01
Summary
PrivChat is the strictest of the seven in one specific way: your messages pass through no server, there is no account and no phone number, and everything — the key agreement, its renewal, the signatures and the envelope that says who is writing — is post-quantum.
It does not win everywhere. Signal, SimpleX and Briar have published independent audits while ours is internal; almost all of them reach more platforms and are open source. Signal and SimpleX also already protect message content against a quantum computer.
02
The full table
| Criterion | PrivChat | Telegram | Signal | SimpleX | Tox | Briar | |
|---|---|---|---|---|---|---|---|
| Works without a phone number | Yes | No | No ¹ | No | Yes | Yes | Yes |
| Works without an account | Yes | No | No | No | Yes | Yes | Yes |
| Servers everything passes through | None | Meta’s | Telegram’s | Signal’s | Relays with no identity | None | None |
| Who can know who you talk to | Nobody | Meta | Telegram ² | Signal, the minimum | Nobody | Your IP can leak | Nobody |
| End-to-end encrypted by default | Yes | Yes | Only in “secret chats” | Yes | Yes | Yes | Yes |
| Post-quantum key agreement | Yes | No | No | Yes | Yes | No | No |
| The ratchet renews post-quantum too | Yes | No | No | Yes ³ | Yes | No | No |
| Post-quantum signatures and envelope | Yes | No | No | No | No | No | No |
| Every message the same size | Yes | No | No | No | Yes | No | — |
| Sends decoys when you are not writing | Yes | No | No | No | No | No | No |
| Works with no internet | Yes: Bluetooth, local network, package or LoRa radio ⁵ | No | No | No | No | Local network only | Yes ⁴ |
| Platforms | Android, Windows and Linux | All | All | All | All | Several | Android; desktop in beta |
| Open source | No | No | Clients only | Yes | Yes | Yes | Yes |
| Security audit | Internal, by SecureAudit | Internal, by Meta | Academic review (2020) | External, published | Trail of Bits (2022 and 2024) | Unaudited | Cure53 (2017) |
¹ Telegram allows signing up with an anonymous +888 number, which is paid for.
² Since 2024 Telegram hands IP addresses and phone numbers to authorities on a valid court order.
³ Signal added the post-quantum ratchet (Triple Ratchet, SPQR) in October 2025.
⁴ Briar syncs over Bluetooth, local wifi or USB with no internet connection at all.
⁵ Since 2.10, PrivChat talks to contacts within range over the same local network or Bluetooth, in a mode both of you turn on on purpose, and by package: a file only the recipient can open, which goes as far as someone carries it; there it does not relay through third parties or look for anyone. Since 2.17 also over LoRa radio, with a Meshtastic or MeshCore node next to the phone: texts travel in encrypted pieces that other mesh nodes repeat for kilometres without being able to open them.
“—” means we could not find a public fact we can check.
Checked in September 2026 against each app’s public documentation. These things change: if you see something wrong or out of date, write to us and we will correct it.
03
Architecture and network
What separates these apps most is not how they encrypt, but where the messages travel.
| Model | Is there a server? | Network anonymity | |
|---|---|---|---|
| PrivChat | Peer-to-peer: each device is its own Tor onion service | No | Yes: everything over Tor, with padding and decoys |
| Meta’s servers, which hold a message until delivery (up to 30 days) | Yes | No | |
| Telegram | Telegram’s servers; regular chats live in its cloud | Yes | No |
| Signal | Signal’s server, which relays messages and hands out keys | Yes | No |
| SimpleX | Relays with anonymous queues; messages are deleted on delivery | Relays with no user identity | Partial: private routing; Tor optional |
| Tox | Distributed network (DHT); both ends must be online | No | No: your contacts see your IP |
| Briar | Peer-to-peer over Tor, Bluetooth, wifi or USB | No | Yes, over Tor |
04
Encryption
They all encrypt content well. The differences are in how keys are agreed and how they are renewed.
| Key agreement | Renewal | Signatures | |
|---|---|---|---|
| PrivChat | PQXDH: X25519 + ML-KEM-768 | Double Ratchet with ML-KEM-768 in every epoch | Ed25519 + ML-DSA-65, both required |
| Signal Protocol | Double Ratchet | Classical | |
| Telegram | 2048-bit Diffie-Hellman (MTProto 2.0), secret chats only | New key every 100 messages or every week, secret chats only | — |
| Signal | PQXDH: X25519 + ML-KEM (since 2023) | Triple Ratchet with SPQR, post-quantum (since 2025) | Classical |
| SimpleX | Hybrid post-quantum exchange inside the Double Ratchet | Post-quantum Double Ratchet | Classical |
| Tox | Curve25519 (NaCl) | — | — |
| Briar | Bramble protocol | — | — |
05
Post-quantum
A future quantum computer does not only break tomorrow’s traffic: it opens whatever someone recorded today. That is why it matters how far each app has gone.
