[EPIC] Generalized Shutter System and API Service | MVP

[ylembachar]

Context
Shutter’s Commit and Reveal Scheme leverages threshold encryption to provide a secure, decentralized commit-and-reveal workflow. A distributed keyper set handles critical cryptographic operations, including distributed key generation, monitoring decryption triggers, and securely releasing decryption keys. The system revolves around an on-chain registry contract where clients can register identities and time-based decryption triggers. Keypers continuously monitor this registry to ensure tamper-proof decryption key releases when trigger conditions are met. The API exposes endpoints for encryption key retrieval, decryption key access, and the decryption of commitments, providing a flexible and scalable framework. Future enhancements could include event-based and block-based triggers, P2P decryption key delivery, and WebSocket-based real-time notifications to further enhance decentralization and usability.

MVP Specification / Tasks

1. Registration Contract -> Issue: shutter-network/contracts#3

• Deploy new contract that allows registering identities and their time-based triggers
• Clients need to submit their payment during registration
• Payments are directly sent to the contract and then withdrawn by the contract’s owner (DAO’s address)
• Allows for balance withdrawal (can implement the Ownable pattern)
• Possibility to adjust the price per registration (start with zero fees)

2. Keyper Update -> Issue: shutter-network/rolling-shutter#551

• Listens to the registry contract for any new registrations
• Monitors the time-based condition to release the keys / use block timestamp (first block with timestamp > to time)
• In case of a downtime, release any keys that were supposed to be released during the downtime
• Set a sent flag on any keys that were released to avoid sending them again
• Endpoint to request old decryption keys should be open to the API to request old decryption keys if needed (already available in the keyper)
• Custom implementation under keyperimpl
• Deploy local keypers for the MVP

3. Centralized Service / API Specification -> Issue: #2

This service is a helper service that allows to use the Shutter system as follows:

• Listens to the P2P network
• Stores the decryption keys
• Exposes the below endpoints
• Has access to the keyper endpoint to retrieve old decryption keys if needed

Endpoint 1: Register Identity with Timestamp

• Allows a client to register an identity and time-based decryption trigger.
• Stores the client's identity and timestamp on the registry contract.
• Returns the encryption key for that identity.
• If the identity is not supplied, it returns a randomized identity together with the encryption key.

Endpoint 2: Get Encryption Key

• Allows a client to retrieve the encryption key for a certain identity.

Endpoint 3: Get Decryption Key

• Retrieve the decryption key once the timestamp is reached.
• Provides the decryption key to the client for local decryption.

Endpoint 4: Decrypt Commitments

• Perform decryption of encrypted commitments.
• Accepts encrypted data with an identity. Decryption keys are stored when released per identity.
• Outputs the decrypted data.

The service needs to offer the below additional functionalities:

• Stores decryption keys when released

4. Documentation
Write some documentation that allows users to use the system