Security

Harbor is designed with security as a foundational principle. This page describes what Harbor protects against and its known limitations.

Encryption

Harbor includes modern encryption primitives and an intended end-to-end message design. The complete product send, receive, and decrypt path is not launch-ready in the current repository.

Primitive	Purpose
X25519	Key agreement (ECDH)
Ed25519	Digital signatures
XChaCha20-Poly1305	Authenticated encryption
HKDF-SHA256	Key derivation
Double Ratchet	Forward secrecy

Threat Model

Harbor is designed to protect against specific threats while acknowledging fundamental limitations.

Design Goals

• Message contents from network observers
• Message contents from blockchain observers
• Message contents from Harbor infrastructure
• Forward secrecy through Double Ratchet after ratchet blockers are fixed
• Recipient privacy through commitments after receive scanning is complete

Known Limitations

• Sender address is visible on-chain (blockchain property)
• Device count per identity is visible on-chain
• Message timing metadata is observable
• Browser-based client trusts the web application
• Device compromise exposes current and future messages

Self-Custody

Your private keys are generated and stored locally on your device. The current implementation has no Harbor-operated key server, but V1 backup and device enrollment can export encrypted identity material.

This means you are fully responsible for your keys. If you lose your device without a backup, your identity and messages are permanently lost. There is no recovery mechanism.

Privacy Commitments

•No message content is ever transmitted unencrypted
•No private keys are transmitted to a Harbor-operated server in the current architecture
•No account registration or phone number required
•No tracking, analytics, or telemetry in the client

Technical Details

For information about the protocol architecture and cryptographic implementation, see the Protocol page.

View Protocol Details