Features
Tessera closes the gap between messaging that authenticates and messaging that hides metadata. It does both at once — nine capabilities across authentication, metadata privacy, and a decentralized network. Every number below is reproducible from theE1–E7 experiment harnesses.
Authentication
Schnorr ZK sender authentication
A non-interactive Schnorr / Fiat–Shamir zero-knowledge proof over SECP256k1 lets a sender prove they hold the secret key — and nothing more. Unforgeability reduces to the discrete-logarithm assumption (EUF-CMA under DLog).
Zero authentication gaps
Against tamper, swap-key, forge, and replay attacks over 5000 trials each, the verifier records a false-accept rate and false-reject rate of 0/0 (experiment E6). Every forgery is rejected; every honest proof is accepted.
64-byte proofs, 0.85 ms to generate
A proof is the pair (R ‖ s) — 64 bytes on the wire. Generation takes ~0.85 ms and verification ~13 ms (experiment E1), fast enough to add no perceptible latency to a delivery.
Metadata privacy
Per-recipient blinded pseudonyms
Each delivery uses Y' = Y + t·G with t = H(seed ‖ session_id). Only a contact holding the shared seed can recompute t; everyone else sees a uniform, unlinkable pseudonym — cross-recipient and cross-delivery unlinkability.
(ε,δ)-differentially-private cover traffic
Load-independent shifted-Laplace noise makes each published per-bucket count (ε,δ)-differentially private. At ε=0.1 an adversary classifier reaches AUC 0.526 — within Monte-Carlo error of the 0.5 random baseline (experiment E3).
AES-256-GCM authenticated encryption
Message payloads are sealed with AES-256-GCM. The routing key is derived from a commitment, so the ciphertext, the routing tag, and the pseudonym all leak nothing about the sender–recipient relationship.
Network & operations
Bucketed broadcast routing
Commitments map to one of 64 buckets; recipients match with Bloom fingerprints. Bucketing gives k ≥ 75 anonymity at default parameters (experiment E2) without a central mix or trusted coordinator.
Decentralized relay overlay
Self-hosted WebSocket relays gossip proofs peer-to-peer in a mesh or ring topology with runtime churn support and proof deduplication. Mesh maintains 100% delivery at 50% node offline (experiment E5).
Runs on commodity hardware
A single node handles 326 subscribe ops/s (4.5× the naive baseline) and 440 route ops/s at ~75 subscribers per bucket (experiment E4). No dedicated mix infrastructure required.
The one feature that matters
Signed messengers authenticate the sender but leak the social graph. Metadata-private designs hide the graph but cannot authenticate. Tessera is the first protocol to deliver zero unintended metadata leaks and zero authentication gaps in the same message. See how it compares toSignal,Nym, andTor, or read theprotocol explainers. Tessera is a project ofSkelf Research.