How to Use Encrypted RCS for PCI-Sensitive Customer Communications

Stop guessing: can you send payment info over RCS without failing PCI?

Merchants and ops leaders face a hard truth in 2026: customers expect modern, conversational payments (RCS, rich cards, quick-pay links), but payment teams can’t trade convenience for compliance. This guide explains whether and how you can send payment-related messages (masked card digits, payment tokens, one-click links) over end-to-end encrypted (E2EE) RCS while addressing PCI DSS obligations, practical engineering controls, and verification steps you must take before sending a single message.

The bottom line, up front

You can use E2EE RCS for payment-related customer communications — but only when you remove or tokenize cardholder data and verify real E2EE, key management, and provider contractual controls. Sending full PANs or any Sensitive Authentication Data (SAD) over RCS (or any messaging) will almost always put you squarely into PCI scope and likely violate PCI DSS requirements. Use tokenization, short-lived payment links, or processor-hosted Pay-By-Link workflows to keep your messaging systems out of sensitive scope.

What changed in 2024–2026: RCS + E2EE landscape

RCS messaging matured quickly after the GSMA’s Universal Profile 3.0 and the MLS-based E2EE specifications. By early 2026 most major Android clients (Google Messages, Samsung Messages) and an increasing number of carriers support MLS (Messaging Layer Security) for E2EE, and Apple’s incremental support for RCS E2EE expanded cross-platform encryption availability. But adoption is still heterogeneous — some carriers and app stacks do not enable E2EE by default, and business messaging routes (RCS Business Messaging, RBM) can involve intermediaries that break end-to-end guarantees unless explicitly supported.

Implication for merchants: do not assume RCS messages are end-to-end encrypted by default. You must validate the specific provider and route before treating any content as protected.

PCI DSS fundamentals that govern messaging

Before designing a solution, align on three PCI concepts:

• Cardholder Data (CHD) — includes the Primary Account Number (PAN). CHD must be protected in transit and at rest.
• Sensitive Authentication Data (SAD) — full track data, CAV2/CVC2/CVV2, PINs. SAD must never be stored post‑authorization and should not be transmitted via consumer messaging.
• Scope — any system that stores, processes, or transmits CHD or SAD is in PCI scope. Even touching PAN in an insecure system can expand compliance obligations.

PCI DSS v4.0 (and subsequent clarifications through 2025) emphasizes risk-based controls and documented validation of compensating controls. Messaging over new channels like RCS falls under the same transmission rules: encryption in transit is required, but encryption alone does not remove PCI obligations if CHD or SAD are present.

Which payment data you can — and cannot — send over RCS

Here’s a practical, risk-based matrix to guide messaging design.

Lower-risk / Acceptable with controls

• Masked PAN (e.g., "**** **** **** 1234") — permitted; does not constitute full PAN and generally does not expand PCI scope when no reversible PAN is exposed. Still treat carefully (minimize retention, avoid logging).
• Payment tokens (non-reversible) — preferred. Tokens issued by your payment processor (or via EMVCo/PCI-approved tokenization) that cannot be used elsewhere are acceptable when the tokenization provider remains PCI compliant.
• One-time or short-lived payment links — recommended. Links that redirect customers to a PCI-compliant payment page (hosted by a PSP) keep your messaging system out of CHD scope.
• Transaction confirmations with last4 and amount — fine, provided no SAD, no full PAN, and logs don’t store CHD.

High-risk / Prohibited

• Full PAN in cleartext — do not send over RCS or any messaging channel unless you are an extensively validated PCI environment and have a specific business justification and controls — rare for consumer messaging.
• SAD (CVV, PIN, track data) — never transmit via RCS.
• Reversible tokens or shared PAN fragments that can be reassembled — treat as PAN and avoid.

Practical implementation checklist: step-by-step

Use this checklist when you plan to send payment-related messages over RCS.

