SECURITY AUDIT - ENCRYPTED MESSAGING 2025-2026

Canal Telegram - Chat Privacy & Cyber

Groupe SimpleX - Alternative privacy-first of Telegram

Date: January 11, 2026
Scope: 7 Messengers (Signal, Element, SimpleX, Session, Telegram, Olvid, XMPP)
Methodology: Technical analysis, public audits, CVE databases, architecture, jurisdiction


EXECUTIVE SUMMARY

App Score Verdict
SimpleX 92/100 ✓ Best absolute anonymity + PQKE
Olvid 87/100 ✓ Best for France + ANSSI certified
Signal 85/100 ✓ Gold standard, limited decentralization
Element 78/100 ✓ Good federation, open-source
Session 76/100 ⚠ Improving (PFS 2025), Sybil risk
XMPP 74/100 ⚠ Robust protocol, client-dependent
Telegram 42/100 ✗ NOT recommended (weak MTProto, Kremlin)

1. ENCRYPTION & CRYPTOGRAPHY

Signal

  • Protocol: Signal Protocol (Double Ratchet, X3DH, Curve25519)
  • E2EE: ✓ Default all messages
  • Forward Secrecy (PFS): ✓ Yes (per-message key rotation)
  • Post-Quantum: ✗ No (on roadmap)
  • Vulnerabilities: None critical (audits 2016-2024 validated protocol)
  • Verdict: A+ (industry standard)

Element/Matrix

  • Protocol: Olm/Megolm (Double Ratchet)
  • E2EE: ✓ Optional per room (default enabled)
  • Forward Secrecy: ✓ Yes (1:1 Olm, group Megolm with limitations)
  • Megolm weakness: Group history decryptable if session compromised (NCC audit 2016)
  • Post-Quantum: In development (MLS protocol)
  • Verdict: A- (good but group chat limitations identified)

SimpleX

  • Protocol: SMP + X3DH + Double Ratchet + PQKE (continuous)
  • E2EE: ✓ Yes + metadata encrypted
  • Forward Secrecy: ✓ Double-layer (outer + inner encryption)
  • Post-Quantum: ✓ ML-KEM continuous (regular key exchange)
  • Vulnerabilities: 2 medium (X3DH implementation, 2022 Trail of Bits) - fixed
  • Verdict: A+ (advanced, PQKE today)

Session

  • Protocol: Session Protocol (modified Signal initially)
  • E2EE: ✓ Yes
  • Forward Secrecy: ✗ ABSENT until v2 (2025 release now live)
  • Post-Quantum: ✓ ML-KEM implemented (2025)
  • Critical issue: PFS removed 2021, now restored in v2 Protocol
  • Verdict: B (PFS issue resolved, new protocol active)

Telegram

  • Protocol: MTProto 2.0 (proprietary, bespoke)
  • E2EE: ✗ Not default (optional "secret chats" only)
  • Server encryption: ✓ TLS client-server (NOT E2EE)
  • Vulnerabilities: 4 discovered (Royal Holloway/ETH Zurich 2016-2024)
    • Message alteration (trivial)
    • Plaintext recovery (medium, millions of messages required)
    • MITM attack possible (rare, extremely difficult)
  • Verdict: C (proprietary, flaws documented, E2EE optional)

Olvid

  • Protocol: Proprietary (AES-256 + HMAC-SHA-256)
  • E2EE: ✓ Yes default + metadata
  • Forward Secrecy: ✓ Yes (temporary keys per message)
  • Post-Quantum: ✗ No (but ANSSI researching)
  • Audits: ANSSI CSPN certified 2x (2021, 2024) - no exploitable vulnerabilities
  • Verdict: A (French government certified, proven architecture)

XMPP + OMEMO

  • Protocol: OMEMO XEP-0384 (Double Ratchet, X3DH)
  • E2EE: ✓ Optional (client-dependent)
  • Forward Secrecy: ✓ Weak (spec: only when both parties online)
  • Vulnerabilities: None critical (2015-2016 protocol stable)
  • Verdict: A (solid protocol, implementation variable)

