Privacy Architecture
An authentic technical overview of PairCrypt's privacy-by-design architecture, zero personal data collection policy, anonymous identity protection, and room isolation.
Zero Personal Data & Anonymous Identity
No Emails • No Phone Numbers • Local PairCrypt ID • Room-Scoped Mask IDs
PairCrypt never uses or collects your email address, phone number, real name, or personal identity. Communications operate using pseudonymous, locally generated cryptograms.
PairCrypt ID
When you launch the app, your phone generates a unique random ID locally. No account creation, phone verification, or email confirmation is required.
Room ID & Mask ID
When creating a room, your device generates a unique Room ID and a room-scoped Mask ID so your PairCrypt ID is never linked across different rooms.
Local Key Derivation
Room keys are computed independently on user devices using X25519 Diffie-Hellman math. Master secret keys are never transmitted across the network.
Online Rooms vs. Offline Rooms
Transient Relay Buffers • Strict Local Storage • Zero Network Leakage
PairCrypt supports two distinct room modes to balance real-time communication needs with maximum air-gapped privacy.
Online Rooms
- • Message Limits: Each message supports up to 3,000 characters (including spaces; emojis/symbols may count as multiple characters).
- • Capacity & Pairing: Up to 1,000 Online Rooms. Pairing link supports up to 7 successful pairings per 24 hours.
- • Transient Relay: Messages pass through relay servers as encrypted transit buffers, generally deleted within 3 days after delivery.
- • Subscription Requirement: At least one user in the room must hold an active subscription to chat.
Offline Rooms (Local Only)
- • Air-Gapped Creation: Turn off internet connection and create a room to produce a strictly LOCAL ONLY room.
- • No Limits: No message character limits and no cap on the number of Offline Rooms you can create.
- • Zero Server Traffic: All notes stay strictly on-device in your encrypted device vault. Zero bytes leave your phone. Pairing is disabled.
Peer-to-Peer History Sync & Key Rotation
Donor Sync Model • Master Secret Rotation • Revocation Mechanics
PairCrypt uses a peer-to-peer history donor model and key rotation to ensure both seamless participant onboarding and immediate access revocation upon kicking.
Peer-to-Peer History Donation
When a new participant joins or a member opens the app after messages have already expired and been purged from the server's transient relay, active member devices act as history donors—encrypting and transferring missing past messages directly from their local phone vault to the recipient. Please remain on the room screen for a few moments during pairing or sync to allow the history transfer to complete fully.
Key Rotation on Kick
Kicking a user rotates the room's master key—generating a brand-new Master Secret and Relay Password while invalidating the old relay authorization to permanently block future message access.
History Transparency Note: If you send messages in a room and are later kicked by another user, any newly invited participant may still see past messages previously sent, as past history is synchronized directly from remaining room members' local device vaults.
Network Anonymity & Rate Limiting
Spam Protection • Temporary Rate Limits • VPN & Tor Recommendation
PairCrypt uses rate limiting and anti-flooding controls to protect relay infrastructure while preserving network anonymity:
- Spam & Rate Limits: Attempting to flood messages triggers automatic rate limits and temporary cooldowns to maintain server relay stability.
- VPN / Tor for Accidental Cooldowns: If you encounter a temporary rate-limit block or IP cooldown, switching to a VPN or Tor or changing your IP address instantly restores access.
- Background Network Advice: Avoid leaving the app continuously open in the background without reason, as background network heartbeats can accumulate and trigger automated rate limit protections.