1. Map data flows. Document where messages are composed, stored, transmitted, and rendered on devices. Identify whether any system touches PAN or SAD.
2. Choose tokenization-first design. Prefer processor-issued tokens or vault references. Never embed PANs in the message. Example: send token TKN-58ab… plus a PCI-hosted pay link.
3. Verify E2EE on the exact messaging route. Ask providers for MLS compliance documentation, key management details, and whether business channels preserve end-to-end properties. If a business RCS aggregator terminates encryption for message personalization, assume no E2EE.
4. Use short-lived, single-use payment links. Links should expire quickly (recommend 10–60 minutes depending on risk), be single use, and require POS-authentication or 3DS when appropriate. See guidance on redirect safety when building link flows.
5. Disable message logging of sensitive fields. Ensure your messaging platform and any intermediaries do not log tokens, masked digits beyond last4, or payment links in clear text. Tie observability and privacy controls together — see approaches for observability & privacy workflows.
6. Contractual and audit controls. Require SOC2/ISO27001 and PCI evidence from vendors. Include breach notification, data handling obligations, and right-to-audit clauses.
7. Retention and DLP. Apply data-loss prevention rules to drop or mask payment-related content in backups, analytics, and monitoring systems.
8. Legal and privacy compliance. Update privacy notices and consent flows, ensure opt-in/opt-out messaging controls, and conform to GDPR/CPRA practices for messaging preferences. Privacy-first observability approaches such as those used in modern calendar/ops tooling can be instructive.
9. Consult a QSA. Before launch, validate design with a PCI QSA; document compensating controls if you deviate.

Example: secure RCS pay flow (recommended)

This is a minimal, PCI-friendly flow that preserves user experience while reducing scope.

1. Customer opts in to RCS communication and registers a device ID.
2. Your backend requests a single-use payment token / link from your PSP for the specified amount and customer reference. The PSP returns a one-time token TTL=15m and a hosted payment URL (hosted on PSP domain).
3. Your system composes an RCS message containing: merchant branding, masked last4, amount, and the one-time URL (no PAN, no CVV, no reversible data).
4. Message is sent via an RCS Business Messaging provider that preserves E2EE for that route (provider attests to MLS usage) or, if not E2EE, you fall back to a non-CHD message or SMS with a lighter call-to-action.
5. Customer taps link and completes payment on the PSP’s PCI-compliant page.

Benefits: CHD never transits or resides in your messaging system; PSP handles capture and storage; your scope is minimized.

Sample pseudocode (conceptual)

Below is a high-level pseudo-example of how your backend could request a one-time link and send an RCS message. This is not production code — it illustrates the sequence.

    // 1. Request one-time pay link from PSP
    response = PSP.createOneTimeLink(amount, currency, customerId, expiresIn=900)
    link = response.url      // hosted on PSP domain
    tokenRef = response.ref  // non-reversible token

    // 2. Compose RCS content
    rcsMessage = {
      title: "Pay $amount for Order #1234",
      body: "Tap to pay with card ending in 1234. Link expires in 15 minutes.",
      cta: {label: "Pay now", url: link}
    }

    // 3. Send via RCS provider
    RCSProvider.send(to=deviceRcsAddress, message=rcsMessage)
  

How to confirm an RCS implementation is truly E2EE

Vendors sometimes use the term "encrypted" loosely. Use this checklist to validate E2EE:

• MLS compliance — provider supports Messaging Layer Security and can provide implementation details.
• End-to-end key control — keys are generated and managed on client devices or in a service that does NOT terminate encryption at an aggregator. Verify whether aggregator-side personalization breaks E2EE.
• Forward secrecy — the channel should provide perfect forward secrecy so past messages cannot be decrypted if a key is compromised.
• Attestation and transparency — request cryptographic attestation or a whitebox of the client app’s encryption behavior; check for third-party audits (e.g., NCC Group, independent crypto review).
• Fallback behavior — define how messages degrade if E2EE is unavailable (e.g., don’t send payment links if route is not E2EE-enabled; instead queue or switch channels). See incident responder guidance for fallback and notification patterns.

