Digital Payments & E-Payment Systems: Models, Tech & Security

Key Concepts in Digital Payments

Digital payments enable secure, electronic transactions replacing cash or checks. They include:

• Prepaid cards (e.g., stored-value cards)
• Credit/debit cards (e.g., Visa, Mastercard)
• Digital wallets (e.g., eSewa, Khalti)
• Mobile payments (e.g., UPI in India, Ncell’s mobile money)
• Cryptocurrencies (e.g., Bitcoin, stablecoins like USDC)

1. Types of Digital Payment Systems

Digital payments are classified based on transaction flow, security, and medium:

flowchart TD
  A["Digital Payment Systems"] --> B["Prepaid Cards"]
  A --> C["Credit/Debit Cards"]
  A --> D["Digital Wallets"]
  A --> E["Mobile Payments"]
  A --> F["Cryptocurrencies"]
  A --> G["E-Checks"]
  A --> H["Bank Transfers"]
  B -->|"Example: eSewa"| I["Digital Wallet"]
  E -->|"Example: IME Pay"| J["Mobile Payment"]
  F -->|"Example: Bitcoin"| K["Cryptocurrency"]

Key Definitions:

• Prepaid Card: Loaded with funds (e.g., Ncell’s recharge card).
• Credit Card: Borrowed funds (e.g., Visa Classic).
• Digital Wallet: Virtual storage for payment methods (e.g., eSewa).
• Mobile Payment: Transaction via smartphone (e.g., Pathao’s in-app payments).
• Cryptocurrency: Decentralized digital currency (e.g., Bitcoin).

2. How Digital Payments Work: A Worked Example

Scenario: Buying a Daraz order via eSewa.

1. User selects eSewa in Daraz’s checkout.
2. eSewa app opens → user logs in.
3. OTP verification sent to phone.
4. Payment deducted from user’s eSewa balance.
5. Confirmation email/SMS sent to buyer and seller.

Visual Flow:

sequenceDiagram
    participant User
    participant Daraz
    participant eSewa
    participant Bank

    User->>Daraz: Selects eSewa
    Daraz->>eSewa: Request payment
    eSewa->>User: Request OTP
    User->>eSewa: Enters OTP
    eSewa->>Bank: Debit user account
    Bank-->>eSewa: Confirmation
    eSewa-->>Daraz: Payment successful

3. Comparison of Digital Payment Methods

4. Electronic Payment Systems (E-Payment)

E-payment systems automate transactions via:

• Credit Card Networks (Visa, Mastercard)
• Digital Wallets (eSewa, PayPal)
• Bank Transfers (Nepal Bank’s NEFT)
• Cryptocurrencies (Bitcoin, Ethereum)

How Online Credit Card Transactions Work:

1. User submits payment via website (e.g., Daraz).
2. Merchant sends request to Payment Gateway (e.g., Stripe).
3. Gateway forwards to Acquiring Bank (e.g., Global IME).
4. Issuing Bank (user’s bank) checks funds.
5. Authorization granted → transaction proceeds.
6. Capture: Merchant marks sale as complete.

Visual:

flowchart TD
    A["User"] -->|"1. Submits Payment"| B["Merchant"]
    B -->|"2. Request to Gateway"| C["Payment Gateway"]
    C -->|"3. Forward to Acquirer"| D["Acquiring Bank"]
    D -->|"4. Check with Issuer"| E["Issuing Bank"]
    E -->|"5. Approve/Reject"| D
    D -->|"6. Authorization"| C
    C -->|"7. Capture"| B

5. Digital Wallets: How They Work

A digital wallet stores payment details securely (e.g., eSewa, Khalti). Key Operations:

• Payment Authorization: Verifies funds before transaction.
• Payment Capture: Finalizes the transaction.

Example: Paying for a Pathao ride via Khalti.

1. User opens Khalti app → selects Pathao.
2. Authorization: Khalti checks balance.
3. Capture: Funds deducted; ride confirmed.

