Web API を呼び出すデスクトップアプリ: ユーザー名とパスワードでトークンを取得する

[アーティクル]
01/15/2024

デスクトップアプリケーションでは、リソース所有者パスワード認証情報と呼ばれるユーザー名とパスワードのフローを使ってサイレントにトークンを取得できます。

警告

ユーザー名とパスワードのフローは 非推奨 です。アプリケーションがユーザーに直接パスワードを尋ねることになり、これは安全でないパターンとなります。 ROPC フローによって発生するリスクと課題の詳細については、「パスワードの増大する問題の解決策は何ですか?」を参照してください。

さらに、ユーザー名とパスワードを使用することで、開発者は次のような多くのことを放棄します。

現代のアイデンティティの基本原則 - パスワードはフィッシングされて再生される可能性があります。共有された秘密は傍受される可能性があるためです。
多要素認証（MFA）- 相互作用がないため、ユーザーはサインインできません。
シングルサインオン (SSO) 機能。

ユーザー名とパスワードのフローには、次の制約もあります。

ユーザー名とパスワードのフローは、条件付きアクセスおよび多要素認証との互換性がありません。ほとんどの組織が行うように、テナント管理者が多要素認証を必要とする Microsoft Entra でアプリを実行する場合は、このフローを使用できません。
職場および学校アカウントにのみ有効です。個別のMicrosoft アカウントではありません。
このフローは、.NET デスクトップと .NET で使用できますが、UWP では使用できません。

DevOps シナリオなど、場合によっては、ユーザー名とパスワードを使用すると便利です。ただし、独自の UI を提供する対話型のシナリオでユーザー名とパスワードを使用したい場合は、避けることを考慮してください。

Windows でトークンをサイレントモードで取得するための推奨フローは、Windows 認証ブローカーを使用することです。または、開発者は、Web ブラウザーにアクセスせずにデバイスでデバイスコードフローを使用することもできます。

リソース所有者パスワード資格情報 (ROPC) フローを使用してソーシャル ID を持つユーザーをサインインさせるデスクトップアプリケーションを構築する場合は、Azure AD B2C を使用してソーシャル ID を持つユーザーをサインインする方法を参照してください

ROPC フローを使用する

IPublicClientApplication にはメソッド AcquireTokenByUsernamePassword が含まれています。

次のサンプルは、シンプルなケースを示しています。

static async Task GetATokenForGraph()
{
 string authority = "https://login.microsoftonline.com/contoso.com";
 string[] scopes = new string[] { "user.read" };
 IPublicClientApplication app;
 app = PublicClientApplicationBuilder.Create(clientId)
       .WithAuthority(authority)
       .Build();
 var accounts = await app.GetAccountsAsync();

 AuthenticationResult result = null;
 if (accounts.Any())
 {
  result = await app.AcquireTokenSilent(scopes, accounts.FirstOrDefault())
                    .ExecuteAsync();
 }
 else
 {
  try
  {
   var securePassword = new SecureString();
   foreach (char c in "dummy")        // you should fetch the password
    securePassword.AppendChar(c);  // keystroke by keystroke

   result = await app.AcquireTokenByUsernamePassword(scopes,
                                                    "joe@contoso.com",
                                                     securePassword)
                      .ExecuteAsync();
  }
  catch(MsalException)
  {
   // See details below
  }
 }
 Console.WriteLine(result.Account.Username);
}

次のサンプルは、最新のケース (および取得可能な例外の種類の説明とその軽減策) を示しています。

static async Task GetATokenForGraph()
{
 string authority = "https://login.microsoftonline.com/contoso.com";
 string[] scopes = new string[] { "user.read" };
 IPublicClientApplication app;
 app = PublicClientApplicationBuilder.Create(clientId)
                                   .WithAuthority(authority)
                                   .Build();
 var accounts = await app.GetAccountsAsync();