2. METADATA & PRIVACY

Collection Overview

App IP logging Timestamps Social graph Contacts Notes
Signal Partial (calls) ✓ Server logs ✗ Yes (phone required) ✓ E2EE client Sealed Sender hides sender
Element ✓ Server logs ✓ Yes ✗ Yes (JID visible) ✓ E2EE client Federation = potential leak
SimpleX ✓ Queue rotation ✗ Minimal ✓ NONE (no global ID) ✓ E2EE client Best social graph protection
Session Partial (onion routing) ✓ Yes ✓ Random ID partial ✓ E2EE client Service Nodes know prev/next IPs
Telegram ✓ All IPs collected ✓ All ✗ Fully centralized ✓ Not E2EE SORM Russia access possible
Olvid ✓ Rotation P2P ✗ Minimal ✓ No global ID ✓ E2EE Hybrid P2P optimal
XMPP ✓ Server logs ✓ Yes ✗ JID visible ✓ E2EE client Depends on server operator

3. IDENTIFIERS & ANONYMITY

Signal

  • Required: Phone number (mandatory, no alternative)
  • Deanonymization: Yes (number = identifier)
  • Risk: Social graph exposed, problematic for activists
  • Mitigation: Burner SIM, Tor VPN (theoretical)

Element

  • Required: No (username@server)
  • Deanonymization: No (JID can be anonymous)
  • Risk: Server = centralized point
  • Mitigation: Self-host Matrix server

SimpleX

  • Required: NONE
  • Deanonymization: ✓ None (no global ID)
  • Feature: Incognito mode = different ID per contact
  • Uniqueness: Only messenger with zero identifiers design

Session

  • Required: Random 66-char Account ID (no phone)
  • Deanonymization: No (unless ID shared)
  • Sybil risk: Service Nodes stake-based (15k Oxen minimum)

Telegram

  • Required: Phone number + @username
  • Deanonymization: ✓ Yes (dual identifier)
  • Risk: Complete social graph exposed, SORM Russia access

Olvid

  • Required: No identifier (invitation-based)
  • Deanonymization: No (optional personal ID)
  • Architecture: Hybrid P2P = no centralized graph

XMPP

  • Required: JID (username@server)
  • Deanonymization: Depends on server (anonymous possible)
  • Variability: Each implementation different

4. ARCHITECTURE & DECENTRALIZATION

App Type Servers Control Self-host
Signal Centralized 1 entity (Signal Foundation) Single ⚠ Possible but complex
Element Federated Multiple (Matrix servers) Community ✓ Easy (Synapse)
SimpleX Decentralized 4+ relays per chat User ✓ SMP servers
Session Decentralized 2100+ Service Nodes Stake-based ⚠ Crypto-dependent
Telegram Centralized Telegram Inc + DATAIX/GlobalNet Kremlin risk ✗ Impossible
Olvid Hybrid P2P Proprietary relays Olvid Ltd ⚠ No
XMPP Federated Community servers Multi-admin ✓ Yes

Decentralization risks:

  • Session: Sybil attacks (staking mitigates but risk exists)
  • Element: Federation = trust multiple servers
  • SimpleX: 4 servers per conversation = potential correlation

5. OPEN SOURCE & AUDITS

Signal

  • Code: ✓ Open-source (client + server + libsignal)
  • GitHub: signal-org (publicly available)
  • Audits: Multiple 2016-2024 by independent researchers
  • Reproducibility: ✓ Reproducible builds supported
  • Verdict: Excellent (maximum transparency)

Element

  • Code: ✓ Full open-source (Synapse, Element Web/Mobile)
  • Audits: NCC Group 2016, BSI CAOS 2023-24 (zero critical)
  • Reproducibility: ✓ Yes
  • Verdict: Excellent

