Analysis: The Growing Role of Messaging Standards in Identity — RCS, SMS, and Beyond

Hook: Why your verification flows are about to get a wake-up call

If you still lean on SMS one-time codes for account recovery, credential delivery, or identity verification, 2026 is the year to revisit that decision. Mobile messaging is changing faster than many organizations realize: carriers, handset makers, and standards bodies are converging on end-to-end encrypted Rich Communication Services (RCS) and related messaging security like MLS. That shift promises fewer intercepted OTPs and richer credential delivery, but it also introduces new integration, privacy, and recovery trade-offs that credential issuers and platform teams must address now.

The short takeaway (what product and security teams must act on today)

• Audit all flows that use SMS for verification or certificate delivery and classify risks (low/medium/high).
• Plan multi-channel verification with RCS as primary where available and secure fallbacks (FIDO passkeys, email + device attestation).
• Embed cryptographic signing into credential delivery (signed VCs, JWS attachments) so messages remain verifiable outside the messaging channel.
• Update recovery policies to reduce reliance on any single carrier-dependent channel and add device-bound attestations.
• Test end-to-end workflows in target markets — RCS adoption, carrier toggles, and iOS behavior vary significantly by country and operator.

What changed in 2025–2026: a brief chronology

From late 2024 through 2026 the industry moved from speculation to early deployment:

• GSMA pushed Universal Profile 3.0 and formalized Message Layer Security (MLS) profiles tailored to RCS messaging.
• Android OEMs and major carriers implemented RCS clients with MLS support; interoperability tests matured across Europe and parts of Asia in 2025.
• Apple's iOS beta builds exposed code paths and carrier toggles for MLS-based RCS E2EE, signaling serious intent to support cross-platform encrypted RCS conversations.
• By early 2026, a growing number of operators had enabled MLS in limited markets, and vendors began offering RCS-enabled APIs aimed at verification and messaging platforms.

Why this matters for identity verification and credential delivery

RCS E2E and MLS materially change the threat model and capabilities of mobile messaging:

• Security upgrade. With MLS-based E2EE, passive interception vectors (SS7/SS7-like signaling attacks or on-path carrier servers) are reduced compared to SMS, which transits the network in plaintext.
• Richer messages. RCS supports structured attachments, suggested actions, and rich cards — enabling direct delivery of signed credential objects rather than SMS text links or codes.
• New metadata risks. Signaling and provisioning still expose metadata to carriers and networks; E2EE does not fully remove metadata leakage like recipient IDs, timestamps, or conversation participants.
• Heterogeneous adoption. RCS availability and behavior remain carrier- and OS-dependent. In markets where RCS E2E isn't enabled, SMS fallbacks persist.

For verification flows

OTP-by-SMS has long been a convenience that paid for itself with high user familiarity. RCS E2E reduces the risk of intercepted OTPs, but it also changes how verification can be performed:

• Shift from ephemeral numeric OTPs to signed tokens embedded in the message. These tokens can be JWS/JWT or CBOR Web Tokens (CWT) and include non-replayable claims (nonce, audience, expiry) and issuer signatures.
• Use RCS suggested actions to present one-tap verification buttons that trigger in-app flows or deep links bound to the device session — reducing manual code entry and account-takeover risk.
• Combine RCS with device-bound attestation (e.g., SafetyNet/Play Integrity on Android, Apple DeviceCheck, or FIDO attestation) to tether the verification to a public key controlled by the user's device or wallet.

For credential delivery

RCS enables a better delivery format for digital certificates and verifiable credentials (VCs):

• Deliver signed VCs as attachments (JSON-LD, JWT-VC, CBOR) with a cryptographic signature that can be verified independently of the messaging transport.
• Leverage RCS rich cards to show credential metadata immediately (issuer, expiry, scope) and a single tap to import into mobile wallets supporting W3C VCs or DIF protocols.
• Use DID-based pointers in the message (DID URLs) to initiate DIDComm exchanges for holder-to-verifier interactions rather than sending sensitive data directly in the message body.

