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KvDaalen's avatar
KvDaalen
Copper Contributor
Mar 11, 2025

MS Teams access token signature is invalid

I am trying to validate an access token from ms teams in my backend application.

The validation fails because the siganture of the token is invalid.

This is how I obtain the token:

export class MyWebPart extends BaseClientSideWebPart {
  protected async onInit(): Promise<void> {
    await super.onInit();
    this.context.sdks.microsoftTeams?.teamsJs.authentication.getAuthToken()
      .then(token => sendToBackend(token));
  }
}

When I copy the token into JWT.io it says that the signature of the token is invalid.

I notice that in the token the issuer is: https://sts.windows.net/{{tenant-id}}/

and in the openid-configuration: https://login.microsoftonline.com/9cd5e2a3-9fa3-456d-9c40-159cf74b23db/v2.0

How do I get a proper token?

developer
microsoft teams

5 Replies

  • KvDaalen's avatar
    KvDaalen
    Copper Contributor
    Mar 13, 2025

    How do I set up my Teams app registration to use the v2.0 endpoint?

    Or is it possible to request the token using the v1 endpoint?

  • KvDaalen's avatar
    KvDaalen
    Copper Contributor
    Mar 12, 2025

    I am using the Teams Toolkit.

    This is the token that I get when I call getAuthToken() when I am previewing my Teams App (F5).

    Where can I update the configuration to get the proper token?

     

  • Prasad_Das-MSFT's avatar
    Prasad_Das-MSFT
    Icon for Microsoft rankMicrosoft
    Mar 12, 2025

    You’re currently using Microsoft Teams SDK to retrieve the token, which is correct. Ensure this token is an ID token or access token signed by Microsoft’s identity platform. Use libraries like jsonwebtoken to validate the token in the backend against Microsoft’s public keys.

    Understanding the Issuer in the Token
    Endpoint Differences:

    Utilizing https://sts.windows.net/{tenantId}/ often refers to tokens issued by Azure AD's v1.0 endpoint, while https://login.microsoftonline.com/{tenantId}/v2.0 refers to tokens issued by the v2.0 endpoint.

    Configuration Matters:

    Ensure the proper setup of your Microsoft Teams app registration to use the v2.0 endpoint if you’re planning to verify tokens against login.microsoftonline.com.

     

     

     

    Thanks, 

    Prasad Das

    ------------------------------------------------------------------------------------------ 

    If the response is helpful, please click "**Mark as Best Response**" and like it. You can share your feedback via Microsoft Teams Developer Feedback link. Click here to escalate. 

     

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