Atlas Associates

Arc / SECURITY

Çok Katmanlı E2EE Mimarisi

Yayımlanmış mühendislik yönüne sahip ticari güvenlik ürünü

ILLUSTRATED 1:1 FLOW · 10-SECOND PREVIEW

Encrypted here.Opened there.

A message between people. Private keys stay on the devices; servers carry ciphertext and delivery data.

  1. 01
    Encrypt on device

    The message is encrypted before it leaves.

  2. 02
    Transport ciphertext

    Firestore carries ciphertext and delivery data.

  3. 03
    Open on device

    The recipient’s device decrypts the message.

FunctionsExpiry & notifications
FCMPush notification

Concept animation of one delivery path, not a recording of the app. Other paths, server-visible metadata and exceptions are documented below.

ARCHITECTURE

Arc system architecture

Explore the system diagram

Private keys are stored in the device Keychain / Keystore and never sent to servers. Messages to other people are encrypted on the device before they are sent. Phoenix hands out public PreKeys, Firestore carries ciphertext, receipts and delivery data, and Cloud Functions handle expiry deletion and notifications. Mesh bypasses servers.

One role at a time.

Open full-size diagram

Devices (iOS / Android / macOS)

Arc Protocol

1:1 · libsignal v0.96.2 · Rust FFI

  • PQXDH
  • Kyber-1024
  • Double Ratchet
Private keys
Keychain / Keystore
Decrypted text
SQLite / Hive

Message text and private keys never go to servers (except AI chats, link previews)

Explore the message flows

The dots move in the numbered order. On each of these paths, message text is encrypted on the device before it is sent.

Follow one path at a time.

Open full-size diagram
1:1 message. Post-quantum. First time: fetch B's keys. Encrypt on the device. Send ciphertext only. Notify (no content). Decrypt on B's device. Read / decrypt receipts. Only A's and B's devices can read the text

Post-quantum

1:1 message

  1. First time: fetch B's keys
  2. Encrypt on the device
  3. Send ciphertext only
  4. Notify (no content)
  5. Decrypt on B's device
  6. Read / decrypt receipts

Only A's and B's devices can read the text

On smaller screens, scroll within the diagram. Open the original using the link above.

1:1 is post-quantum (PQXDH). Group messages are not (shared key + X25519 ECIES). On Mesh, nearby Arc phones may forward the ciphertext without being able to read it. Routed relay is in development.

Arc Protocol — 1:1 encryption pipeline

Phase 1

PQXDH

Key agreement with X25519 + Kyber-1024 (post-quantum)

Phase 2

Double Ratchet

A new key for every message

Phase 3

AES-256-GCM

Encrypts message bodies and media

Technology stack

Flutter 3.44
Dart
Riverpod 2.6
Rust
Arc Protocol

App

Flutter 3.44 / Riverpod 2.6 / Rust FFI (libsignal v0.96.2)

Elixir
Phoenix
Cloud Run

Key distribution API

Elixir / Phoenix on Google Cloud Run (europe-west1)

Authentication
Firestore
Storage
Functions
Messaging
App Check
Crashlytics

Delivery and auth

Firebase (Auth / Firestore / Storage / Functions / FCM / App Check / Crashlytics)

Android
Kotlin
Swift

Mesh

BLE implementation (Dart + Android Kotlin + iOS Swift, in-house, beta)

Technical specifications

The four encryption layers

Arc core specification

Arc's core specification is ML-KEM-1024/PQXDH, E2EE for 1:1 and group chats, IGF, and offline Mesh. This Security page documents the scope and technical details.

01

PQXDH Anahtar Değişimi

Yayımlanmış mühendislik yönüne sahip ticari güvenlik ürünü

02

Double Ratchet

Yayımlanmış mühendislik yönüne sahip ticari güvenlik ürünü

03

AES-256-GCM Şifreleme

Yayımlanmış mühendislik yönüne sahip ticari güvenlik ürünü

04

XEdDSA İmzaları (libsignal)

Yayımlanmış mühendislik yönüne sahip ticari güvenlik ürünü

ML-KEM-1024 Parametreleri

POST-QUANTUM

NIST FIPS 203 standardize kuantum sonrası Anahtar Kapsülleme Mekanizması.

AlgoritmaML-KEM-1024 (via libsignal-client)
NIST Güvenlik SeviyesiSecurity category 5
Klasik Güvenlik2^128 bit (X25519)
Kuantum GüvenliğiNIST security category 5
TemelModule Lattice (FIPS 203)
Açık Anahtar Boyutu1,568 bytes
Gizli Anahtar Boyutu3,168 bytes
Şifreli Metin Boyutu1,568 bytes

Uyumluluk ve Standartlar

NIST CSF 2.0

NIST çerçevesi. 6 fonksiyonla sistematik siber risk yönetimi.

NIST SP 800-53

Federal güvenlik kontrolleri. FedRAMP temeli.

FIPS 140-3

Yayımlanmış mühendislik yönüne sahip ticari güvenlik ürünü

NIST SP 800-175B

Kriptografik algoritma seçim kılavuzu. FIPS 203 temelli.

ISO/IEC 27001

Uluslararası ISMS sertifikasyonu. B2B/B2G güven temeli.

GDPR

AB Genel Veri Koruma Yönetmeliği. Dünyanın en yüksek koruma standardı.

UK Cyber Essentials+

Birleşik Krallık hükümeti onaylı siber güvenlik sertifikasyonu.

NCSC Cloud Security

Birleşik Krallık NCSC 14 İlkesi. Bulut güvenlik değerlendirme standardı.

ABD NIST, AB GDPR, BK NCSC ve ISO'nun yayımladığı rehberler esas alınarak tasarlanmıştır. Bu bir sertifika veya üçüncü taraf denetimi değildir.