New threats and residual risks to plan for

No technology is a magic bullet. RCS E2E reduces some risks but introduces or fails to fully eliminate others:

• SIM swap & number porting. An attacker who ports a number or performs an account takeover at the carrier can still receive RCS messages if the carrier’s provisioning process implicitly migrates the user's identity to a new device — so rely on multi-factor and device-bound proofs, not messaging alone.
• Account provisioning attacks. Carrier customer service social engineering remains a vector. Organizations should avoid recovery processes that can be completed solely through carrier callbacks or knowledge-based checks tied to a phone number.
• Metadata scraping. Even with E2EE, metadata about recipients and times may be accessible to carriers or MVNOs. This can be sensitive for high-risk credential holders or exam proctors.
• Fragmentation and fallback abuse. Attackers may exploit fallback to SMS where RCS E2E is not enabled; smart detection of channel capability and strict policy for fallback are essential.

Practical migration plan for credential issuers and verification SaaS

Below is a step-by-step migration plan you can adapt. It balances fast wins with long-term architectural changes that future-proof credential delivery and verification.

Phase 1 — Audit and fast mitigations (0–3 months)

1. Inventory all user flows relying on SMS: enrollment, OTP, password reset, certificate delivery, and administrative alerts.
2. Classify flows by impact and sensitivity (e.g., low: marketing OTPs; high: certificate issuance, account recovery).
3. Immediately stop using SMS as the sole recovery channel for high-risk accounts; add email + recovery codes or hardware-backed factors.
4. Begin signing any credential delivered over SMS/RCS with JWS so the message carries a verifiable artifact you can validate later.

Phase 2 — Pilot RCS-enabled verification (3–9 months)

1. Select target markets where RCS E2E adoption is high (usually parts of Europe, India, Southeast Asia as of early 2026) and run A/B pilots to measure conversion and security.
2. Use a messaging provider that exposes RCS attachments, suggested actions, and MLS status APIs so you can detect whether the recipient’s channel supports E2E.
3. Deliver signed credential objects and one-tap verification links that are cryptographically bound to the session or device public key.
4. Instrument detection of fallback to SMS and flag accounts that fall back more than N times for manual review.

Phase 3 — Architect for verifiable, transport-agnostic credentials (9–18 months)

1. Adopt W3C Verifiable Credentials for issued certificates; sign with issuer keys and publish revocation data to a reliable registry or ledger (permissioned or public depending on privacy needs).
2. Integrate DIDs for identity pointers and support DIDComm where possible to enable direct, encrypted holder–verifier exchanges without relying on the carrier as a transport.
3. Implement FIDO/WebAuthn or passkeys for authentication and account recovery flows, with messaging reserved for channel notifications rather than sole authorization.
4. Design wallet onboarding flows that let recipients import credentials directly from rich messages into their chosen wallet (Apple Wallet, Google Wallet, or third-party wallets supporting VCs).

Concrete design patterns and examples

Here are practical patterns you can start implementing today.

Pattern: Signed short-lived verification token in RCS

• Issuer generates a JWT/JWS containing: iss (issuer), aud (client app id), sub (user id), jti (nonce), iat, exp (short life, e.g., 90s).
• Issuer signs with its rotation-enabled key; message carries the token as an attachment and a suggested action button labeled “Confirm sign-in”.
• Button deep-links into the app with the token; server validates signature, audience, nonce, and device attestation before completing verification.

Pattern: VC delivery via RCS with offline verification

• Issue a W3C VC signed by the issuer (JWT-VC or JSON-LD), include a revocation pointer (CRL URL or revocation registry entry).
• Send the VC as an RCS attachment; show a rich card with issuer, credential type, and confidence level. Provide “Save to Wallet” action that writes the VC into the recipient’s secure wallet.
• Verifiers can request the VC from the holder and validate the signature and revocation status independent of the messaging channel.

Pattern: Account recovery without single-channel dependence

1. Require two independent signals for recovery: an out-of-band factor (e-mail or hardware token) and a device attestation plus knowledge of a backup recovery code stored offline.
2. When a phone number change is detected, trigger a high-friction flow: send RCS notification (if supported) and require verification through the app with FIDO2 attestation and an uploaded government ID check (if permitted by policy).

