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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 M...
developer
microsoft teams
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

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