Security Features:

• Two-Factor Authentication (2FA): OTP/SMS.
• Encryption: PCI-DSS compliance.
• Tokenization: Replaces card numbers with tokens.

6. Security in Digital Payments

Threats:

• Fraud: Stolen card details (e.g., phishing).
• Hacking: Database breaches (e.g., 2017 Equifax leak).
• Malware: Keyloggers capturing credentials.

Solutions:

• SET Protocol: Secure Electronic Transaction (used in credit cards).
• PCI-DSS: Payment Card Industry Data Security Standard.
• Tokenization: Replaces sensitive data with non-sensitive tokens.

Example: SET Protocol Workflow (for credit cards):

1. User selects card → Merchant sends encrypted request.
2. Payment Gateway verifies with Issuing Bank.
3. Authorization sent back → Capture completes sale.

sequenceDiagram
    participant User
    participant Merchant
    participant Gateway
    participant Bank

    User->>Merchant: Selects card
    Merchant->>Gateway: Encrypted request (SET)
    Gateway->>Bank: Verify funds
    Bank-->>Gateway: Approve
    Gateway-->>Merchant: Authorization
    Merchant->>Gateway: Capture payment

7. Digital Payment Systems in Nepal

Real-World Example:

• eSewa’s Cashback Rewards: Users earn points for payments (e.g., 1% cashback on Daraz).
• Pathao’s Mobile Payments: Riders pay via Ncell Money without cash.

8. Challenges in Digital Payments

• Fraud: Fake websites (e.g., cloned Daraz pages).
• Regulation: Nepal’s Electronic Transaction Act (2064) mandates digital signatures.
• Infrastructure: Rural areas lack internet/ATMs.

Solutions:

• Biometric Authentication (e.g., Ncell’s fingerprint login).
• Blockchain for Transparency (e.g., NEPSE’s digital ledger).
• Government Initiatives (e.g., Nepal Rastra Bank’s digital payment push).

In the Real World

1. eSewa’s Integration with Daraz:

   • Idea Used: Digital Wallet + One-Click Payments
   • How: Daraz’s checkout redirects to eSewa’s app for instant authorization. Users don’t need to enter card details repeatedly.
   • Worked Example: A user buys a ₹5,000 laptop on Daraz. Instead of filling in card details, they tap "Pay with eSewa," enter OTP, and the payment completes in 3 seconds.

2. Khalti’s Role in Pathao:

   • Idea Used: Mobile Payment + Tokenization
   • How: Pathao’s app uses Khalti to process payments without storing card numbers. The tokenized payment ID is sent to Khalti’s servers for verification.
   • Worked Example: A rider hails a Pathao cab in Kathmandu. The driver’s app shows the rider’s Khalti token, and the fare is deducted instantly from the rider’s linked bank account.

3. Ncell Money for Airtime Recharges:

   • Idea Used: Stored-Value Payment System
   • How: Ncell Money acts as a prepaid wallet where users load funds (via bank transfer or cash deposit) and use them to recharge airtime or pay bills.
   • Worked Example: A student in Pokhara loads ₹1,000 into their Ncell Money wallet via an ATM. They then use this balance to recharge their Ncell SIM for ₹200, leaving ₹800 in their wallet.

Exam Tip

• Focus on Workflows: Exams often ask how a system like SET Protocol or credit card transactions work. Draw a sequence diagram (like above) to show steps clearly.
• Compare Methods: Always include a table (like the one on payment methods) to highlight pros/cons.
• Real-World Tie-Ins: Link concepts to Nepal’s systems (eSewa, Khalti) or global ones (PayPal, UPI). Example:

  "Unlike PayPal’s global reach, eSewa is optimized for Nepal’s low internet penetration by supporting offline OTP verification."

• Security is Key: Mention PCI-DSS, tokenization, or SET Protocol when discussing fraud prevention.
• Act Now: Practice tracing a Daraz checkout or Pathao ride payment step-by-step—this is a common exam question.