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github-actions edited this page Mar 10, 2023 · 9 revisions

VPN Authentication in-app

This page describes how the implementation for the authentication in-app works in the Mozilla VPN client.

To know more about the FxA authentication flow, see the official FxA API documentation

Authentication methods

The authentication is triggered by the frontend component, calling the method VPN.authenticate(). The client picks the right authentication method based on what is supported by the current platform. There are mainly 3 methods. The current configuration for 2.8 is the following:

  • Android: in-app authentication with account creation
  • iOS: in-app authentication with account creation
  • Linux: web-based authentication
  • Windows: in-app authentication without account creation
  • MacOS: in-app authentication without account creation.

In-app authentication with account creation

The client allows sign-in and sign-up.

In-app authentication without account creation

The client allows the sign-in. But if the account doesn’t exist, instead of starting the account creation in-app, the flow continues in the browser as we used to do in previous versions.

Web-based authentication

This flow is what we currently use in v2.7 and previous versions.

Finite State machine

The authentication flow can be seen and implemented as a finite state machine. The states are described in the next sections, For each state, we have a list of error codes to describe what goes wrong. At the end of this document, you can read the list of all the error codes. On top of these errors, we have the main ones such as “No internet connection”.

Almost all the states have a call to action (write the email address or the password, or the 6-digit codes, etc). After this, the frontend code must call one or more available methods (see the list per states) to move to the next state or to trigger an error.

State: Initializing

This is an internal state in which the VPN client communicates with the guardian-website to start the process. If there are no connectivity issues, this state takes almost nothing to be completed. From here, we go to Start.

  • Next states: Start
  • Errors: none
  • Available methods: none

State: Start

This state is the starting point for the in-app authentication flow. In this state, the client asks for the email address. The tasks for this state are:

  • Obtain the email address
  • Validate the email address
  • Process the email address

When the email address is received and validated, the client goes to Checking-account state.

  • Next states: Checking-account
  • Errors:
    • Unknown account - the account does not exist anymore. Super rare.
    • Service unavailable - FxA is down
    • Email can not be used to login - FxA is blocking the account
    • Account already exists - rare
    • Email already exists - rare
    • Email type not supported - ?!?
    • Invalid email address
    • Invalid email code
    • Too many requests
    • Unknown account - ?!?
  • Available methods:
    • MZAuthInApp.checkAccount(emailAddress)
    • MZAuthInApp.validateEmailAddress(emailAddress) -> bool

State: Checking-account

This state does not require user-interaction. The state machine is completing the checkAccount() operation. This operation can take a few seconds (usually less).

If the account exists, we go to Sign-in, otherwise, for a new account, we go to Sign-up or fallback in the browser, in case the authentication method is “without account creation”.

  • Next states: Sign-in, Sign-up, fallback in the browser
  • Errors: none
  • Available methods: none

State: Sign-in

The client asks for the password. Then, it goes to the Signing-in state.

  • Next states: Signing-in
  • Errors:
    • Incorrect password
    • Too many requests
    • Request Timeout
    • Sign in with this email type is not currently supported -This is a strange FxA code. We have to investigate how to reproduce it.
    • Failed to send email - the unblock code is needed but the email sending failed.
  • Available methods:
    • MZAuthInApp.setPassword(password)
    • MZAuthInApp.signIn()

State: Signing-in

The client interacts with FxA. This should take a few seconds (usually less). From here we can go to several states:

  • Sign-in: Something went wrong. Check the error codes.
  • Unblock code needed: FxA requires an extra validation step. An email is sent to the user with a 6-digit code.
  • TOTP verification needed: the account is configured to use TOTP (double factor authentication). The user needs to submit a 6-digit code.
  • Finalize: the authentication is ready to be finalized
  • Next states: Unblock code needed, TOTP verification needed, Finalize
  • Errors: none
  • Available methods: none

State: Unblock code needed

This state is shown if FxA “doesn’t trust” the account or the user enough. An email is sent to the user’s email address with a 6-digit code. In this state, the client needs to inform the user and ask for this 6-digit code.

If needed, the user can ask to have a new email code. See: MZAuthInApp.resendUnblockCodeEmail().

From here we can go to Verifying unblock code.

  • Next states: Verifying unblock code
  • Errors: none
    • Invalid unblock code
    • Too many requests
  • Available methods:
    • MZAuthInApp.verifyUnblockCode(code)
    • MZAuthInApp.resendUnblockCodeEmail()

State: Verifying unblock code

The client is sending the unblock code to FxA. We are waiting for the result of the validation. From here, we can go to Finalize or back to Unblock code needed in case the code is invalid.

From here we can go to Finalize, or Unblock code needed in case the code is invalid.

  • Next states: Unblock code needed, Finalize
  • Errors: none
  • Available methods: none

State: TOTP verification needed

If the account is configured to use TOTP, we are in this state after the Sign-in. The client needs to inform the user and asks for the 6-digit code. From here, we go to Verifying session TOTP code.

  • Next states: Verifying session TOTP code
  • Errors: none
    • Invalid TOTP code
  • Available methods:
    • MZAuthInApp.verifySessionTotpCode(code)

State: Verifying session TOTP code

The client is sending the TOTP code to FxA. We are waiting for the result of the validation. From here, we can go to Finalize or back to TOTP verification needed in case the code is invalid.

