retrieval. On some devices, Google Play services can
    //    automatically detect the incoming verification SMS and perform
    //    verification without user action.
    this.credential = credential;
  }
  @Override
  public void onVerificationFailed(FirebaseException e) {
    // This callback is invoked in response to invalid requests for
    // verification, like an incorrect phone number.
    if (e instanceof FirebaseAuthInvalidCredentialsException) {
    // Invalid request
    // ...
    } else if (e instanceof FirebaseTooManyRequestsException) {
    // The SMS quota for the project has been exceeded
    // ...
    }
    // Show a message and update the UI
    // ...
  }
  @Override
  public void onCodeSent(
    String verificationId, PhoneAuthProvider.ForceResendingToken token) {
    // The SMS verification code has been sent to the provided phone number.
    // We now need to ask the user to enter the code and then construct a
    // credential by combining the code with a verification ID.
    // Save the verification ID and resending token for later use.
    this.verificationId = verificationId;
    this.forceResendingToken = token;
    // ...
  }
};

  5. 使用使用者的電話號碼、多重驗證工作階段和回呼，初始化 PhoneInfoOptions 物件：

    Kotlin+KTX 

    val phoneAuthOptions = PhoneAuthOptions.newBuilder()
    .setPhoneNumber(phoneNumber)
    .setTimeout(30L, TimeUnit.SECONDS)
    .setMultiFactorSession(MultiFactorSession)
    .setCallbacks(callbacks)
    .build()

    Java

    PhoneAuthOptions phoneAuthOptions =
  PhoneAuthOptions.newBuilder()
      .setPhoneNumber(phoneNumber)
      .setTimeout(30L, TimeUnit.SECONDS)
      .setMultiFactorSession(multiFactorSession)
      .setCallbacks(callbacks)
      .build();

    根據預設，系統會啟用即時驗證功能。如要停用，請新增對 requireSmsValidation(true) 的呼叫。

  6. 將驗證訊息傳送至使用者的手機：

    Kotlin+KTX 

    PhoneAuthProvider.verifyPhoneNumber(phoneAuthOptions)

    Java

    PhoneAuthProvider.verifyPhoneNumber(phoneAuthOptions);

    雖然這不是強制規定，但建議您事先告知使用者，他們將收到簡訊，並且會收取標準費率。

  7. 傳送簡訊碼後，請要求使用者驗證這組碼：

    Kotlin+KTX 

    // Ask user for the verification code.
val credential = PhoneAuthProvider.getCredential(verificationId, verificationCode)

    Java

    // Ask user for the verification code.
PhoneAuthCredential credential
  = PhoneAuthProvider.getCredential(verificationId, verificationCode);

  8. 使用 PhoneAuthCredential 初始化 MultiFactorAssertion 物件：

    Kotlin+KTX 

    val multiFactorAssertion
  = PhoneMultiFactorGenerator.getAssertion(credential)

    Java

    MultiFactorAssertion multiFactorAssertion
  = PhoneMultiFactorGenerator.getAssertion(credential);

  9. 完成註冊。您可以選擇為第二個因素指定顯示名稱。這對擁有多個次要驗證方法的使用者來說很有幫助，因為電話號碼會在驗證流程中遮蓋 (例如 +1******1234)。

    Kotlin+KTX 

    // Complete enrollment. This will update the underlying tokens
// and trigger ID token change listener.
FirebaseAuth.getInstance()
    .currentUser
    ?.multiFactor
    ?.enroll(multiFactorAssertion, "My personal phone number")
    ?.addOnCompleteListener {
        // ...
    }

    Java

    // Complete enrollment. This will update the underlying tokens
// and trigger ID token change listener.
FirebaseAuth.getInstance()
  .getCurrentUser()
  .getMultiFactor()
  .enroll(multiFactorAssertion, "My personal phone number")
  .addOnCompleteListener(
      new OnCompleteListener<Void>() {
      @Override
      public void onComplete(@NonNull Task<Void> task) {
        // ...
      }
      });

以下程式碼為註冊第二個因素的完整範例：

Kotlin+KTX 

val multiFactorAssertion = PhoneMultiFactorGenerator.getAssertion(credential)
user.multiFactor.session
    .addOnCompleteListener { task ->
        if (task.isSuccessful) {
            val multiFactorSession = task.result
            val phoneAuthOptions = PhoneAuthOptions.newBuilder()
                .setPhoneNumber(phoneNumber)
                .setTimeout(30L, TimeUnit.SECONDS)
                .setMultiFactorSession(multiFactorSession)
                .setCallbacks(callbacks)
                .build()
            // Send SMS verification code.
            PhoneAuthProvider.verifyPhoneNumber(phoneAuthOptions)
        }
    }

