Language: HTML | XAML

How to store user credentials (XAML)

Applies to Windows and Windows Phone

The task of storing and retrieving user credentials securely and allowing user credentials roam at no cost with the user's Microsoft account is simplified with the Credential Locker.

For example, you have an app that connects to a service to access protected resources such as media files, or social networking. Your service requires login information for each user. So, you’ve built UI into your app that gets the username and password for the user, which is then used to log the user into the service.

Now you want to go that extra mile for your users and store their login information securely so they don’t have to log in every time they use your app. With a few simple calls to the Credential Locker API, you can store the username and password for your user and easily retrieve them and log the user in the next time they open your app.

Secure storage

The great advantage that Credential Locker brings to your app is that it stores the user credentials in a secure location, and the credential information is encrypted when it’s stored. Sure, you could store your user credentials in a file in the local storage for your app, but storing user credentials in plain text presents a considerable security hole. If a user’s device is compromised in some way, the user’s username and password would be easy to access and manipulate. However, if the username and password are stored using Credential Locker, the best that a malicious source could get a hold of is an encrypted file.

Roaming credentials

As an added benefit to your users, when you store their username and password using Credential Locker, the stored credentials roam with their Microsoft account to any other trusted machine they use with the same Microsoft account. This makes your secure app even more convenient for your users because your app can log them in automatically—without prompting them user for credentials--from any trusted device they have installed your app on and associated with their Microsoft account.

Things work a little differently for domain accounts. If there are credentials stored with your Microsoft account, and you associate that account with a domain account (such as the account that you use at work), your credentials will roam to that domain account. However, any new credentials added when signed on with the domain account won’t roam. This ensures that private credentials for the domain aren’t exposed outside of the domain.

Technologies

Instructions

Step 1: Storing user credentials

Storing user credentials in the Credential Locker is a quick, two-step process.

  1. Obtain a reference to the Credential Locker using the PasswordVault object from the Windows.Security.Credentials namespace.
  2. Create a PasswordCredential object that contains an identifier for your app, the username and the password, and pass that to the PasswordVault.Add method to add the credential to the locker.

var vault = new Windows.Security.Credentials.PasswordVault();
vault.Add(new Windows.Security.Credentials.PasswordCredential(
    "My App", username, password));


Step 2: Retrieving user credentials

You have several options for retrieving user credentials from the Credential Locker after you have a reference to the PasswordVault object.

  • You can retrieve all the credentials the user has supplied for your app in the locker with the PasswordVault.RetrieveAll method.

  • If you know the username for the stored credentials, you can retrieve all the credentials for that username with the PasswordVault.FindAllByUserName method.

  • If you know the resource name for the stored credentials, you can retrieve all the credentials for that resource name with the PasswordVault.FindAllByResource method.

  • Finally, if you know both the username and the resource name for a credential, you can retrieve just that credential with the PasswordVault.Retrieve method.

Let’s look at an example where we have stored the resource name globally in an app and we log the user on automatically if we find a credential for them. If we find multiple credentials for the same user, we ask the user to select a default credential to use when logging on.


private string resourceName = "My App";
private string defaultUserName;

private void Login()
{
    var loginCredential = GetCredentialFromLocker();

    if (loginCredential != null)
    {
        // There is a credential stored in the locker.
        // Populate the Password property of the credential
        // for automatic login.
        loginCredential.RetrievePassword();
    }
    else
    {
        // There is no credential stored in the locker.
        // Display UI to get user credentials.
        loginCredential = GetLoginCredentialUI();
    }

    // Log the user in.
    ServerLogin(loginCredential.UserName, loginCredential.Password);
}


private Windows.Security.Credentials.PasswordCredential GetCredentialFromLocker()
{
    Windows.Security.Credentials.PasswordCredential credential = null;

    var vault = new Windows.Security.Credentials.PasswordVault();
    var credentialList = vault.FindAllByResource(resourceName);
    if (credentialList.Count > 0)
    {
        if (credentialList.Count == 1)
        {
            credential = credentialList[0];
        }
        else
        {
            // When there are multiple usernames,
            // retrieve the default username. If one doesn’t
            // exist, then display UI to have the user select
            // a default username.

            defaultUserName = GetDefaultUserNameUI();

            credential = vault.Retrieve(resourceName, defaultUserName);
        }
    }

    return credential;
}


Step 3: Deleting user credentials

Deleting user credentials in the Credential Locker is also a quick, two-step process.

  1. Obtain a reference to the Credential Locker using the PasswordVault object from the Windows.Security.Credentials namespace.

  2. Pass the credential you want to delete to the PasswordVault.Remove method.


var vault = new Windows.Security.Credentials.PasswordVault();
vault.Remove(new Windows.Security.Credentials.PasswordCredential(
    "My App", username, password));


Remarks

As you can see, the Credential Locker is an easy-to-use feature that simplifies your task of authenticating users and storing those user credentials for future use—all in a highly secure fashion.

Other app authentication topics include the Web Authentication Broker, which you can use to retrieve an authentication token from a website (for example, OAuth), and personalizing your app based on a user’s Microsoft account.

Best practices

Only use the credential locker for passwords and not for larger data blobs.

Save passwords in the credential locker only if the following criteria are met:

  • The user has successfully signed in.
  • The user has opted to save passwords.

Related topics

Credential Locker sample
Authentication and User Identity
Windows.Security.Credentials

 

 

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