  • Next states: TOTP verification needed, Finalize
  • Errors: none
  • Available methods: none

State: Sign-Up

In case we need to create a new account, we land in this state. In this state we need to run a few steps:

  • Ask for the password (this is the only thing we really care)
  • Ask for other “legal” things (age, terms of service checkbox…)
  • Validate the password:
    • The password cannot be a common one (there is a list from FxA)
    • The password must be at least 8 digits
    • The password cannot contain the account email address
  • Create the account

From here we go to the Signing-up state where the real operation is done.

  • Next states: Signing-up
  • Errors: none
  • Available methods:
    • MZAuthInApp.validatePasswordCommons(password) -> bool
    • MZAuthInApp.validatePasswordLength(password) -> bool
    • MZAuthInApp.validatePasswordEmail(password) -> bool
    • MZAuthInApp.setPassword(password)
    • MZAuthInApp.signUp()

State: Signing-up

The account creation requires email validation. The user receives a 6-digit code via email. If this is needed, we go to Email validation. If an error occur, we go back to Start.

  • Next states: Start, Email validation
  • Errors: none
  • Available methods: none

State: Email validation

This state is super super similar to the “Unblock code needed” one, but, because this is a different FxA concept, we want to keep the 2 separate. The behavior is exactly the same: the user needs to insert a 6-digit code and then we go to Verifying session email code.

If needed, the user can ask for a new session code email. See MZAuthInApp.resendVerificationSessionCodeEmail().

  • Next states: Verifying session email code
  • Errors:
    • Invalid or expired verification code
    • Too many requests
  • Available methods:
    • MZAuthInApp.verifySessionEmailCode(code)
    • MZAuthInApp.resendVerificationSessionCodeEmail()

State: Verifying session email code

The FxA is performing the email code verification. In case of an error, we go back to Email validation, otherwise, we go to Finalize.

  • Next states: Email validation, Finalize
  • Errors: none
  • Available methods: none

State: Finalize

This is the last state if all works fine. The authentication is ready to be finalized. This step contains a few network requests to obtain the session code. After that, the authentication is finally completed.

Implementation-wise, this state does not exist, because, instead of landing here, we dismiss the authentication component and we show the main VPN view.

If this authentication flow requires the account deletion, the next step is the Account Deletion Request.

  • Next states: Account Deletion Request
  • Errors:
    • Authentication failure
  • Available methods: none

State: Account Deletion Request

If the account deletion is requested, in this state the client asks the user to accept a few things. Then the account deletion can proceed.

  • Next Step: Deleting account
  • Errors: none
  • Available methods:
    • MZAuthInApp.deleteAccount()

State: Deleting account

This is the final step for the account deletion. After that, you can see an error, or a success.

  • Next Step: none
  • Errors: none
  • Available methods: none

State: fallback in the browser

In case the authentication method is “without account creation”, we land here. The authentication continues in the browser as we used to do in v2.7.

  • Next states: none
  • Errors:
    • Authentication failure
  • Available methods: none

Errors

  • Account already exists
  • Email already exists
  • Email can not be used to login
  • Email type not supported
  • Failed to send email
  • Incorrect password
  • Invalid email code
  • Invalid or expired verification code
  • Invalid unblock code
  • Invalid TOTP code
  • Too many requests
  • Server unavailable
  • Request Timeout
  • Unknown account

The whole flow

stateDiagram-v2
  Start: Start
  CheckingAccount: Checking Account
  SignIn: Sign In
  SignUp: Sign Up
  Fallback: Fallback in the browser
  SigningIn: Signing In
  SigningUp: Signing Up
  UnblockCodeNeeded: Unblock code needed
  VerifyingUnblockCode: Verifying unblock code
  TOTPVerificationNeeded: TOTP verification needed
  VerifyingSessionTOTPCode: Verifying session TOTP code
  EmailVerification: Email verification
  VerifyingSessionEmailCode: Verifying session email code
  state signing_results <<choice>>
  AccountDeletionRequest: Account deletion request
  DeletingAccount: Deleting account

  Initializing --> Start
  Start --> CheckingAccount: email address received
  CheckingAccount --> SignIn: the account already exists
  CheckingAccount --> SignUp: new account is required
  CheckingAccount --> Fallback: new account is required
  SignIn --> SigningIn: password received
  SigningIn --> signing_results
  signing_results --> SignIn: invalid password or error
  signing_results --> UnblockCodeNeeded: unblock code required
  signing_results --> TOTPVerificationNeeded: TOTP code required
  signing_results --> Finalize: authentication completed
  UnblockCodeNeeded --> VerifyingUnblockCode: Unblock code received
  VerifyingUnblockCode --> signing_results: authentication completed
  VerifyingUnblockCode --> UnblockCodeNeeded: Unblock code invalid or error
  TOTPVerificationNeeded --> VerifyingSessionTOTPCode: TOTP code received
  VerifyingSessionTOTPCode --> signing_results: authentication completed
  VerifyingSessionTOTPCode --> TOTPVerificationNeeded: TOTP code invalid or error
  SignUp --> SigningUp: password received
  SigningUp --> EmailVerification: email sent
  SigningUp --> Start: error
  EmailVerification --> VerifyingSessionEmailCode: email code received
  VerifyingSessionEmailCode --> Finalize: authentication completed
  VerifyingSessionEmailCode --> EmailVerification: code invalid or error
  Finalize --> AccountDeletionRequest: account deletion is requested
  AccountDeletionRequest --> DeletingAccount: account deleted
  DeletingAccount --> Finalize: Operation is completed
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