 AuthenticationResult result = null;
 if (accounts.Any())
 {
  result = await app.AcquireTokenSilent(scopes, accounts.FirstOrDefault())
                    .ExecuteAsync();
 }
 else
 {
  try
  {
   var securePassword = new SecureString();
   foreach (char c in "dummy")        // you should fetch the password keystroke
    securePassword.AppendChar(c);  // by keystroke

   result = await app.AcquireTokenByUsernamePassword(scopes,
                                                    "joe@contoso.com",
                                                    securePassword)
                    .ExecuteAsync();
  }
  catch (MsalUiRequiredException ex) when (ex.Message.Contains("AADSTS65001"))
  {
   // Here are the kind of error messages you could have, and possible mitigations

   // ------------------------------------------------------------------------
   // MsalUiRequiredException: AADSTS65001: The user or administrator has not consented to use the application
   // with ID '{appId}' named '{appName}'. Send an interactive authorization request for this user and resource.

   // Mitigation: you need to get user consent first. This can be done either statically (through the portal),
   /// or dynamically (but this requires an interaction with Azure AD, which is not possible with
   // the username/password flow)
   // Statically: in the portal by doing the following in the "API permissions" tab of the application registration:
   // 1. Click "Add a permission" and add all the delegated permissions corresponding to the scopes you want (for instance
   // User.Read and User.ReadBasic.All)
   // 2. Click "Grant/revoke admin consent for <tenant>") and click "yes".
   // Dynamically, if you are not using .NET (which does not have any Web UI) by
   // calling (once only) AcquireTokenInteractive.
   // remember that Username/password is for public client applications that is desktop/mobile applications.
   // If you are using .NET or don't want to call AcquireTokenInteractive, you might want to:
   // - use device code flow (See https://aka.ms/msal-net-device-code-flow)
   // - or suggest the user to navigate to a URL to consent: https://login.microsoftonline.com/common/oauth2/v2.0/authorize?client_id={clientId}&response_type=code&scope=user.read
   // ------------------------------------------------------------------------

   // ------------------------------------------------------------------------
   // ErrorCode: invalid_grant
   // SubError: basic_action
   // MsalUiRequiredException: AADSTS50079: The user is required to use multi-factor authentication.
   // The tenant admin for your organization has chosen to oblige users to perform multi-factor authentication.
   // Mitigation: none for this flow
   // Your application cannot use the Username/Password grant.
   // Like in the previous case, you might want to use an interactive flow (AcquireTokenInteractive()),
   // or Device Code Flow instead.
   // Note this is one of the reason why using username/password is not recommended;
   // ------------------------------------------------------------------------

   // ------------------------------------------------------------------------
   // ex.ErrorCode: invalid_grant
   // subError: null
   // Message = "AADSTS70002: Error validating credentials.
   // AADSTS50126: Invalid username or password
   // In the case of a managed user (user from an Azure AD tenant opposed to a
   // federated user, which would be owned
   // in another IdP through ADFS), the user has entered the wrong password
   // Mitigation: ask the user to re-enter the password
   // ------------------------------------------------------------------------

   // ------------------------------------------------------------------------
   // ex.ErrorCode: invalid_grant
   // subError: null
   // MsalServiceException: ADSTS50034: To sign into this application the account must be added to
   // the {domainName} directory.
   // or The user account does not exist in the {domainName} directory. To sign into this application,
   // the account must be added to the directory.
   // The user was not found in the directory
   // Explanation: wrong username
   // Mitigation: ask the user to re-enter the username.
   // ------------------------------------------------------------------------
  }
  catch (MsalServiceException ex) when (ex.ErrorCode == "invalid_request")
  {
   // ------------------------------------------------------------------------
   // AADSTS90010: The grant type is not supported over the /common or /consumers endpoints.
   // Please use the /organizations or tenant-specific endpoint.
   // you used common.
   // Mitigation: as explained in the message from Azure AD, the authority you use in the application needs
   // to be tenanted or otherwise "organizations". change the
   // "Tenant": property in the appsettings.json to be a GUID (tenant Id), or domain name (contoso.com)
   // if such a domain is registered with your tenant
   // or "organizations", if you want this application to sign-in users in any Work and School accounts.
   // ------------------------------------------------------------------------

