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April 23, 2020 17:23
October 18, 2022 20:07
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A decentralized cryptological network offering accessible, intuitive, and extensible runtimes and interfaces for secrets management and dynamic access control.

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The NuCypher network provides accessible, intuitive, and extensible runtimes and interfaces for secrets management and dynamic access control.

  • Accessible - The network is permissionless and censorship-resistant. There are no gate-keepers and anyone can use it.
  • Intuitive - The network leverages the classic cryptological narrative of Alice and Bob (with additional characters where appropriate). This character-based narrative permeates the code-base and helps developers write safe, misuse-resistant code.
  • Extensible - The network currently supports proxy re-encryption but can be extended to provide support for other cryptographic primitives.

Access permissions are baked into the underlying encryption, and access can only be explicitly granted by the data owner via sharing policies. Consequently, the data owner has ultimate control over access to their data. At no point is the data decrypted nor can the underlying private keys be determined by the NuCypher network.

Under the hood, the NuCypher network uses the Umbral threshold proxy re-encryption scheme to provide cryptographic access control.

How does NuCypher work?

  1. Alice, the data owner, grants access to her encrypted data to anyone she wants by creating a policy and uploading it to the NuCypher network.

  2. A group of Ursulas, which are nodes on the NuCypher network, receive information about the policy, called a PolicyArrangement that include a re-encryption key share. The Ursulas stand ready to re-encrypt data in exchange for payment in fees and token rewards. Thanks to the use of proxy re-encryption, Ursulas and the storage layer never have access to Alice's plaintext data.

  3. Each policy created by Alice has an associated encryption key, which can be used by any entity (Enrico) to encrypt data on Alice's behalf. This entity could be an IoT device in her car, a collaborator assigned the task of writing data to her policy, or even a third-party creating data that belongs to her – for example, a lab analyzing medical tests. The resulting encrypted data can be uploaded to IPFS, Swarm, S3, or any other storage layer.

  4. Bob, a data recipient, obtains the encrypted data from the storage layer and sends an access request to the NuCypher network. If the policy is satisfied, the data is re-encrypted to his public key and he can decrypt it with his private key.

  5. Ursulas earn fees and token rewards for performing re-encryption operations.

More detailed information:



"NuCypher - A proxy re-encryption network to empower privacy in decentralized systems"

by Michael Egorov, David Nuñez, and MacLane Wilkison - NuCypher


"NuCypher - Staking Protocol & Economics"

by Michael Egorov, MacLane Wilkison, Arjun Hassard - NuCypher

"NuCypher - Pricing Protocol & Economics"

by Arjun Hassard - NuCypher


"Umbral: A Threshold Proxy Re-Encryption Scheme"

by David Nuñez

Getting Involved

NuCypher is a community-driven project and we're very open to outside contributions.

All our development discussions happen in our Discord server, where we're happy to answer technical questions, discuss feature requests, and accept bug reports.

If you're interested in contributing code, please check out our Contribution Guide and browse our Open Issues for potential areas to contribute.

Get up and running quickly by using our docker development setup


If you identify vulnerabilities with any nucypher code, please email with relevant information to your findings. We will work with researchers to coordinate vulnerability disclosure between our stakers, partners, and users to ensure successful mitigation of vulnerabilities.

Throughout the reporting process, we expect researchers to honor an embargo period that may vary depending on the severity of the disclosure. This ensures that we have the opportunity to fix any issues, identify further issues (if any), and inform our users.

Sometimes vulnerabilities are of a more sensitive nature and require extra precautions. We are happy to work together to use a more secure medium, such as Signal. Email and we will coordinate a communication channel that we're both comfortable with.

A great place to begin your research is by working on our testnet. Please see our documentation to get started. We ask that you please respect testnet machines and their owners. If you find a vulnerability that you suspect has given you access to a machine against the owner's permission, stop what you're doing and immediately email