Market and policy considerations for 2026

Adoption will be uneven. Consider these geographic and regulatory filters:

• Europe: strong momentum for RCS E2E in 2025–2026 and clearer privacy regulations (GDPR) that shape what metadata you can persist.
• US: slower carrier coordination; Apple’s full platform support came later and many US operators remain conservative about enabling cross-platform MLS. Plan for longer SMS fallbacks.
• India, Southeast Asia: high RCS uptake driven by handset vendors and operator packs — good early markets for RCS-enabled credential pilots.
• Education and regulated credentials: check jurisdictional rules about delivering certificates via third-party channels; where required, prefer signed credentials and provable exchanges rather than relying on transport security alone.

Operational playbook for security teams

1. Maintain an operational list of carrier capabilities and toggles per market; integrate this with your messaging provider so you can route or modify flows in real time.
2. Log message delivery events but avoid logging sensitive message content; preserve only signed tokens or digest pointers for auditability.
3. Rotate issuer keys regularly and maintain revocation registries accessible to verifiers with low-latency checks.
4. Run red-team simulations of porting and provisioning attacks to validate recovery policies and fallback behaviors.

Case study: A university pilot (hypothetical, practical example)

Imagine a mid-sized university issuing microcredentials to continuing-education students. Their old flow emailed PDFs and used SMS OTP to validate new recipients. Risks: PDF tampering, SMS interception, and students losing certificates when phone numbers change.

What they did in a 6‑month pilot:

• Issued microcredentials as W3C VCs, signed with a campus PKI key and published revocation pointers to a permissioned ledger operated by the university consortium.
• Delivered credentials via RCS where supported with a “Save to Wallet” action; for non-RCS markets, delivered a secure deep link via email requiring FIDO authentication first.
• Added a recovery flow that required two signals (email + FIDO attestation) instead of SMS-only recovery.
• Result: 40% reduction in credential-support tickets, faster imports into wallets, and no observed credential fraud over the pilot period.

Future predictions (2026–2028): what to prepare for

• RCS E2E will be a dominant secure messaging channel in many international markets, but SMS will persist in lower-tier markets and as a fallback for the foreseeable future.
• Credential delivery will move from link-and-download patterns to direct VC import flows via messaging, increasing user conversion when combined with wallet integration.
• DID-based exchanges and DIDComm will reduce the need for carriers as intermediaries in high-assurance credential exchanges.
• Regulators will demand more transparency about metadata and cross-border signaling; credential issuers should prepare for audits of their message retention and recovery policies.

Actionable checklist — Immediate next steps (copyable)

• Inventory: Map every flow that uses SMS/RCS for auth or credential delivery.
• Prioritize: Mark flows by risk and exposure; focus on recovery and credential issuance first.
• Pilot: Choose one market with strong RCS E2E and run a credential delivery pilot using signed VCs.
• Architect: Add device-bound keys and FIDO to your primary auth stack; make messaging a secondary authorization signal.
• Governance: Update privacy and retention policies, and maintain an incident playbook for SIM swap and provisioning attacks.

"Messaging is not just a transport anymore — it's a credential UX. Treat it as part of your security architecture, not an afterthought."

Conclusion: A strategic opportunity masked as engineering work

RCS E2E and MLS are not merely box-ticking enhancements to mobile messaging. They reframe how credentials can be delivered, verified, and recovered — shifting value from fragile text codes to signed, transport-agnostic artifacts. That transition creates both opportunity (better UX, fewer intercepted tokens, richer wallet integrations) and responsibility (new privacy decisions, fallback risks, and operational complexity). For credential issuers, platform teams, and identity vendors, the next 12–24 months are about redesigning flows, embedding cryptography across delivery channels, and building recovery options that don’t depend on a single network operator.

Call to action

Ready to modernize your verification and credential delivery flows for the RCS era? Start with a free 30‑minute audit: we’ll map your SMS/RCS dependencies, recommend a phased migration plan, and prioritize where signed verifiable credentials and device binding will give you the biggest security and UX wins. Contact the team at certify.top or request a demo to get started.

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