Yggdrasil Authentication Model

• Yggdrasil Authentication Model
  • Initialize validator
  • Get authentication results
  • Interpret authentication results
    • Failed authentication result
    • Successful authentication result

This authentication model implements an older version of Mojang's authentication scheme, which is now deprecated.

WARNING

Continuing to use this model for verification of official accounts will be considered an invalid request. But the model can still be used to log in to servers that use third-party authentication services (such as AuthLib-Injector).

Initialize validator

You can initialize the offline validator with the following code:

var yggdrasilAuthenticator = new YggdrasilAuthenticator
{
    AuthServer = "[CUSTOM_AUTH_SERVER]",
    Email = "[EMAIL],
    LauncherAccountParser = launcherAccountParser,
    Password = "[PASSWORD]"
};

In the above code block, please replace these parameters according to your actual situation:

Project	Description
launcherAccountParser	For initialization of the launcher account parser, see here
[CUSTOM_AUTH_SERVER]	Optional field, custom authentication server address. This field is usually provided by a third-party authentication service provider. If not filled in, Mojang's official authentication server address will be used
[EMAIL]	Email address to verify account
[PASSWORD]	Password to verify account

TIP

For the initialization of launcherAccountParser (game profile parser), please refer to the Game Profile Parser page

WARNING

When using a third-party authentication server, use the https:// rather than the http:// protocol to connect to the authentication server. Using an insecure authentication server may lead to sensitive data leakage and other issues.

Get authentication results

After you complete the initialization of the authentication model, you only need to call the authentication method of the offline verifier to complete the account authentication.

In an asynchronous context, use AuthTaskAsync to accomplish authentication:

var authResult = await offlineAuthenticator.AuthTaskAsync(false);

In a sync context, use Auth to finish authentication:

var authResult = offlineAuthenticator.Auth();

Interpret authentication results

After the authentication method is completed, the authentication model will return the authentication result, which is of the parent type AuthResultBase object. All authentication results contain an enumeration value AuthStatus, which directly indicates the success or failure of the authentication result. Below you can see an interpretation of the authentication results:

Failed authentication result

By judging whether Error is empty, you can easily judge whether the authentication results returned by the authentication model are valid. The Error object will contain the following fields to tell you some details:

Field	Description
authResult.Error.Cause	The specific cause of the problem
authResult.Error.Error	error name
authResult.Error.ErrorMessage	Details of the error, possibly including a solution

Successful authentication result

If the Error field in the authentication result is empty, it means that the authentication is valid. A successful authentication result will contain the following information:

Field	Description
authResult.Id	The unique identifier of the username, ProjBobcat uses a specific generation method to generate this identifier
authResult.AccessToken	Authorization credentials for the user account
authResult.Profiles	List of roles available to the user, which may contain multiple available roles
authResult.SelectedProfile	The role currently selected by the user. This field may be empty. If it is empty, the user needs to be prompted for manual selection.
authResult.User	Summary of user account information, including some basic account information
authResult.LocalId	Local ID, usually a randomly generated UUID
authResult.RemoteId	The remote ID returned by the authentication server, usually a unique identifier for the user