| Key agreement | Renewal | Signatures | Envelope (who writes) | |
|---|---|---|---|---|
| PrivChat | Yes | Yes | Yes | Yes |
| No | No | No | No | |
| Telegram | No | No | No | No |
| Signal | Yes | Yes | No | No |
| SimpleX | Yes | Yes | No | — |
| Tox | No | No | No | No |
| Briar | No | No | No | No |
Signal and SimpleX already protect content against a quantum computer. What PrivChat adds is the signatures and the envelope: nobody can forge an identity or later work out who was writing to whom.
06
Metadata
Who talks to whom, when and how much. It often says more than the message itself.
| Who can know it | What the service keeps | Against traffic analysis | |
|---|---|---|---|
| PrivChat | Nobody: there is no service | Nothing: there is no server | Uniform size and decoys when you are not writing |
| Meta | Usage and device data, per its policy | No | |
| Telegram | Telegram | Phone number, IP and activity; handed over on court orders since 2024 | No |
| Signal | Signal, the minimum | Sign-up date and last connection date | No |
| SimpleX | Nobody | Relays hold no user identity | Uniform size |
| Tox | Your contacts see your IP | No server | No |
| Briar | Nobody | No server | — |
07
Identity and sign-up
What you have to hand over to start using it.
| Phone number | Account | How you are identified | |
|---|---|---|---|
| PrivChat | No | No | A key; added with a QR code and verified with a fingerprint |
| Yes | Yes | Phone number | |
| Telegram | Yes, or a paid anonymous +888 number | Yes | Number and username |
| Signal | Yes, to register | Yes | Number; optional username since 2024 |
| SimpleX | No | No | No persistent identifier, not even a random one |
| Tox | No | No | Public key (Tox ID) |
| Briar | No | No | Link or QR code |
08
On the device
What protects your data when someone has your phone or computer in their hands.
| Local encryption | Lock | Emergency wipe | |
|---|---|---|---|
| PrivChat | SQLCipher: system keystore key on the phone, 13-word phrase on the computer | PIN on the phone (Argon2id); phrase on the computer | Panic PIN on the phone, which destroys the keys |
| — | Biometrics or passcode | — | |
| Telegram | — | Passcode | — |
| Signal | Encrypted database | PIN, biometrics | — |
| SimpleX | Database encrypted with a passphrase | Passcode | Self-destruct passcode |
| Tox | — | — | — |
| Briar | Database encrypted with a password | Password | — |
09
What each one does differently
PrivChat
One-way channels with their own Tor address; decoys when you are not writing; post-quantum signatures and envelope; panic PIN.
The largest user base in the world; communities and group calls.
Telegram
Huge channels, bots, groups of up to 200,000 members and cloud sync.
Signal
The reference for end-to-end encryption; calls; usernames; post-quantum ratchet.
SimpleX
No user identifier at all, not even a random one; hidden profiles; incognito mode.
Tox
No infrastructure at all; several compatible clients.
Briar
Works without internet, over Bluetooth, wifi or USB; designed for crises and blackouts.
10
Where PrivChat wins and where it does not
Where it wins
- It is the only one of the seven with post-quantum signatures and a post-quantum envelope.
- It is the only one that sends decoys when you are not writing. SimpleX also makes every message the same size.
- No server, no number, no account. Briar and Tox have none either; SimpleX uses relays with no identity.
- The panic PIN destroys the keys. SimpleX has a similar self-destruct passcode.
Where it does not
- It has no independent audit: SecureAudit audits it internally. Signal, SimpleX and Briar have published ones.
- It is not open source.
- It is not on iPhone yet (in testing).
- Groups hold up to 200 people and are text-only; WhatsApp, Telegram and Signal allow far more, with photos.
- It is little known: your contacts most likely do not have it yet.
11
Sources
Checked in September 2026 against each app’s public documentation. These things change: if you see something wrong or out of date, write to privchat.wiki@proton.me and we will correct it.
- signal.org — Signal Protocol and Post-Quantum Ratchets
- simplex.chat — quantum resistance
- simplex.chat — cryptographic design review by Trail of Bits
- simplex.chat — disappearing messages
- briarproject.org — Briar Desktop
- Wikipedia — WhatsApp
- Wikipedia — Telegram
- Wikipedia — Signal
- Wikipedia — SimpleX Chat
- Wikipedia — Tox
- Wikipedia — Briar