How can I Retrieve Access Token with password credentials in Postman for Azure AD B2C?

Question

Question: What I am trying to perform?
Answer: I am trying to automate the retrieval of Auth Bearer token for API testing

Current Scenario: I have followed this wiki Request Access Token in Postman for Azure AD B2C

I am able to retrieve the Auth Bearer token with Grant Type Implicit. Although, I need to add my username and password in the next step as shown in the image:

If I change the Grant type to Password Credentials to skip manual adding the username and password - the call is successful but it gave an invalid token:

The MFA is enable at the user level. I have created Sign In Sign up flow with MFA Off (although tries both Off and Always On, but it still gave the same invalid token):

How I can bypass the MFA and automate the sign In and retrieve Access Token?

Method 2 : Followed these ROPC way to retrieve the Token

I am able to retrieve the Accesstoken from Postman but If use this token in my Application for REST API calls (Both applications ROPC_Auth App and other application are under the same Tenant B2C), I got an error making a call using this Auth Bearer Token/Access Token : Error Details: enter image description here

Method 3 : If I use the Application/Client ID for the application under the same Tenant which is working manually, I got this error testing the ROPC Flow.

{
    "error": "unauthorized_client",
    "error_description": "AADB2C90057: The provided application is not configured to allow the 'OAuth' Implicit flow.\r\nCorrelation ID: 25661033-61b9-4f59-8358-4cd07ad9b007\r\nTimestamp: 2022-01-13 22:38:52Z\r\n"
}

The troubleshooting part says to change the manifest details, which I did then I got this error

"{

    "error": "invalid_request",

    "error_description": "AADB2C90205: This application does not have sufficient permissions against this web resource to perform the operation.\r\nCorrelation ID: 45dcc3bf-74d6-4536-8ab4-d2025dc9ecb0\r\nTimestamp: 2022-01-13 21:58:57Z\r\n"

}"

Answer 1

• I followed the below documentation link thoroughly as a prerequisite to the ROPC (Resource Owner Password Credential) flow which you were trying to do. I successfully requested an access token, refresh token and ID token through Postman by following the below documentation link correctly for using the ROPC_Auth policy as a user flow for an application registered in Azure AD B2C.

Prerequisite Azure AD B2C link: - https://learn.microsoft.com/en-us/azure/active-directory-b2c/tutorial-create-user-flows?pivots=b2c-custom-policy

ROPC flow Azure AD B2C link: - https://learn.microsoft.com/en-us/azure/active-directory-b2c/add-ropc-policy?tabs=app-reg-ga&pivots=b2c-custom-policy#test-the-ropc-flow

Please find the below snapshots of the successful deployment: -

ROPC_Auth Application in Azure AD B2C

Application Manifest changes: -

Identity Experience framework application in Azure AD B2C: -

Proxy Identity Experience Framework application in Azure AD B2C: -

ROPC_Auth Policy in Azure AD B2C: -

Before requesting tokens through Postman, ensure to run the user flow through the ‘Signup_signin’ B2C custom policy and create a user through it as this user’s credentials created will only be used later in Postman as Password credentials authentication request.

Postman ROPC request: -

Thus, in this way, you can use ‘Password credentials’ flow successfully through Postman to get access token, refresh token and ID token for an application successfully.