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Project / in progress
Native Android platform deployed on PAX smart POS devices to enable distributed banking services across commercial agents nationwide.
Role
Senior Android Engineer
Status
in progress
Overview
Designed and developed a secure native Android platform for BANPRO’s agent banking network, enabling commercial establishments across Nicaragua to operate as distributed banking agents. The application provides access to a broad range of financial services including remittances, bill payments, money transfers, cash withdrawals, government payments, and other banking agreements directly from PAX smart POS devices.
Architecture
Native Android architecture built with Kotlin, Jetpack Compose, MVVM, Clean Architecture, Hilt, Retrofit, Room, and DataStore. Security-focused implementation following enterprise mobile security best practices, including secure communication, protected local storage, and runtime integrity controls.
Tech Stack
Backend
Frontend
Infrastructure
Integration
Database
Security
Key Contributions
Designed the modular architecture for large-scale distributed banking services.
Implemented secure authentication and API communication flows.
Integrated multiple banking agreements and transactional services.
Implemented secure local persistence for operational resilience.
Integrated with PAX smart POS hardware capabilities.
Applied mobile security best practices for enterprise deployment.
Engineering Decisions
The application was structured around Clean Architecture and MVVM to separate presentation, domain logic, data access, and external integrations. This made it easier to add new banking agreements without coupling each service directly to device, network, or UI concerns.
A native Android implementation with Kotlin and Jetpack Compose provided direct access to platform capabilities and PAX device integrations while keeping the user interface aligned with the operational constraints of dedicated smart POS terminals.
Application dependencies were managed with Hilt so repositories, services, persistence components, and hardware integrations could remain loosely coupled. This helped keep feature modules easier to test, evolve, and replace as the platform expanded.
Remote banking services were accessed through a dedicated networking layer built around Retrofit. API communication, authentication headers, error handling, and service responses were kept outside the presentation layer so transactional flows remained easier to reason about.
The application combined Room and DataStore to separate structured local data from lightweight application state and preferences. Local persistence was used selectively to support continuity without treating the device as the authoritative source for financial transaction state.
Interactions with PAX smart POS capabilities were isolated behind integration components using the PAX SDK. Keeping device-specific behavior outside core business logic reduced coupling between banking workflows and hardware implementation details.
Key Challenges
Designing a scalable mobile architecture capable of supporting multiple banking agreements.
Securing transactional communication across distributed field devices.
Handling hardware-level integrations with PAX smart POS devices.
Managing secure credential and token storage on deployed terminals.
Implementing runtime integrity protections for enterprise-grade mobile operations.
Security Considerations
Communication with backend banking services used TLS 1.3 together with Certificate Pinning to strengthen transport security and reduce exposure to unauthorized certificate interception on field-deployed devices.
Sensitive credentials and cryptographic material were handled through Android Keystore rather than being stored directly in application files or plain local preferences. This kept sensitive material inside Android-managed security boundaries.
The mobile application coordinated transactional workflows, but backend services remained responsible for validating and authorizing financial operations. Local device state was not treated as authoritative for completed banking transactions.
The application included runtime integrity protections intended to identify unsupported or potentially compromised execution environments before sensitive banking functionality was allowed to continue.
Local storage was limited to information required for application behavior and operational continuity. Sensitive values were handled separately from ordinary persisted state, reducing unnecessary exposure on devices deployed outside traditional branch environments.
PAX hardware operations were isolated from core banking logic so device APIs could not directly bypass application-level validation or service orchestration. Hardware access remained part of controlled application workflows.
Impact
Expanded BANPRO’s distributed banking service coverage across Nicaragua.
Enabled faster access to banking services through local commercial agents.
Improved operational efficiency for financial transactions outside traditional branches.
Strengthened security and operational reliability on field-deployed POS devices.
Established a scalable mobile foundation for future banking agreements and services.