> ## Documentation Index
> Fetch the complete documentation index at: https://docs.digitalreceiptprotocol.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Merchants

> Technical integration guide for merchants implementing DRP to send cryptographically signed digital receipts.

# Merchant Integration Guide

This guide covers how merchants integrate with DRP to send encrypted, itemized receipts to customers.

***

### How DRP Works for Merchants

#### Transaction Flow

1. Transaction completes as normal through your POS
2. POS system generates itemized receipt in JSON-LD format
3. Your private key signs the receipt cryptographically
4. Receipt encrypted with customer's public key (provided by issuer)
5. Transmitted to customer's bank

**No changes to checkout flow. Receipt transmission happens asynchronously after payment authorization.**

***

### Integration Options

#### POS System Plugins (simplest)

If you use Square, Toast, Shopify, or other major POS platforms, install the DRP plugin from their marketplace. Setup takes 15-30 minutes.

#### Direct API Integration

For custom POS systems, integrate DRP API directly. Open-source libraries available in:

* JavaScript/Node.js
* Python
* Go
* PHP

#### Payment Processor Integration

As payment processors adopt DRP, receipts can route through existing payment infrastructure with minimal merchant configuration.

***

### Implementation Steps

**Step 1: Register merchant keys**
Generate public/private key pair, register public key with participating issuers

**Step 2: Add receipt generation**
Create itemized JSON-LD receipts from existing transaction data

**Step 3: Sign and encrypt**
Use DRP library to sign with your private key, encrypt with customer public key

**Step 4: Transmit**
Send to issuer via webhook or payment processor

Complete documentation and code samples available in the developer portal.

***

### Data Privacy & Security

#### Merchant data

* Receipt content comes from your existing transaction records
* No third-party platforms access your sales data
* Cryptographic signing prevents receipt tampering

#### Customer privacy

Receipts are encrypted before transmission—merchants cannot read receipts after they're sent (by design). This protects customer privacy while giving them data ownership.

***

### Technical FAQ

<AccordionGroup>
  <Accordion title="What does DRP integration cost?">
    DRP is free and open-source. There are:

    * No transaction fees
    * No licensing costs
    * No ongoing platform charges

    The only investment is development time for integration.
  </Accordion>

  <Accordion title="Does DRP slow down checkout?">
    No. Receipt generation, signing, and encryption happen asynchronously after payment authorization. The DRP process adds less than 100ms to post-transaction processing with no impact on customer experience.
  </Accordion>

  <Accordion title="What if my POS system isn't supported?">
    You have three options:

    1. **Direct API integration:** Use open-source libraries (JavaScript, Python, Go, PHP) to integrate with any custom POS
    2. **Request POS provider support:** Contact your POS provider and request DRP integration
    3. **Payment processor integration:** As processors adopt DRP, it will work automatically through existing payment infrastructure
  </Accordion>

  <Accordion title="Do I need to change my receipt format?">
    No. DRP converts your existing itemized transaction data into JSON-LD format. If your POS already generates itemized receipts (most do), DRP uses that data.
  </Accordion>

  <Accordion title="How do I handle returns if receipts are encrypted?">
    Customer presents the receipt from their banking app (they decrypt it client-side). You verify the cryptographic signature to confirm authenticity.
  </Accordion>

  <Accordion title="Can customers opt out of DRP receipts?">
    Yes. DRP is opt-in at the issuer level—only customers whose banks have integrated DRP receive encrypted receipts. Customers who prefer email or paper receipts continue receiving them as before.
  </Accordion>

  <Accordion title="What data privacy obligations do I have with DRP?">
    Minimal. Since receipts are encrypted before transmission and you cannot decrypt them after sending, you have no ongoing data custody obligations for DRP receipts.
  </Accordion>

  <Accordion title="How does DRP prevent receipt forgery?">
    Every receipt includes your cryptographic signature. Any tampering breaks the signature, making forgery immediately detectable. Combined with issuer signatures, DRP provides strong fraud protection.
  </Accordion>
</AccordionGroup>