julius.joska/sepot
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 2 Wiki Activity

docs: describe relay metadata and audit status precisely

Browse Source 
State what the relay sees at runtime (authenticated submission reveals
which device hands an envelope to which address) instead of claiming it
never learns the sender, note where data is stored, drop the
"Signal-grade" label and add a non-affiliation notice, and document
that only internal audits and penetration tests have been done so far.
This commit is contained in:
Julius Joska
2026-10-23 09:17:44 +02:00
parent d2eb0d4f8c
commit 5b237c82f2
2 changed files with 22 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
README.md
+9 -7
View File
@@ -2,16 +2,16 @@
**Šepot** is an end-to-end encrypted messenger with anonymous, on-device identity. There is no phone number, e-mail, or password: an account is a keypair generated on the device, your ID is the fingerprint of your public key, and the only backup is a mnemonic phrase.
The design goal is **metadata minimization with a public threat model** — never "zero metadata". The relay is deliberately dumb: it cannot read message content, does not learn who sent a message, and does not log IP addresses. What it *does* see is documented honestly below.
The design goal is **metadata minimization with a public threat model** — never "zero metadata". The relay is deliberately dumb: it cannot read message content, envelopes carry no sender, and it neither stores a sender–recipient link nor logs IP addresses. What it *does* see while a connection is open is documented honestly below.
> Status: 1.2.x. Android is on [Google Play](https://play.google.com/store/apps/details?id=cz.sepot.sepot); iOS is on the App Store outside the EU, with EU availability pending Apple's trader verification under the Digital Services Act. See [`CHANGELOG.md`](CHANGELOG.md).
## Features
- **Signal-grade cryptography** via the official Rust `libsignal`: X3DH + post-quantum PQXDH (Kyber-1024) key agreement, Double Ratchet, and sealed sender.
- **End-to-end encryption** via the open-source Rust `libsignal` library: X3DH + post-quantum PQXDH (Kyber-1024) key agreement, Double Ratchet, and sealed sender.
- **Anonymous identity** — no phone/e-mail/password. Recovery through a 24-word mnemonic that encodes the identity key itself (not a KDF seed).
- **Encrypted at rest** — all local data lives in SQLCipher, unlocked by a PIN (Argon2id-derived key) or biometrics. Optional **duress PIN** opens a separate empty database.
- **Group chats** — up to 128 members, pairwise fan-out so every member gets full forward secrecy; the relay never learns a group exists.
- **Group chats** — up to 128 members, pairwise fan-out so every member gets full forward secrecy; groups are not a server-side object and the relay keeps no member list.
- **Attachments** — images and files are encrypted client-side (AES-256-GCM) and uploaded as opaque blobs with a TTL; image metadata (EXIF/GPS) is stripped on send.
- **Disappearing messages**, read receipts (off by default), voice messages, replies, reactions, edits, contact verification (safety numbers).
- **Push with or without Google** — UnifiedPush/ntfy when a distributor is installed, otherwise FCM on Android (default since 1.2.0, can be switched off) and APNs on iOS. A push wake-up never carries content, sender, or count.
@@ -29,9 +29,11 @@ The design goal is **metadata minimization with a public threat model** — neve
SQLCipher at rest opaque attachment blobs
```
Every message is encrypted end-to-end with libsignal and wrapped in a sealed-sender envelope, so the relay routes by recipient delivery address without learning the sender. Undelivered messages sit in a per-recipient queue with a fixed TTL and are hard-deleted on acknowledgement.
Every message is encrypted end-to-end with libsignal and wrapped in a sealed-sender envelope, so the envelope itself carries no sender and the relay routes it by the recipient's delivery address. Undelivered messages sit in a per-recipient queue with a fixed TTL and are hard-deleted on acknowledgement.
**What the relay can see:** the recipient's delivery address, message size, and timing. **What it cannot see:** message content, the sender's identity, group membership, or (with logging disabled as shipped) client IP addresses. The full model — including where the trust boundary sits — is in [`THIRD-PARTY-NOTICES.md`](THIRD-PARTY-NOTICES.md) and the crypto facade `app/lib/core/crypto/`.