// Ask user for the verification code.
val credential = PhoneAuthProvider.getCredential(verificationId, verificationCode)

val multiFactorAssertion = PhoneMultiFactorGenerator.getAssertion(credential)

// Complete enrollment.
FirebaseAuth.getInstance()
    .currentUser
    ?.multiFactor
    ?.enroll(multiFactorAssertion, "My personal phone number")
    ?.addOnCompleteListener {
        // ...
    }

Java

MultiFactorAssertion multiFactorAssertion = PhoneMultiFactorGenerator.getAssertion(credential);
user.getMultiFactor().getSession()
  .addOnCompleteListener(
      new OnCompleteListener<MultiFactorSession>() {
      @Override
      public void onComplete(@NonNull Task<MultiFactorSession> task) {
        if (task.isSuccessful()) {
          MultiFactorSession multiFactorSession = task.getResult();
          PhoneAuthOptions phoneAuthOptions =
            PhoneAuthOptions.newBuilder()
                .setPhoneNumber(phoneNumber)
                .setTimeout(30L, TimeUnit.SECONDS)
                .setMultiFactorSession(multiFactorSession)
                .setCallbacks(callbacks)
                .build();
          // Send SMS verification code.
          PhoneAuthProvider.verifyPhoneNumber(phoneAuthOptions);
        }
      }
      });

// Ask user for the verification code.
PhoneAuthCredential credential =
  PhoneAuthProvider.getCredential(verificationId, verificationCode);

MultiFactorAssertion multiFactorAssertion = PhoneMultiFactorGenerator.getAssertion(credential);
// Complete enrollment.
FirebaseAuth.getInstance()
  .getCurrentUser()
  .getMultiFactor()
  .enroll(multiFactorAssertion, "My personal phone number")
  .addOnCompleteListener(
      new OnCompleteListener<Void>() {
      @Override
      public void onComplete(@NonNull Task<Void> task) {
        // ...
      }
      });

恭喜！您已為使用者成功註冊第二個驗證因素。

使用第二種驗證方法登入

如要使用簡訊雙重驗證登入使用者，請按照下列步驟操作：

  1. 請使用者以第一個因素登入，然後擷取 FirebaseAuthMultiFactorException 例外狀況。這個錯誤包含解析器，可用於取得使用者註冊的第二因素。它還包含底層工作階段，證明使用者已成功透過第一因素驗證。

    舉例來說，如果使用者的第一個因素是電子郵件和密碼：

    Kotlin+KTX 

    FirebaseAuth.getInstance()
    .signInWithEmailAndPassword(email, password)
    .addOnCompleteListener(
        OnCompleteListener { task ->
            if (task.isSuccessful) {
                // User is not enrolled with a second factor and is successfully
                // signed in.
                // ...
                return@OnCompleteListener
            }
            if (task.exception is FirebaseAuthMultiFactorException) {
                // The user is a multi-factor user. Second factor challenge is
                // required.
                val multiFactorResolver =
                    (task.exception as FirebaseAuthMultiFactorException).resolver
                // ...
            } else {
                // Handle other errors, such as wrong password.
            }
        })

    Java

    FirebaseAuth.getInstance()
  .signInWithEmailAndPassword(email, password)
  .addOnCompleteListener(
      new OnCompleteListener<AuthResult>() {
      @Override
      public void onComplete(@NonNull Task<AuthResult> task) {
        if (task.isSuccessful()) {
          // User is not enrolled with a second factor and is successfully
          // signed in.
          // ...
          return;
        }
        if (task.getException() instanceof FirebaseAuthMultiFactorException) {
          // The user is a multi-factor user. Second factor challenge is
          // required.
          MultiFactorResolver multiFactorResolver = task.getException().getResolver();
          // ...
        } else {
          // Handle other errors such as wrong password.
        }
      }
      });

    如果使用者的第一個因素是聯合驗證機構 (例如 OAuth)，請在呼叫 startActivityForSignInWithProvider() 後擷取錯誤。

  2. 如果使用者註冊了多個次要驗證因素，請詢問他們要使用哪一個：

    Kotlin+KTX 

    // Ask user which second factor to use.
// You can get the list of enrolled second factors using
//   multiFactorResolver.hints

