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
- SimpleX (92/100): Best absolute anonymity + PQKE, for demanding users
- Olvid (87/100): ANSSI certified, recommended France/Government
- Signal (85/100): Balanced gold standard, phone number risk
- Element (78/100): Excellent federation, implementation-dependent
- Session (76/100): Decentralized but Sybil risk, PFS now in v2
- XMPP (74/100): Solid protocol, client-dependent
- 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