Scope reduction techniques and relevant SAQs

Proper design can reduce your PCI scope:

• Use processor-hosted payment pages or tokenization — if you never handle PANs, you may qualify for SAQ A or A-EP depending on where the redirect originates. Messaging channels that include only links and masked last4 are favorable for scope reduction.
• Isolate messaging systems — separate the messaging platform from systems that store PANs, with clear network segmentation, unique credentials, and minimal ACLs.
• Document compensating controls — if a business need forces you to send sensitive data (rare), prepare compensating controls and QSA review; expect higher compliance effort.

Note: SAQ applicability varies by architecture and region; always consult a qualified QSA to confirm which SAQ or Report on Compliance applies.

Incident scenarios and response planning

Create an incident response playbook specific to messaging channels:

• Identify who to notify (PSP, RCS provider, carriers, QSA).
• Revoke active tokens/links immediately and rotate any affected keys.
• Assess scope of exposed data — if only masked digits were in messages and tokens were used, impact could be limited.
• Preserve evidence and engage forensic specialists experienced with messaging platforms and mobile app attestations. See recent incident postmortems for responder playbooks.

Advanced strategies and future-proofing (2026+)

As we move through 2026, here are advanced techniques and industry trends to adopt:

• Federated tokenization — shared token formats that let merchants reference a token without hosting it locally, reducing PCI footprint. See research on authorization patterns beyond tokens.
• Push-to-pay standards — EMVCo and industry push-to-pay integrations allow one-tap card-on-file pay flows via messaging with better security posture.
• Hardware-backed keys and device attestation — leverage platform attestation (Android Keystore, Secure Enclave) to bind identities and verify device-side E2EE. On-device and edge personalization patterns show how attestation improves trust.
• Minimal metadata — in 2026, privacy-conscious designs minimize telemetry that can correlate payments to identities; strip or hash unnecessary metadata before storing.
• Continuous verification — request regular third-party audits and cryptographic attestation snapshots from RCS providers rather than once-off statements.

“Encryption alone doesn’t equal compliance. The key question is who controls the keys and whether any system in the message path can access PAN or SAD.”

Common pitfalls — and how to avoid them

• Assuming all RCS = E2EE. Verify route-specific encryption. If the provider performs server-side content enrichment, E2EE may be broken.
• Embedding payment credentials in URLs. Never place PAN or CVV in query parameters; if links must contain identifiers, use non-reversible tokens and short TTLs. See guidance on redirect safety.
• Logging sensitive message content. Check all logs, analytics, monitoring, and backups for inadvertent CHD capture and implement DLP rules and privacy-aware observability.
• Overlooking fallback channels. If E2EE is unavailable and your fallback is SMS, treat the fallback as a less-secure channel and avoid sending anything sensitive.

Checklist before you launch

• Do a full data flow diagram and threat model.
• Confirm E2EE and MLS compliance with provider — get documentation.
• Use processor-issued tokens or PSP-hosted payment links only — no PAN in messages.
• Implement DLP and retention rules — purge messages and logs as appropriate.
• Update privacy notices and obtain opt-in for payment messaging.
• Validate with a QSA and keep evidence of vendor audits.
• Test incident response on a messaging breach scenario.

Final takeaways — what ops leaders and merchants must remember

Encrypted RCS unlocks excellent customer experiences in 2026 — but encryption is only one piece of the compliance puzzle. To use RCS for payment-related communications safely:

• Never send full PAN or SAD via messaging.
• Prefer tokens and one-time PSP-hosted links.
• Verify end-to-end encryption and key control on your exact route.
• Lock down logging, retention, and DLP so message content doesn’t create extra PCI scope.
• Engage a QSA before launch to formalize scope and controls.

Next steps (call to action)

If you’re evaluating RCS payments, don’t launch on assumptions. Contact our security and engineering team at ollopay to:

• Review your message flows and PCI scope impact;
• Validate RCS provider E2EE/MLS claims and key management;
• Design token-first pay flows and short-lived links that keep you out of CHD scope.

Ready for a risk-free RCS payments pilot? Schedule a technical review with our payments architects — we’ll map your flows, recommend tokenization patterns, and help you document the controls your QSA needs.

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