// Check the selected factor:
if (multiFactorResolver.hints[selectedIndex].factorId
    === PhoneMultiFactorGenerator.FACTOR_ID
) {
    // User selected a phone second factor.
    val selectedHint =
        multiFactorResolver.hints[selectedIndex] as PhoneMultiFactorInfo
} else if (multiFactorResolver.hints[selectedIndex].factorId
    === TotpMultiFactorGenerator.FACTOR_ID) {
    // User selected a TOTP second factor.
} else {
    // Unsupported second factor.
}

    Java

    // Ask user which second factor to use.
// You can get the masked phone number using
// resolver.getHints().get(selectedIndex).getPhoneNumber()
// You can get the display name using
// resolver.getHints().get(selectedIndex).getDisplayName()
if ( resolver.getHints()
               .get(selectedIndex)
               .getFactorId()
               .equals( PhoneMultiFactorGenerator.FACTOR_ID ) ) {
// User selected a phone second factor.
MultiFactorInfo selectedHint =
  multiFactorResolver.getHints().get(selectedIndex);
} else if ( resolver
              .getHints()
              .get(selectedIndex)
              .getFactorId()
              .equals(TotpMultiFactorGenerator.FACTOR_ID ) ) {
  // User selected a TOTP second factor.
} else {
// Unsupported second factor.
}

  3. 使用提示和多因素工作階段初始化 PhoneAuthOptions 物件。這些值包含在附加至 FirebaseAuthMultiFactorException 的解析器中。

    Kotlin+KTX 

    val phoneAuthOptions = PhoneAuthOptions.newBuilder()
    .setMultiFactorHint(selectedHint)
    .setTimeout(30L, TimeUnit.SECONDS)
    .setMultiFactorSession(multiFactorResolver.session)
    .setCallbacks(callbacks) // Optionally disable instant verification.
    // .requireSmsValidation(true)
    .build()

    Java

    PhoneAuthOptions phoneAuthOptions =
  PhoneAuthOptions.newBuilder()
      .setMultiFactorHint(selectedHint)
      .setTimeout(30L, TimeUnit.SECONDS)
      .setMultiFactorSession(multiFactorResolver.getSession())
      .setCallbacks(callbacks)
      // Optionally disable instant verification.
      // .requireSmsValidation(true)
      .build();

  4. 將驗證訊息傳送至使用者的手機：

    Kotlin+KTX 

    // Send SMS verification code
PhoneAuthProvider.verifyPhoneNumber(phoneAuthOptions)

    Java

    // Send SMS verification code
PhoneAuthProvider.verifyPhoneNumber(phoneAuthOptions);

  5. 傳送簡訊碼後，請要求使用者驗證這組碼：

    Kotlin+KTX 

    // Ask user for the verification code. Then, pass it to getCredential:
val credential =
    PhoneAuthProvider.getCredential(verificationId, verificationCode)

    Java

    // Ask user for the verification code. Then, pass it to getCredential:
PhoneAuthCredential credential
    = PhoneAuthProvider.getCredential(verificationId, verificationCode);

  6. 使用 PhoneAuthCredential 初始化 MultiFactorAssertion 物件：

    Kotlin+KTX 

    val multiFactorAssertion = PhoneMultiFactorGenerator.getAssertion(credential)

    Java

    MultiFactorAssertion multiFactorAssertion
    = PhoneMultiFactorGenerator.getAssertion(credential);

  7. 請呼叫 resolver.resolveSignIn() 完成次要驗證。接著，您可以存取原始登入結果，其中包含標準提供者專屬資料和驗證憑證：

    Kotlin+KTX 

    multiFactorResolver
    .resolveSignIn(multiFactorAssertion)
    .addOnCompleteListener { task ->
        if (task.isSuccessful) {
            val authResult = task.result
            // AuthResult will also contain the user, additionalUserInfo,
            // and an optional credential (null for email/password)
            // associated with the first factor sign-in.

            // For example, if the user signed in with Google as a first
            // factor, authResult.getAdditionalUserInfo() will contain data
            // related to Google provider that the user signed in with;
            // authResult.getCredential() will contain the Google OAuth
            //   credential;
            // authResult.getCredential().getAccessToken() will contain the
            //   Google OAuth access token;
            // authResult.getCredential().getIdToken() contains the Google
            //   OAuth ID token.
        }
    }

