Glossary

coSNARK (Collaborative SNARK) A zero-knowledge proof system extended into the multi-party computation setting. Multiple parties jointly compute a witness and produce a single succinct, publicly verifiable proof, with no single party ever seeing the whole witness.

Honest-majority MPC A multi-party computation security model that stays secure as long as fewer than half of the participating parties collude. Contrasts with dishonest-majority MPC, which stays secure even if malicious parties outnumber honest ones.

MPC (Multi-Party Computation) Cryptographic techniques that let several parties jointly compute over data none of them can see in full. Each party's input stays hidden while the collective computation still produces a valid result.

Nullifier A deterministic, unpredictable identifier derived from a user's input (a passport hash, a biometric template, a phone number) that proves the same input was used before without revealing or linking the input itself. Produced by TACEO:OPRF.

ORAM (Oblivious RAM) A technique for reading and writing memory such that the access pattern itself reveals nothing about which location was accessed. Used inside TACEO:OMap.

PSS (Private Shared State) A state model that lets multiple parties keep their data private while still computing on it collaboratively. Each party's data is secret-shared and distributed across multiple nodes so no single node ever sees it in full, and coSNARKs make the resulting computation publicly verifiable.

REP3 (3-party replicated secret sharing) A secret-sharing scheme where a value x is split into three shares (x₁, x₂, x₃) such that x = x₁ + x₂ + x₃, and each of three parties holds two of the three shares. It's honest-majority: any two parties can reconstruct the secret, so the scheme stays secure as long as at least one party doesn't collude.

Secret sharing Splitting a piece of data into multiple shares distributed across separate parties, such that no individual share reveals the underlying data, but a sufficient subset of shares can reconstruct it.

TACEO Network The distributed MPC infrastructure that runs TACEO's services across independent, curated node operators, with every service output made publicly verifiable onchain via coSNARKs.

TACEO:Match Matches biometric templates across the network without any single party ever holding a template.

TACEO:OMap A verifiable oblivious map service — a private-state equivalent of Solidity's mapping primitive. Stores secrets while guaranteeing that all access patterns are hidden and all operations are provable. Built on ORAM.

TACEO:OPRF (Oblivious Pseudorandom Function) A verifiable threshold OPRF service. A client and the distributed MPC network jointly compute an output from both their secrets; the network learns nothing about the client's input or the resulting output. Used to generate nullifier seeds.

TACEO:Proof Outsources coSNARK generation to the TACEO Network. An application gets back a succinct, publicly verifiable proof without any single party seeing the underlying witness.

Witness The private input(s) a proof is generated over. In coSNARK setups (coCircom, coNoir), the witness is split and distributed across parties so no single party ever sees it in full.