User Decrypt Multiple Values

Decrypting multiple encrypted values (ebool, euint32, euint64) for a user. Highlights that each value requires individual permission grants, as there is no batching for FHE.allow() or FHE.allowThis().

To run this example correctly, make sure the files are placed in the following directories:

• .sol file → <your-project-root-dir>/contracts/

• .ts file → <your-project-root-dir>/test/

This ensures Hardhat can compile and test your contracts as expected.

🔐 FHE API Reference (10 items)

Types: ebool · euint32 · euint64

Functions:

• FHE.add() - Homomorphic addition: result = a + b (overflow wraps)

• FHE.allow() - Grants PERMANENT permission for address to decrypt/use value

• FHE.allowThis() - Grants contract permission to operate on ciphertext

• FHE.asEbool() - Encrypts a plaintext boolean into ebool

• FHE.asEuint32() - Encrypts a plaintext uint32 value into euint32

• FHE.asEuint64() - Encrypts a plaintext uint64 value into euint64

• FHE.xor() - Homomorphic bitwise XOR

UserDecryptMultipleValues.sol

// SPDX-License-Identifier: BSD-3-Clause-Clear
pragma solidity ^0.8.24;

import {FHE, ebool, euint32, euint64} from "@fhevm/solidity/lib/FHE.sol";
import {ZamaEthereumConfig} from "@fhevm/solidity/config/ZamaConfig.sol";

/**
 * @notice Decrypting multiple encrypted values (ebool, euint32, euint64) for a user.
 *         Highlights that each value requires individual permission grants,
 *         as there is no batching for FHE.allow() or FHE.allowThis().
 *
 * @dev Individual permissions are required for each encrypted value.
 */
contract UserDecryptMultipleValues is ZamaEthereumConfig {
    ebool private _encryptedBool;
    euint32 private _encryptedUint32;
    euint64 private _encryptedUint64;

    /// @notice Initialize multiple values from plaintext
    /// @dev FHE.asEuintX() creates encrypted constants from plaintext
    function initialize(bool a, uint32 b, uint64 c) external {
        // Create encrypted values from plaintext
        _encryptedBool = FHE.xor(FHE.asEbool(a), FHE.asEbool(false));
        _encryptedUint32 = FHE.add(FHE.asEuint32(b), FHE.asEuint32(1));
        _encryptedUint64 = FHE.add(FHE.asEuint64(c), FHE.asEuint64(1));

        // ⚠️ Why separate? No batching for permissions - each needs individual allow()
        FHE.allowThis(_encryptedBool);
        FHE.allowThis(_encryptedUint32);
        FHE.allowThis(_encryptedUint64);

        FHE.allow(_encryptedBool, msg.sender);
        FHE.allow(_encryptedUint32, msg.sender);
        FHE.allow(_encryptedUint64, msg.sender);
    }

    function encryptedBool() public view returns (ebool) {
        return _encryptedBool;
    }

    function encryptedUint32() public view returns (euint32) {
        return _encryptedUint32;
    }

    function encryptedUint64() public view returns (euint64) {
        return _encryptedUint64;
    }
}

UserDecryptMultipleValues.ts