Windows 8 User Credentials

credentials.js

var CREDENTIAL_NAME = "<Your Credential Resource Name>";

var signin = new WinJS.Promise(function (comp, err) {
    var vault = new Windows.Security.Credentials.PasswordVault();

    var credential;
    try {
        var stored = vault.findAllByResource(CREDENTIAL_NAME);
        if (stored.length > 0) {
            stored = stored[0];

            // Retrieve the full stored credential
            stored = vault.retrieve(CREDENTIAL_NAME, stored.userName);
            credential = {
                user: stored.userName,
                password: stored.password
            };
        }
    } catch (e) {
        // Could not find credential
    }

    if (credential) {
        // Found saved credential
        return comp(credential);
    }

    // Prompt the user for a password
    var opts = new Windows.Security.Credentials.UI.CredentialPickerOptions();
    opts.authenticationProtocol = Windows.Security.Credentials.UI.AuthenticationProtocol.basic;
    opts.caption = "<Caption>";
    opts.message = "<Message>";
    opts.credentialSaveOption = Windows.Security.Credentials.UI.CredentialSaveOption.unselected;
    opts.callerSavesCredential = true;
    opts.targetName = ".";

    var picker = Windows.Security.Credentials.UI.CredentialPicker.pickAsync(opts);
    picker.then(function (result) {
        if (result.credential == null) {
            // User canceled
            return err();
        }

        if (result.credentialSaveOption === Windows.Security.Credentials.UI.CredentialSaveOption.selected) {
            vault.add(new Windows.Security.Credentials.PasswordCredential(
                CREDENTIAL_NAME, result.credentialUserName, result.credentialPassword));
        }

        comp({
            user: result.credentialUserName,
            password: result.credentialPassword
        });
    }, err);
})