SimpleX

  • Code: ✓ Full open-source (AGPL3)
  • GitHub: simplex-chat (publicly available)
  • Audits: Trail of Bits 2022 (4 issues, medium/low)
  • Reproducibility: ✓ Yes
  • Verdict: Excellent

Session

  • Code: ✓ Full open-source (GitHub session-org)
  • Audits: Quarkslab 2021 (validated PFS absent = design choice)
  • Reproducibility: ✓ Yes
  • Verdict: Good

Telegram

  • Code: ✗ Proprietary (clients only partially open)
  • MTProto: Documented but no server source access
  • Audits: No official independent audits
  • Verdict: Poor (maximum opacity)

Olvid

  • Code: ✗ Proprietary
  • Audits: ✓ ANSSI CSPN 2x (government certification)
  • Transparency: Audit publicly available, source evaluated by ANSSI
  • Verdict: Good (certified but closed)

XMPP

  • Code: ✓ Full open-source (protocol + clients)
  • Audits: Radically Open Security 2016
  • Reproducibility: ✓ Yes (protocol-agnostic)
  • Verdict: Excellent

6. JURISDICTION & COMPLIANCE

Signal

  • Country: USA (Signal Foundation Delaware-based)
  • Servers: AWS/Azure (multi-cloud, variable location)
  • Legal obligations: US FOIA (confirms number = user + last login)
  • Canary warrant: ✓ Exists (annual transparency report)
  • GDPR: Partially applicable
  • Verdict: ⚠ US dependency, data legally obtainable by authorities

Element

  • Country: UK (Matrix Foundation)
  • Servers: Self-hosted or third-party
  • Legal obligations: GDPR (EU applicable)
  • Canary warrant: None published
  • Verdict: Good (EU-based, GDPR compliance)

SimpleX

  • Country: UK (SimpleX Ltd)
  • Servers: User-controlled (no global data center)
  • Legal obligations: GDPR (architecture minimizes collection)
  • Data retention: None by SimpleX (user controls)
  • Verdict: ✓ Optimal (GDPR-friendly, no central data)

Session

  • Country: Blockchain community (decentralized)
  • Servers: 2100+ Service Nodes (global)
  • Legal obligations: Multiple per node jurisdiction
  • Verdict: ⚠ Complex (each node = different jurisdiction)

Telegram

  • Country: Russia (Pavel Durov, Kremlin investors)
  • Servers: DATAIX/GlobalNet (SORM access possible)
  • Legal obligations: FSB/GRU cooperation documented
  • Financial: $2 billion corporate debt, opaque funding
  • Risk: ✗ Russian state surveillance probable
  • Investigations: Important Stories + The Insider document Kremlin links
  • Verdict: Very poor (hostile geopolitics, SORM access, surveillance state)

Olvid

  • Country: France (ANSSI certified)
  • Servers: Proprietary relays (France/EU location)
  • Legal obligations: GDPR + French sovereignty
  • Canary warrant: N/A (P2P architecture minimizes data)
  • Verdict: ✓ Excellent (French government certified)

XMPP

  • Country: Open standard (decentralized)
  • Servers: Multiple (implementation-dependent)
  • Legal obligations: GDPR if EU-based
  • Verdict: Good (depends on server choice)

7. ADVANCED FEATURES

Feature Signal Element SimpleX Session Telegram Olvid XMPP
Disappearing messages
Identity verification (QR)
Screenshot protection
Sealed Sender
Encrypted backup
Audio/video calls ✓ (beta)
Groups
Channels/Communities

8. VULNERABILITIES & INCIDENTS

Signal

  • History: Vulnerability disclosure established 2019, no critical found since
  • Responsiveness: ✓ Excellent (0-7 days patches)
  • Bug bounty: ✓ Active (HackerOne)

Element

  • 2016: NCC Group found unknown key-share attack (Megolm group)
  • 2023: BSI audit - 3 low severity, zero critical
  • Responsiveness: ✓ Good (1-2 weeks)
  • Bug bounty: ✓ Active

