Šepot — end-to-end encrypted messenger

Initial public release. Anonymous on-device identity (no phone number,
e-mail, or password), Signal-protocol cryptography (X3DH + PQXDH, Double
Ratchet, sealed sender) via libsignal, a metadata-minimizing relay,
group chats, disappearing messages, encrypted local storage, optional
Tor transport, and a UI localized into Czech, English, German, Russian,
and Italian.

Monorepo: Flutter client (app/), Rust relay + wire types (rust/),
protobuf definitions (proto/), self-host deploy (deploy/).

Licensed under AGPL-3.0 with an app-store distribution exception (§7).

rust/sepot-relay/migrations/0001_init.sql

@@ -0,0 +1,97 @@
+-- Šepot relay — init schéma.
+-- Klíče Curve25519 mají 33 B (libsignal serializace s type bytem 0x05),
+-- ne 32 B. ŽÁDNÝ sloupec pro IP, user-agent ani jinou PII.
+
+CREATE TABLE identities (
+    account_id     BYTEA PRIMARY KEY,
+    identity_key   BYTEA NOT NULL UNIQUE,
+    registered_at  TIMESTAMPTZ NOT NULL DEFAULT now(),
+    CHECK (octet_length(identity_key) = 33),
+    CHECK (octet_length(account_id) = 16)
+);
+
+CREATE TABLE devices (
+    device_uuid       BYTEA PRIMARY KEY,
+    account_id        BYTEA NOT NULL REFERENCES identities(account_id) ON DELETE CASCADE,
+    device_id         INTEGER NOT NULL,
+    registration_id   INTEGER NOT NULL,
+    delivery_address  BYTEA NOT NULL UNIQUE,
+    last_seen_at      TIMESTAMPTZ,
+    created_at        TIMESTAMPTZ NOT NULL DEFAULT now(),
+    UNIQUE (account_id, device_id),
+    CHECK (octet_length(delivery_address) = 32),
+    CHECK (octet_length(device_uuid) = 16)
+);
+
+CREATE INDEX idx_devices_account ON devices(account_id);
+
+CREATE TABLE signed_prekeys (
+    device_uuid    BYTEA NOT NULL REFERENCES devices(device_uuid) ON DELETE CASCADE,
+    key_id         INTEGER NOT NULL,
+    public_key     BYTEA NOT NULL,
+    signature      BYTEA NOT NULL,
+    created_at     TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (device_uuid, key_id),
+    CHECK (octet_length(public_key) = 33),
+    CHECK (octet_length(signature) = 64)
+);
+
+CREATE TABLE kyber_prekeys (
+    device_uuid    BYTEA NOT NULL REFERENCES devices(device_uuid) ON DELETE CASCADE,
+    key_id         INTEGER NOT NULL,
+    public_key     BYTEA NOT NULL,
+    signature      BYTEA NOT NULL,
+    is_last_resort BOOLEAN NOT NULL DEFAULT false,
+    created_at     TIMESTAMPTZ NOT NULL DEFAULT now(),
+    PRIMARY KEY (device_uuid, key_id),
+    CHECK (octet_length(signature) = 64),
+    CHECK (octet_length(public_key) <= 2048)
+);
+
+CREATE TABLE one_time_prekeys (
+    device_uuid    BYTEA NOT NULL REFERENCES devices(device_uuid) ON DELETE CASCADE,
+    key_id         INTEGER NOT NULL,
+    public_key     BYTEA NOT NULL,
+    PRIMARY KEY (device_uuid, key_id),
+    CHECK (octet_length(public_key) = 33)
+);
+
+CREATE INDEX idx_otp_device ON one_time_prekeys(device_uuid);
+
+CREATE TABLE message_queue (
+    msg_uuid          BYTEA PRIMARY KEY,
+    dst_address       BYTEA NOT NULL,
+    envelope          BYTEA NOT NULL,
+    enqueued_at       TIMESTAMPTZ NOT NULL DEFAULT now(),
+    expires_at        TIMESTAMPTZ NOT NULL,
+    CHECK (octet_length(envelope) <= 262144),
+    CHECK (octet_length(msg_uuid) = 16)
+);
+-- Pozn.: žádný sloupec delivered_at — ACK klienta = okamžitý hard-delete
+-- řádku, fronta se po doručení nedrží.
+
+CREATE INDEX idx_queue_dst ON message_queue(dst_address, enqueued_at);
+CREATE INDEX idx_queue_expiry ON message_queue(expires_at);
+
+CREATE TABLE push_tokens (
+    device_uuid    BYTEA PRIMARY KEY REFERENCES devices(device_uuid) ON DELETE CASCADE,
+    platform       SMALLINT NOT NULL,
+    token          BYTEA,
+    updated_at     TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+-- Klíče relaye pro sealed sender (trust root + server certificate).
+-- Trust root keypair i server keypair se generují a ukládají sem při prvním
+-- startu relaye. Sloupec trust_root_private tedy reálně obsahuje privátní
+-- klíč trust rootu. Pro produkci se doporučuje po vygenerování privátní klíč
+-- trust rootu z DB odstranit (nastavit na NULL) a jeho zálohu držet offline —
+-- k běžnému provozu relaye stačí trust_root_public, server keypair a cert.
+CREATE TABLE relay_keys (
+    id                  SMALLINT PRIMARY KEY DEFAULT 1 CHECK (id = 1),
+    trust_root_public   BYTEA NOT NULL,
+    trust_root_private  BYTEA,
+    server_public       BYTEA NOT NULL,
+    server_private      BYTEA NOT NULL,
+    server_certificate  BYTEA NOT NULL,
+    created_at          TIMESTAMPTZ NOT NULL DEFAULT now()
+);