TACo (Threshold Access Control)

P2P Infrastructure

A decentralised access-control layer: end-to-end encrypted data sharing and automation without a central authority that could deny service or decrypt user data. Data is encrypted to a public key, and a threshold of independently operated TACo nodes each check that a requester meets user-authored, programmable conditions (for example 'share my archive with journalists if I do not check in over seven days') before releasing a fragment of decryption material, so no single node can open the data. An experimental variant, Threshold Action Control, does conditions-based signing. Applications integrate through a software development kit, and the node network was operated by independent, collateralised nodes. The NuCypher organisation that built it is no longer active; the project is now under the stewardship of the World Ethical Data Foundation, and a relaunch centred on a 'Privacy Coalition' has been announced .

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Details

License Copyleft (AGPL-3.0 per the repository's licence metadata; the README badge links the GPL-3.0 text, so the two disagree). https://github.com/nucypher/nucypher (Python node runtime); the web SDK is documented at docs.taco.build
Dev Status ⚠️ Unmaintained
Owner Originally the NuCypher organisation and the Threshold Network; the project's documentation now states that it is under the stewardship of the World Ethical Data Foundation (the repository README calls it the World Ethical Data Forum, WEDF)
Governing Body World Ethical Data Foundation (stewardship announced in the TACo documentation); previously NuCypher, with Threshold Network documentation still referenced from the repository
Country Not stated by the project.
Start Year 2017
Stack Python node runtime (nucypher, with Solidity contracts in the repository); threshold cryptography; a web SDK (taco-web); contract addresses and architecture are documented in the TACo docs
Funding Not stated by the project.
Last Investigated Oct 29, 2026

Use Case Domains

Platform Evolution & Sovereignty Identity & Trust

Affordances

End-to-end encrypted Data portability Contextual disclosure

P2P Infrastructure Attributes

Origins Built by NuCypher to give Web3 developers an access-control layer that does not depend on a custodian, and described as running on the Threshold Network's tooling and documentation
Database N/A
Data Formats Threshold-encrypted ciphertexts with access-condition metadata; condition formats are defined in the TACo documentation
Mobile Support Library-level through the web SDK; no application
Web Support Yes: the taco-web SDK is the integration path for applications, and the documentation offers a playground and an explorer
Native Apps None: it is infrastructure used by applications
Terms Free and open source: the documentation calls it a free and open source public good, with a fee model for applications described in its docs
Funds Not stated by the project.
Based On Threshold cryptography: the README describes cryptographic primitives hosted on the decentralised nodes of the TACo network
P2P Architecture A network of independently operated nodes, each running the TACo client; groups of nodes respond collectively to requests, each providing a fragment of decryption material when the conditions are met
Overlay Network Yes: a network of TACo nodes coordinated through contracts documented in the TACo docs
Content Addressing No.
Local-First No: network infrastructure rather than a data layer.
E2EE Yes: end-to-end encrypted data sharing, with decryption possible only when a threshold of nodes cooperate and the conditions are met
Byzantine Fault Tolerance Threshold-based: a minimum number of honest nodes is needed to decrypt and a minimum number of colluding nodes to decrypt illicitly; the cited sources do not give the exact thresholds
Signature Yes in the experimental conditions-based signing variant (Threshold Action Control)
Permissions Programmable conditions authored by the data owner decide who or what may access the data; nodes verify them before responding
Protocol Maturity / Standardization A production protocol and network that is now unmaintained pending a relaunch; no standards-body involvement
Infrastructure Function Decentralised access control and key management: threshold decryption and, experimentally, threshold signing
Threat Model A centralised service or custodian that could deny access, decrypt data, or be compelled to; a single compromised node
Volunteer / Node Model Independently operated nodes, described as well collateralised, with duties, compensation and penalties documented for operators; the relaunch is to be centred on a coalition of operators from privacy and human-rights organisations
Traffic Visibility Not stated by the project.
Active Deployment Scale Not stated by the project.