> ## 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.

# Card Issuers

> Technical integration guide for card issuers implementing DRP to provide encrypted digital receipts to cardholders.

# Card Issuer Integration Guide

This guide covers the technical requirements and integration paths for card issuers implementing DRP.

***

### Integration Architecture

#### Three integration paths

**1. Full Native Integration** (recommended)

* Add DRP SDK to existing banking app
* Receipts appear in transaction history automatically
* Typical development timeline: 2-4 weeks for experienced mobile teams

**2. Hosted Solution**

* Drop-in receipt viewer component
* Handles encryption/decryption logic
* Faster integration: 1-2 weeks

**3. API-Only**

* Webhook receiver for encrypted receipts
* Build custom UI in your app
* Maximum flexibility for custom implementations

**All approaches maintain client-side encryption—private keys never touch issuer servers.**

***

### Security & Compliance

#### Cryptographic architecture

* RSA-2048 encryption with client-side key generation
* Hardware security module integration (iOS Secure Enclave, Android KeyStore)
* Private keys never leave user devices

#### Compliance considerations

* GDPR-compatible design (user controls all personal data)
* PCI-DSS compatible (receipt data outside cardholder data scope)
* Cryptographic audit trail for regulatory requirements

#### Fraud prevention features

* Dual signatures from merchant and issuer prevent receipt forgery
* Tamper-evident cryptographic seals
* Real-time verification of merchant legitimacy

***

### SDK Reference

#### Available SDKs

* Swift (iOS) - production-ready
* Kotlin (Android) - production-ready
* JavaScript - for web-based banking portals
* API specifications for backend integration

#### Developer resources

* Complete technical documentation
* Sandbox environment for testing
* Integration support

***

### Technical FAQ

<AccordionGroup>
  <Accordion title="How long does DRP integration take?">
    **Full native integration:** 2-4 weeks for experienced mobile development teams

    **Hosted solution:** 1-2 weeks with drop-in components

    **API-only:** Timeline varies based on custom UI requirements
  </Accordion>

  <Accordion title="Do we need to store or manage customer private keys?">
    No. Private keys are generated and stored exclusively on user devices in hardware security modules (iOS Secure Enclave, Android KeyStore). Your infrastructure never touches private keys.
  </Accordion>

  <Accordion title="How does DRP integrate with existing fraud detection systems?">
    DRP provides itemized transaction data and dual cryptographic signatures that can be incorporated into existing fraud models. The protocol includes merchant verification and tamper-evident seals.
  </Accordion>

  <Accordion title="How do we handle merchants who don't support DRP yet?">
    DRP degrades gracefully. Transactions at non-participating merchants continue normally—customers simply don't receive itemized receipts for those purchases.
  </Accordion>

  <Accordion title="Is DRP compliant with banking regulations and data privacy laws?">
    DRP is designed for compliance:

    * **GDPR:** User controls all personal data with client-side encryption
    * **PCI-DSS:** Receipt data falls outside cardholder data scope
    * **Banking regulations:** Cryptographic audit trails support regulatory requirements

    Consult your compliance team for jurisdiction-specific requirements.
  </Accordion>

  <Accordion title="What happens if a merchant goes out of business?">
    Receipts remain accessible to users indefinitely since they're stored client-side on user devices. The cryptographic signatures provide proof of purchase regardless of merchant status.
  </Accordion>
</AccordionGroup>