**What the relay can see:** the recipient's delivery address, envelope size and timing, push tokens, and — while a connection is open — the client IP address. Envelopes are submitted over an authenticated WebSocket, so at runtime the relay also knows which connected device hands an envelope to which delivery address; it needs that to deliver. **What it does not see or keep:** message content, names, contacts or group membership. It stores no sender–recipient link and no IP addresses, and writes neither to its logs. Someone who took over the relay could start recording runtime metadata; they still could not read messages. See [`SECURITY.md`](SECURITY.md) and the crypto facade `app/lib/core/crypto/`.
**Where data lives:** messages, accounts and keys are stored only on servers in the EU (Hetzner, Germany). Message content never leaves the device unencrypted. Nothing leaves the EU except an anonymous wake-up push via Google (FCM) or Apple (APNs), which carries no message content or sender; the website runs behind Cloudflare.
## Repository layout
@@ -71,10 +73,10 @@ UI strings live in `app/lib/l10n/app_*.arb` (`cs`, `en`, `de`, `ru`, `it`) and a
## Security
Cryptography is implemented by Signal's `libsignal`, not by hand-rolled primitives. If you find a vulnerability, please report it privately to **security@sepot.cz** rather than opening a public issue — see [`SECURITY.md`](SECURITY.md) and [`/.well-known/security.txt`](https://sepot.cz/.well-known/security.txt).
Cryptography is implemented by the open-source `libsignal` library, not by hand-rolled primitives. Šepot is not affiliated with Signal Messenger LLC; Signal is a trademark of its owner. The project runs regular internal security audits and penetration tests (August, September and October 2026); no independent third-party audit has taken place yet. If you find a vulnerability, please report it privately to **security@sepot.cz** rather than opening a public issue — see [`SECURITY.md`](SECURITY.md) and [`/.well-known/security.txt`](https://sepot.cz/.well-known/security.txt).
## License
Šepot is licensed under the **GNU Affero General Public License v3.0** — see [`LICENSE`](LICENSE).
The license includes an **AGPL §7 additional permission for app-store distribution**: Šepot may be distributed through App Store / Google Play provided the complete corresponding source stays available under the AGPL through a channel *without* those store restrictions (this repository and the direct APK releases). That permission covers only Šepot's own code. The bundled Signal `libsignal` is AGPL-3.0 held by Signal Messenger, LLC — its app-store status is documented in [`THIRD-PARTY-NOTICES.md`](THIRD-PARTY-NOTICES.md).
The license includes an **AGPL §7 additional permission for app-store distribution**: Šepot may be distributed through App Store / Google Play provided the complete corresponding source stays available under the AGPL through a channel *without* those store restrictions (this repository and the direct APK releases). That permission covers only Šepot's own code. The bundled `libsignal` is AGPL-3.0 held by Signal Messenger, LLC — its app-store status is documented in [`THIRD-PARTY-NOTICES.md`](THIRD-PARTY-NOTICES.md).
SECURITY.md
+13 -4
View File
@@ -28,7 +28,16 @@ reproduce almost everything.
## What the relay can and cannot see
The threat model is documented in the README: the relay sees routing tokens,
message sizes, timing and push tokens, never content or sender identity.
Reports that demonstrate the relay learning more than that are the ones we
care about most.
The threat model is documented in the README. In short: envelopes carry no
sender (sealed sender) and the relay never sees content. It does see routing
tokens, envelope sizes, timing and push tokens, and while a connection is
open the client IP and which authenticated device submits an envelope to
which delivery address. It stores no sender–recipient link and no IP
addresses. Reports that demonstrate the relay learning or keeping more than
that are the ones we care about most.
## Audits
We run regular internal security audits and penetration tests (August,
September and October 2026); fixes are listed in `CHANGELOG.md`. No
independent third-party audit has taken place yet.