Security by architecture, not by promise
QuantumChat is designed so that the people in a conversation are the only ones who can read it — backed by hybrid post-quantum cryptography and a zero-knowledge server.
Hybrid post-quantum key exchange
Every session key is derived from a hybrid of classical X25519 and post-quantum ML-KEM-1024. An adversary must break both to recover a key — closing the "harvest now, decrypt later" risk against future quantum computers.
Authenticated identities
Participants sign their key material with ML-DSA-87 identity keys, and the full handshake transcript is bound into the derived secret — so a tampered or substituted key is rejected before any data flows.
Zero-knowledge server
The relay brokers connections and stores only opaque ciphertext and minimal routing metadata. It never holds your keys and cannot read your media, messages, or files. Real-time media is peer-to-peer where the network allows.
Verified, human-checkable
Short safety codes (SAS) let two people confirm out-of-band that no one is in the middle. Identity changes are surfaced and fail-closed until you re-verify — never silently trusted.
Forward secrecy
Messaging uses a Signal-style Double Ratchet, and live calls perform coordinated key rotation, so compromise of one key does not unlock past or future communication.
Defense in depth
Authenticated transport, strict content-security policies, app attestation on sensitive endpoints, encrypted-at-rest vault sealing, and rate limiting combine to harden the surface around the cryptographic core.
Cryptographic primitives
Responsible disclosure
We welcome reports from security researchers. If you believe you've found a vulnerability, please contact support@quantumchat.cloud with details and steps to reproduce. Our cryptographic core is also intended to undergo independent third-party review.