  }
  catch (MsalServiceException ex) when (ex.ErrorCode == "unauthorized_client")
  {
   // ------------------------------------------------------------------------
   // AADSTS700016: Application with identifier '{clientId}' was not found in the directory '{domain}'.
   // This can happen if the application has not been installed by the administrator of the tenant or consented
   // to by any user in the tenant.
   // You may have sent your authentication request to the wrong tenant
   // Cause: The clientId in the appsettings.json might be wrong
   // Mitigation: check the clientId and the app registration
   // ------------------------------------------------------------------------
  }
  catch (MsalServiceException ex) when (ex.ErrorCode == "invalid_client")
  {
   // ------------------------------------------------------------------------
   // AADSTS70002: The request body must contain the following parameter: 'client_secret or client_assertion'.
   // Explanation: this can happen if your application was not registered as a public client application in Azure AD
   // Mitigation: in the Azure portal, edit the manifest for your application and set the `allowPublicClient` to `true`
   // ------------------------------------------------------------------------
  }
  catch (MsalServiceException)
  {
   throw;
  }

  catch (MsalClientException ex) when (ex.ErrorCode == "unknown_user_type")
  {
   // Message = "Unsupported User Type 'Unknown'. Please see https://aka.ms/msal-net-up"
   // The user is not recognized as a managed user, or a federated user. Azure AD was not
   // able to identify the IdP that needs to process the user
   throw new ArgumentException("U/P: Wrong username", ex);
  }
  catch (MsalClientException ex) when (ex.ErrorCode == "user_realm_discovery_failed")
  {
   // The user is not recognized as a managed user, or a federated user. Azure AD was not
   // able to identify the IdP that needs to process the user. That's for instance the case
   // if you use a phone number
   throw new ArgumentException("U/P: Wrong username", ex);
  }
  catch (MsalClientException ex) when (ex.ErrorCode == "unknown_user")
  {
   // the username was probably empty
   // ex.Message = "Could not identify the user logged into the OS. See https://aka.ms/msal-net-iwa for details."
   throw new ArgumentException("U/P: Wrong username", ex);
  }
  catch (MsalClientException ex) when (ex.ErrorCode == "parsing_wstrust_response_failed")
  {
   // ------------------------------------------------------------------------
   // In the case of a Federated user (that is owned by a federated IdP, as opposed to a managed user owned in an Azure AD tenant)
   // ID3242: The security token could not be authenticated or authorized.
   // The user does not exist or has entered the wrong password
   // ------------------------------------------------------------------------
  }
 }

 Console.WriteLine(result.Account.Username);
}

AcquireTokenByUsernamePassword に適用できるすべての修飾子の詳細については、AcquireTokenByUsernamePasswordParameterBuilder に関する記事を参照してください。

次の抜粋は、MSAL Java コードサンプルから取得したものです。

 PublicClientApplication pca = PublicClientApplication.builder(clientId)
                .authority(authority)
                .build();

        //Get list of accounts from the application's token cache, and search them for the configured username
        //getAccounts() will be empty on this first call, as accounts are added to the cache when acquiring a token
        Set<IAccount> accountsInCache = pca.getAccounts().join();
        IAccount account = getAccountByUsername(accountsInCache, username);

        //Attempt to acquire token when user's account is not in the application's token cache
        IAuthenticationResult result = acquireTokenUsernamePassword(pca, scope, account, username, password);
        System.out.println("Account username: " + result.account().username());
        System.out.println("Access token:     " + result.accessToken());
        System.out.println("Id token:         " + result.idToken());
        System.out.println();

        accountsInCache = pca.getAccounts().join();
        account = getAccountByUsername(accountsInCache, username);

