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FHE Operation Request Flow

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Overview

This document outlines the complete flow of an FHE (Fully Homomorphic Encryption) operation request in the CoFHE ecosystem through Smart Contracts. Understanding this process is essential for developers integrating private computation capabilities into their smart contracts.

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Key Components

ComponentDescription
dAppThe decentralized application that requests FHE operations
FHE.solThe library providing FHE operation functions
Task ManagerVerifies and forwards operation requests
Slim ListenerMonitors blockchain events and forwards requests to the execution layer
Result ProcessorHandles operation results and publishes them back to the blockchain
fheOS ServerExecutes the actual FHE operations
Threshold Network(When applicable) Handles secure decryption operations

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Flow Diagram

The following diagram illustrates the complete flow of an FHE operation request in the CoFHE ecosystem:
End-to-end flow of an FHE operation request through the CoFHE system components
Figure 1: End-to-end flow of an FHE operation request through the CoFHE system components

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Step-by-Step Flow

1

Integration with Cofhejs

The decentralized application (dApp) integrates with CoFHE by utilizing Cofhejs for encryption.See in GitHub 1️⃣Encrypt request using Cofhejs, returns InEuint structure.
This step happens on the client side before blockchain interaction.
2

Requesting an FHE Operation

When the dApp needs to perform an encrypted operation within the smart contract: 2️⃣Import the FHE library in Solidity:
import "@fhenixprotocol/cofhe-contracts/FHE.sol";
Call the appropriate FHE function from the imported library:
// using trivial encrypt or the returned structures from the previous step.
function addExample(InEuint32 encryptedInput)  {
    euint32 lhs = FHE.asEuint32(encryptedInput);
    euint32 rhs = FHE.asEuint32(10);
    
    // Request an operation (addition in this example)
    euint32 result = FHE.add(lhs, rhs);
}
FHE.sol forwards the request to the Task Manager contract
3

Task Manager Processing

The Task Manager serves as the gateway for all FHE operation requests:
  1. Validate request structure to ensure all inputs are properly formatted
  2. Verify access permissions by checking if the caller has proper access to the encrypted inputs (using ACL.sol) 3️⃣
  3. Generate a unique handle that will be used to reference the future ciphertext result
  4. Return the handle to the calling dApp contract
  5. Emit an event containing the operation details for the Slim Listener to process 4️⃣
4

Slim Listener Processing

The Slim Listener monitors and forwards FHE operation requests:
  1. Listen for events from the Task Manager 5️⃣
  2. Forward request details to the fheOS server 6️⃣
5

FheOS server - FHE Operation Execution

The FheOS server handles requests:
  1. Create execution thread on the fheOS server
  2. Execute the requested operation on encrypted data
  3. Generate result ciphertext containing the encrypted result
  4. Map the handle to the actual ciphertext hash in the private storage
  5. Make result available for subsequent operations
  6. Notify the Result Processor of operation completion
6

Result Handling (For Standard Operations)

For standard FHE operations (not decryption):
  1. Update ciphertext registry with the new encrypted result 7️⃣
At this point the operation cycle is completed, preserving the confidentiality of all encrypted values.