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Security Model

Built on proven cryptography with no shortcuts or compromises.

Encryption

1 Key Exchange: X25519

Elliptic curve Diffie-Hellman over Curve25519. Every message uses ephemeral sender keys, so a compromised sender key does not expose other messages.

2 Symmetric Encryption: XChaCha20-Poly1305

AEAD cipher providing both confidentiality and authenticity. 256-bit keys with 192-bit nonces (safe for random generation). Designed by Daniel J. Bernstein, resistant to timing attacks, and faster than AES on devices without hardware acceleration.

3 Digital Signatures: Ed25519

EdDSA signatures for identity verification and message authentication. Fast, deterministic, and resistant to side-channel attacks. Your identity is a 256-bit Ed25519 public key.

Web of Trust Identity

Unlike centralized messengers, Sygnet doesn't rely on phone numbers, emails, or any central authority. Your identity is self-certifying.

Five Trust Levels

In-Person Verified

Highest trust. Identity confirmed through in-person QR code exchange.

SAS Verified

Identity confirmed via Short Authentication String comparison over a trusted channel.

Web of Trust (1-Hop)

Introduced directly by a contact you have personally verified.

Web of Trust (2-Hop)

Introduced through two steps in the trust chain. Lower confidence, but still traceable.

Unverified

New contacts not yet verified. Messages are still encrypted, but you should verify their identity before trusting sensitive content.

Network Privacy

Tor Integration

Tor routing hides your IP address from message recipients and observers. Your .onion address is derived from your identity key.

DHT Discovery

Decentralized Hash Table for finding contacts without central servers. No company controls who can message whom.

No Metadata Logging

We don't run central servers, so we can't log metadata. There's no database of who messages whom or when.

Peer-to-Peer

Messages travel directly between you and your contact. No relay servers to intercept or subpoena.

Tor Relay Commitment

Sygnet depends on Tor. Rather than just consuming bandwidth, we run middle relay nodes to give back to the network we rely on. More relays mean faster connections and stronger privacy for everyone -- not just Sygnet users.

Anti-Spam

Without central servers to filter messages, Sygnet uses multiple layers of defense to prevent abuse.

1 Computational Cost for Cold Messages

Your first message to someone new requires your device to solve a small puzzle — it takes about 30-60 seconds in the background, and you won't notice it. But a spammer trying to message thousands of people would need to solve thousands of puzzles, making mass spam impractical. Puzzles expire after 24 hours so they can't be stockpiled.

2 Your Contacts Are Your Allowlist

Messages from people you know — verified contacts and friends-of-friends — are accepted immediately. Only strangers need to solve the puzzle. Your trust network is your first line of defense.

3 Introduction Limits

Each contact can introduce you to at most 5 new people per day. This prevents anyone from flooding your inbox through the trust chain. Introductions expire after 7 days and can't be reused.

Threat Model

We believe in honest communication about security. Here's what Sygnet does and doesn't protect against.

We Protect Against

  • ✓ Mass surveillance of message content
  • ✓ Central authority reading your messages
  • ✓ Identity spoofing (with verification)
  • ✓ Message modification in transit
  • ✓ Network observers seeing message content
  • ✓ Server compromise (there is no server)
  • ✓ Spam floods (proof-of-work + trust-based filtering)

Limitations

  • ✗ Compromised device (malware on your computer)
  • ✗ Recipient sharing your messages
  • ✗ Traffic analysis without Tor
  • ✗ Lost/stolen device without encryption
  • ✗ Rubber-hose cryptanalysis (coercion)

Audits & Transparency

Verifiable Protocols

Sygnet uses published cryptographic protocols built on proven primitives. No proprietary magic. You can verify the math without trusting us.

Security Audit

Professional security audit planned. We'll publish the full report when complete.

Responsible Disclosure

Found a vulnerability? Email security@getSygnet.com. We appreciate responsible disclosure.