        //Attempt to acquire token again, now that the user's account and a token are in the application's token cache
        result = acquireTokenUsernamePassword(pca, scope, account, username, password);
        System.out.println("Account username: " + result.account().username());
        System.out.println("Access token:     " + result.accessToken());
        System.out.println("Id token:         " + result.idToken());
    }

    private static IAuthenticationResult acquireTokenUsernamePassword(PublicClientApplication pca,
                                                                      Set<String> scope,
                                                                      IAccount account,
                                                                      String username,
                                                                      String password) throws Exception {
        IAuthenticationResult result;
        try {
            SilentParameters silentParameters =
                    SilentParameters
                            .builder(scope)
                            .account(account)
                            .build();
            // Try to acquire token silently. This will fail on the first acquireTokenUsernamePassword() call
            // because the token cache does not have any data for the user you are trying to acquire a token for
            result = pca.acquireTokenSilently(silentParameters).join();
            System.out.println("==acquireTokenSilently call succeeded");
        } catch (Exception ex) {
            if (ex.getCause() instanceof MsalException) {
                System.out.println("==acquireTokenSilently call failed: " + ex.getCause());
                UserNamePasswordParameters parameters =
                        UserNamePasswordParameters
                                .builder(scope, username, password.toCharArray())
                                .build();
                // Try to acquire a token via username/password. If successful, you should see
                // the token and account information printed out to console
                result = pca.acquireToken(parameters).join();
                System.out.println("==username/password flow succeeded");
            } else {
                // Handle other exceptions accordingly
                throw ex;
            }
        }
        return result;
    }

この抜粋は、MSAL ノード dev サンプルから取得したものです。次のコードスニペットでは、ユーザー名とパスワードは、説明のためにのみハードコード化されています。運用環境では避ける必要があります。代わりに、ユーザーに自分のユーザー名とパスワードの入力を求める基本的な UI を使用することをお勧めします。

const msal = require("@azure/msal-node");

const msalConfig = {
    auth: {
        clientId: "your_client_id_here",
        authority: "your_authority_here",
    }
};

const pca = new msal.PublicClientApplication(msalConfig);

// For testing, enter your username and password below.
// In production, replace this with a UI prompt instead.
const usernamePasswordRequest = {
    scopes: ["user.read"],
    username: "", // Add your username here
    password: "", // Add your password here
};

pca.acquireTokenByUsernamePassword(usernamePasswordRequest).then((response) => {
    console.log("acquired token by password grant");
}).catch((error) => {
    console.log(error);
});

この抜粋は、MSAL Python dev サンプルから取得したものです。

# Create a preferably long-lived app instance which maintains a token cache.
app = msal.PublicClientApplication(
    config["client_id"], authority=config["authority"],
    # token_cache=...  # Default cache is in memory only.
                       # You can learn how to use SerializableTokenCache from
                       # https://msal-python.rtfd.io/en/latest/#msal.SerializableTokenCache
    )

# The pattern to acquire a token looks like this.
result = None

# Firstly, check the cache to see if this end user has signed in before
accounts = app.get_accounts(username=config["username"])
if accounts:
    logging.info("Account(s) exists in cache, probably with token too. Let's try.")
    result = app.acquire_token_silent(config["scope"], account=accounts[0])

if not result:
    logging.info("No suitable token exists in cache. Let's get a new one from AAD.")
    # See this page for constraints of Username Password Flow.
    # https://github.com/AzureAD/microsoft-authentication-library-for-python/wiki/Username-Password-Authentication
    result = app.acquire_token_by_username_password(
        config["username"], config["password"], scopes=config["scope"])

次のステップ

このシナリオの次の記事である「デスクトップアプリから Web API を呼び出す」に進みます。

Web API を呼び出すデスクトップ アプリ: ユーザー名とパスワードでトークンを取得する

ROPC フローを使用する

次のステップ

その他のリソース

Web API を呼び出すデスクトップアプリ: ユーザー名とパスワードでトークンを取得する