    Java

    multiFactorResolver
  .resolveSignIn(multiFactorAssertion)
  .addOnCompleteListener(
      new OnCompleteListener<AuthResult>() {
      @Override
      public void onComplete(@NonNull Task<AuthResult> task) {
        if (task.isSuccessful()) {
          AuthResult authResult = task.getResult();
          // AuthResult will also contain the user, additionalUserInfo,
          // and an optional credential (null for email/password)
          // associated with the first factor sign-in.
          // For example, if the user signed in with Google as a first
          // factor, authResult.getAdditionalUserInfo() will contain data
          // related to Google provider that the user signed in with.
          // authResult.getCredential() will contain the Google OAuth
          // credential.
          // authResult.getCredential().getAccessToken() will contain the
          // Google OAuth access token.
          // authResult.getCredential().getIdToken() contains the Google
          // OAuth ID token.
        }
      }
      });

以下程式碼為多重驗證使用者登入的完整範例：

Kotlin+KTX 

FirebaseAuth.getInstance()
    .signInWithEmailAndPassword(email, password)
    .addOnCompleteListener { task ->
        if (task.isSuccessful) {
            // User is not enrolled with a second factor and is successfully
            // signed in.
            // ...
            return@addOnCompleteListener
        }
        if (task.exception is FirebaseAuthMultiFactorException) {
            val multiFactorResolver =
                (task.exception as FirebaseAuthMultiFactorException).resolver

            // Ask user which second factor to use. Then, get
            // the selected hint:
            val selectedHint =
                multiFactorResolver.hints[selectedIndex] as PhoneMultiFactorInfo

            // Send the SMS verification code.
            PhoneAuthProvider.verifyPhoneNumber(
                PhoneAuthOptions.newBuilder()
                    .setActivity(this)
                    .setMultiFactorSession(multiFactorResolver.session)
                    .setMultiFactorHint(selectedHint)
                    .setCallbacks(generateCallbacks())
                    .setTimeout(30L, TimeUnit.SECONDS)
                    .build()
            )

            // Ask user for the SMS verification code, then use it to get
            // a PhoneAuthCredential:
            val credential =
                PhoneAuthProvider.getCredential(verificationId, verificationCode)

            // Initialize a MultiFactorAssertion object with the
            // PhoneAuthCredential.
            val multiFactorAssertion: MultiFactorAssertion =
                PhoneMultiFactorGenerator.getAssertion(credential)

            // Complete sign-in.
            multiFactorResolver
                .resolveSignIn(multiFactorAssertion)
                .addOnCompleteListener { task ->
                    if (task.isSuccessful) {
                        // User successfully signed in with the
                        // second factor phone number.
                    }
                    // ...
                }
        } else {
            // Handle other errors such as wrong password.
        }
    }

Java

FirebaseAuth.getInstance()
  .signInWithEmailAndPassword(email, password)
  .addOnCompleteListener(
      new OnCompleteListener<AuthResult>() {
      @Override
      public void onComplete(@NonNull Task<AuthResult> task) {
        if (task.isSuccessful()) {
          // User is not enrolled with a second factor and is successfully
          // signed in.
          // ...
          return;
        }
        if (task.getException() instanceof FirebaseAuthMultiFactorException) {
          FirebaseAuthMultiFactorException e =
            (FirebaseAuthMultiFactorException) task.getException();

          MultiFactorResolver multiFactorResolver = e.getResolver();

          // Ask user which second factor to use.
          MultiFactorInfo selectedHint =
            multiFactorResolver.getHints().get(selectedIndex);

          // Send the SMS verification code.
          PhoneAuthProvider.verifyPhoneNumber(
            PhoneAuthOptions.newBuilder()
                .setActivity(this)
                .setMultiFactorSession(multiFactorResolver.getSession())
                .setMultiFactorHint(selectedHint)
                .setCallbacks(generateCallbacks())
                .setTimeout(30L, TimeUnit.SECONDS)
                .build());

          // Ask user for the SMS verification code.
          PhoneAuthCredential credential =
            PhoneAuthProvider.getCredential(verificationId, verificationCode);

          // Initialize a MultiFactorAssertion object with the
          // PhoneAuthCredential.
          MultiFactorAssertion multiFactorAssertion =
            PhoneMultiFactorGenerator.getAssertion(credential);

          // Complete sign-in.
          multiFactorResolver
            .resolveSignIn(multiFactorAssertion)
            .addOnCompleteListener(
                new OnCompleteListener<AuthResult>() {
                  @Override
                  public void onComplete(@NonNull Task<AuthResult> task) {
                  if (task.isSuccessful()) {
                    // User successfully signed in with the
                    // second factor phone number.
                  }
                  // ...
                  }
                });
        } else {
          // Handle other errors such as wrong password.
        }
      }
      });

恭喜！您已成功使用多重驗證登入使用者。

後續步驟