SimpleX

  • 2022: Trail of Bits - 2 medium, 2 low severity
    • X3DH KDF issue (fixed)
    • Rare exploitation (high difficulty required)
  • Status: 3 of 4 issues fixed in v4.2
  • Responsiveness: ✓ Fast

Session

  • 2021: Quarkslab validated PFS absent = intentional design
  • 2025: PFS + Post-quantum ML-KEM now implemented
  • Responsiveness: ✓ Good

Telegram

  • 2016-2024: 4 cryptographic vulnerabilities (Royal Holloway)
    • Message alteration
    • Plaintext recovery
    • MITM attack (rare)
  • 2025: No documented patches
  • Responsiveness: ? (non-transparent)
  • Verdict: ✗ Poor transparency

Olvid

  • 2021: 1 homonym issue (resolved)
  • 2024: ANSSI recertification - no vulnerabilities
  • Responsiveness: ✓ Excellent (French certification)

XMPP

  • History: Very few (protocol 2015+ stable)
  • Responsiveness: ✓ Good (active community)

9. USAGE PROFILES & RECOMMENDATIONS

General User (standard security)

Recommendation: Signal or Element

  • Signal: Perfect balance security/usability, proven protocol
  • Element: More control, open-source, federation

Avoid: Telegram (no default E2EE)

Activist/Whistleblower

Recommendation: SimpleX or Olvid

  • SimpleX: Zero identifiers, encrypted metadata, PQKE
  • Olvid: ANSSI certified, P2P architecture, no social graph history

Avoid: Signal (phone required), Telegram (Kremlin surveillance)

Enterprise/Government

Recommendation: Olvid or Element (self-hosted)

  • Olvid: ANSSI certified, France compliant
  • Element: Self-host Synapse, full control, GDPR

Paranoid/High-threat

Recommendation: SimpleX + Tor + air-gap

  • Metadata encryption, zero ID, continuous PQKE
  • Self-host SMP servers
  • Hybrid multi-app (SimpleX + Olvid redundancy)

Maximum privacy-conscious

Recommendation: SimpleX > Session > Element (self-hosted)

  • SimpleX: No global ID, queue rotation
  • Session: Random ID, decentralized (minus Sybil risk)
  • Element: Federated = reduced trust vs Signal

10. CONCLUSION & FINAL SCORES

Ranking by Primary Use

  1. SimpleX (92/100): Best absolute anonymity + PQKE, for demanding users
  2. Olvid (87/100): ANSSI certified, recommended France/Government
  3. Signal (85/100): Balanced gold standard, phone number risk
  4. Element (78/100): Excellent federation, implementation-dependent
  5. Session (76/100): Decentralized but Sybil risk, PFS now in v2
  6. XMPP (74/100): Solid protocol, client-dependent
  7. Telegram (42/100): ✗ Not recommended (weak MTProto, Kremlin, optional E2EE)

Geopolitical Recommendations

  • Europe/France: Olvid (certified), Element (self-host), SimpleX
  • USA: Signal (metadata risk), SimpleX, Element
  • Hostile regions: SimpleX + Tor, Olvid + VPN
  • Critical activists: SimpleX only

Key Audit Findings 2025-2026

✓ Signal Protocol = gold standard (audits validate protocol + implementation)
✓ SimpleX = anonymity innovation + PQKE, for early adopters
✓ Olvid = French certification = government assurance
⚠ Element = good but federation metadata = leakage
⚠ Session = improving (PFS 2025, PQKE) with Sybil risk
✗ Telegram = Kremlin surveillance documented, weak MTProto
✗ XMPP = implementation variable, client-dependent


Full Report:

Canal Telegram - Chat Privacy & Cyber

Groupe SimpleX - Alternative privacy-first of Telegram

Sources: https://rentry.co/SOURCES-AUDIT-SECURE-MESSAGERIES-2026

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Pub: 11 Jan 2026 01:03 UTC

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