指紋生物識別技術

本文介紹如何將指紋生物辨識加入到通用 Windows 平台 (UWP) 應用程式。 在使用者必須同意特定動作時納入指紋驗證的要求，會增加應用程式的安全性。 例如，在授權應用程式內購買之前，您可能需要指紋驗證，或存取受限制的資源。 指紋驗證是使用 Windows.Security.Credentials.UI 命名空間中的 UserConsentVerifier 類別所管理。

檢查裝置是否有指紋讀取器

若要了解裝置是否有指紋讀取器，請呼叫 UserConsentVerifier.CheckAvailabilityAsync。 即使裝置支援指紋身分驗證，您的應用程式仍應在「設定」中為使用者提供啟用或停用它的選項。

public async System.Threading.Tasks.Task<string> CheckFingerprintAvailability()
{
    string returnMessage = "";

    try
    {
        // Check the availability of fingerprint authentication.
        var ucvAvailability = await Windows.Security.Credentials.UI.UserConsentVerifier.CheckAvailabilityAsync();

        switch (ucvAvailability)
        {
            case Windows.Security.Credentials.UI.UserConsentVerifierAvailability.Available:
                returnMessage = "Fingerprint verification is available.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerifierAvailability.DeviceBusy:
                returnMessage = "Biometric device is busy.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerifierAvailability.DeviceNotPresent:
                returnMessage = "No biometric device found.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerifierAvailability.DisabledByPolicy:
                returnMessage = "Biometric verification is disabled by policy.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerifierAvailability.NotConfiguredForUser:
                returnMessage = "The user has no fingerprints registered. Please add a fingerprint to the " +
                                "fingerprint database and try again.";
                break;
            default:
                returnMessage = "Fingerprints verification is currently unavailable.";
                break;
        }
    }
    catch (Exception ex)
    {
        returnMessage = "Fingerprint authentication availability check failed: " + ex.ToString();
    }

    return returnMessage;
}

請求同意並回傳結果

若要向指紋掃描要求使用者同意，請呼叫 UserConsentVerifier.RequestVerificationAsync 方法。 為了使指紋驗證起作用，使用者必須事先將指紋「簽名」新增至指紋資料庫。

當您呼叫 UserConsentVerifier.RequestVerificationAsync 時，使用者會看到要求指紋掃描的強制回應對話方塊。 您可以向 UserConsentVerifier.RequestVerificationAsync 方法提供一則訊息，該訊息將作為模式對話框的一部分顯示給使用者，如下圖所示。

private async System.Threading.Tasks.Task<string> RequestConsent(string userMessage)
{
    string returnMessage;

    if (String.IsNullOrEmpty(userMessage))
    {
        userMessage = "Please provide fingerprint verification.";
    }

    try
    {
        // Request the logged on user's consent via fingerprint swipe.
        var consentResult = await Windows.Security.Credentials.UI.UserConsentVerifier.RequestVerificationAsync(userMessage);

        switch (consentResult)
        {
            case Windows.Security.Credentials.UI.UserConsentVerificationResult.Verified:
                returnMessage = "Fingerprint verified.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerificationResult.DeviceBusy:
                returnMessage = "Biometric device is busy.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerificationResult.DeviceNotPresent:
                returnMessage = "No biometric device found.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerificationResult.DisabledByPolicy:
                returnMessage = "Biometric verification is disabled by policy.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerificationResult.NotConfiguredForUser:
                returnMessage = "The user has no fingerprints registered. Please add a fingerprint to the " +
                                "fingerprint database and try again.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerificationResult.RetriesExhausted:
                returnMessage = "There have been too many failed attempts. Fingerprint authentication canceled.";
                break;
            case Windows.Security.Credentials.UI.UserConsentVerificationResult.Canceled:
                returnMessage = "Fingerprint authentication canceled.";
                break;
            default:
                returnMessage = "Fingerprint authentication is currently unavailable.";
                break;
        }
    }
    catch (Exception ex)
    {
        returnMessage = "Fingerprint authentication failed: " + ex.ToString();
    }

    return returnMessage;
}