Login and Authentication
Objective
This section defines the minimum requirements for the login and two-factor authentication (2FA) flow, ensuring secure, clear, and accessible access to the sales environment, based on UX best practices and data protection standards.
Insights
Authentication structure should be compatible with offline contexts (e.g., reconnection handling, secure caching) where applicable.
This flow must comply with security regulations required for proximity-based payments via NFC (e.g., PCI MPoC).
Login Screen with Empty Fields
01 - Email and password fields
Must appear empty with clear placeholders (e.g., [email protected], Password123@)
Mandatory:
The “Login” button must only be enabled when both fields are correctly completed.
Recommended:
Include a “Forgot your password?” link for recovery.
Login Screen with Credentials Filled
02 - “Login” button (enabled)
Must be visually highlighted. Tapping it initiates sending a verification code to the registered email.
Mandatory:
Provide immediate visual feedback when the button is tapped (e.g., loading animation).
Recommended:
Include a confirmation cue (visual or audio) after login attempt.
Two-Factor Authentication (2FA) Code Entry
03 - Security info message
Must inform the user that a verification code has been sent to their email, partially masked (us****@email.com)
04 - Code input fields (6 digits)
Must support auto-advance on input and visual feedback per digit.
Mandatory:
Show countdown timer to resend the code (e.g., “Resend code in 00:30”)
Recommended:
Automatically validate the code once all digits are entered.
Code Fully Entered
05 - Complete 2FA code
Must automatically enable the “Login” button once all digits are valid
Mandatory:
After code validation, user must be redirected to the sales environment.
Recommended:
Use smooth visual transitions to reinforce successful authentication.
Access to Sales Environment
Show the sales home screen. This screen must display:
Vendor name and photo
Search bar
Product list with name, category, price, stock
Bottom navigation bar with visible sections: Home, Cart, Charge, User
Mandatory:
Navigation is only accessible after full credential + code validation.
Recommended:
Customize this screen with relevant info based on vendor profile.
Each component and user experience of the sales screen will be discussed in more detail in the next session.
Mandatory Messages
When the code is incorrect:
Invalid code. Please check the number sent to your email and try again.
When the code expires:
Code expired. Please request a new one to continue.
Expected Behaviors
The app must provide visual and/or audio feedback at each stage.
The “Login” button must respect validation logic.
Two-factor authentication is mandatory before accessing the sales system.
Sensitive data (email, password) must be handled with masking and encryption, in accordance with LGPD and PCI standards.
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