Blockchain from scratch in Go with gRPC

• Guided blockchain from scratch in Go https://github.com/volodymyrprokopyuk/go-blockchain
• Designed, implemented, tested, and documented a complete blockchain from scratch in Go using gRPC as the inter-node communication protocol. The blockchain manages accounts using the Secp256k1 elliptic curve key pairs and the AES-GCM encryption with the Argon2 KDF. The blockchain verifies transactions and creates blocks using the ECDSA Secp256k1 digital signatures and the Keccak256 hash function. The blockchain employs the Merkle proof to prove the inclusion of transactions into blocks, and verify the integrity of transactions on the blockchain. The blockchain implements the concurrency safe peer discovery mechanism in the peer-to-peer blockchain network. The concurrency safe transaction relay and the block relay mechanisms ensure the resilient propagation of transactions through the peer-to-peer network, and the synchronization of the blockchain state on each node using the Go channel composition and multiplexing, and the gRPC server and client streaming. The blockchain state manages the lifecycle of transactions and blocks in the concurrency safe way using the Go mutexes and channels. The blockchain implements the Proof of Authority consensus. The concurrency safe blockchain node event streaming concurrently delivers blockchain domain events in real-time to subscribed clients using the Go concurrency primitives and the gRPC server streaming. The blockchain provides the CLI over the gRPC to have complete control of the blockchain from the command line. The 140-page guide fully documents the blockchain design and implementation. The guide explains the theoretical foundations, and provides the practical testing and usage examples, invaluable for effective learning of the blockchain concepts, and progressive building of the blockchain from scratch in Go

Federated IAM for instant payment processing

• Situation: an instant payments product provides reliable and efficient connectors to different payment schemes along with a unified payment data store that is the single source of truth for all payment processing. Before the change: all access to the payment connectors and the payment data store was managed through manually provisioned generic accounts reused by client bank operators and bank systems
• Task: design and implement a federated IAM solution that securely manages access of client bank operators and bank systems to applications and APIs of the instant payments product. The IAM solution should support federated identity management and provide fine-grained access control mechanisms with corresponding security monitoring and access audit functions for client bank administrators
• Action: a standard-compliant, reliable, and scalable IAM solution delegates the initial authentication of principals to the bank federated identity provider, as well as supports the adaptive authentication with MFA by requesting additional authentication factors before granting access to sensitive payment information and critical operations. The IAM solution features dynamic, flexible, and fine-grained PBAC fully managed by client bank administrators
• Result: the standard-compliant IAM solution provides secure and compliant access of client bank operators and bank systems to the instant payment product applications and APIs. The IAM solution directly contributes to faster time-to-value, reduced operational costs, and increased customer trust by seamless integration with the bank-managed federated identity provider, and dynamic and flexible access policies fully controlled by the client bank administrators

Unified payment data store

• Situation: an instant payments product connects to multiple payment schemes e. g. SEPA, STEP1, STEP2, RT1, TIPS. Before the change: each payment scheme had its own scheme-specific payment processing view (operational dashboard). A payment operator had to consult multiple systems during a payment investigation or a manual payment repair
• Task: provide a unified view on payment processing under different payment schemes, allow enrichment of standard payment messages with customer-specific data while being compliant with ISO 20022
• Action: design and implement a generic relational data model that allows arbitrary typed connections between standard payment messages including non-standard customer-specific data payloads
• Result: increased customer satisfaction with the unified view on payment processing across multiple payment schemes, the scalable system-wide transaction log, the single source of truth for payment operations, real-time payment monitoring, and payment analytics

Stable FX pricing and execution

• Situation: a cross-border payment service provides very competitive real-time FX rates available to a big bank. However, FX rates are quite volatile and change frequently. Before the change: a real-time FX rate was provided for an initial quote, then an updated real-time FX rate was silently applied to the instructed payment which was totally unexpected to customers. This quickly transformed into a negative feedback and an increased abandonment rate
• Task: offer stable FX pricing to customers for the duration (15 mins) of their payment journey from the initial quoting and payment funding through the beneficiary screening and risk assessment to the payment routing and payment execution. The company absorbed the FX loss or gain due to the volatility of FX pricing
• Action: design and implement a stable FX pricing for 15 mins with an explicit notification of a customer about a new FX quote after 15 mins if a payment was not yet instructed
• Result: increased customer satisfaction and higher usage of the payment service due to elimination of unexpected changes of FX pricing during a payment journey

Automated digital identity verification

• Situation: a cross-border payment service provides payment services to a big number of customers in multiple countries (UK, Spain, Belgium). Before the change: a semi-manual process for customer onboarding with manual validation of every new customer. A customer onboarding was finished and the account activated only after a manual check that took 1-2 days. Periodic check of expired customer documents was not feasible for manual processing given a big number of customers
• Task: design a seamless and fully automated customer onboarding, automatically collect and verify customer personal data, enough to support AML and fraud checks from the KYC perspective. Automatically build a customer riks profile and calculate a customer risk score. Ensure seamless periodic checks of expired customer documents to stay compliant with regulations
• Action: design and implement integrations with country-specific providers of digital identity verification (capture of a national ID or a driver license, matching a selfie with the ID card, a liveness probe) to support a fully automated instant onboarding of low risk customer profiles
• Result: increased a lead-to-customer conversion, increased customer satisfaction, decreased abandonment rate due to a frictionless fully automated instant customer onboarding through a digital identity verification, as well as periodic checks of expired customer documents customer personal data

Senior Payments Architect

Worked as a Senior Payments Architect on the next generation instant payments framework IPF for Icon Solutions, the leading global provider of instant payments technology and mission-critical banking solutions for tier 1 global banks and payment service providers worldwide

Cross-border Payments Platform Architect

Worked as a Cross-border Payments Platform Architect on the next generation cross-border payments and foreign exchange platform PagoFX for Santander, the multinational commercial bank and financial services company

Team Lead, Security Architect

Worked as a Team Lead and a Security Architect on the content protection anti-piracy response platform Armada for NAGRA, the global leader in digital security, conditional access, and convergent media solutions

Solution Architect

Worked as a Solution Architect for the leading Spanish IT consultancy

Solution Architect

Worked as a Solution Architect on the full digital transformation of the credit card business core system for Diners Club Spain, the charge and credit card international company

Solution Architect

Worked as a Solution Architect for the leading international IT consultancy

Technical Lead

Worked as a Technical Lead on the next generation Salesforce CRM intelligent integration for Iberia, the flag carrier airline of Spain

Frontend Architect

Worked as a Frontend Architect for the leading Spanish IT consultancy

Frontend Quality Architect

Worked as a Frontend Quality Architect on the next generation global banking mobile application for BBVA, the international Spanish banking group

Senior Software Engineer

Worked as a Senior Software Engineer on global flight reservation services and travel agency back office business applications for Amadeus, the major international IT provider for the global travel and tourism industry

Master of Business Administration, MBA

Master of Informatics Engineering, MSc

Master of Science in Computing Systems, MSc

Bachelor of Science in Computer Science, BSc

Oxford Cyber Security for Business Leaders

Blockchains, Cryptocurrencies, Smart Contracts, and Ethereum