Writing Decrypt Result to Contract - Fhenix Documentation

This page covers the “decrypt to write tx” flow after you run decryptForTx: you take { ctHash, decryptedValue, signature } and submit a transaction that your contract can verify. There are two common patterns:

Publish: call FHE.publishDecryptResult(ctHash, plaintext, signature) so other contracts/users can reference the published result.
Verify-only: call FHE.verifyDecryptResult(ctHash, plaintext, signature) inside your contract without publishing globally.

Prerequisites

Run decryptForTx and get a result object with ctHash, decryptedValue, and signature.
Ensure the Solidity parameter type matches your encrypted type.

decryptedValue is a bigint. If your Solidity function expects a smaller integer type (e.g. uint32), make sure the value is within range.

Publish the decrypt result onchain

The intended consumer of decryptForTx is an onchain verifier such as FHE.publishDecryptResult(...). In practice, you publish the result by calling a function on your contract that invokes FHE.publishDecryptResult internally.

import '@fhenixprotocol/cofhe-contracts/FHE.sol';

// Example wrapper (adjust plaintext/result type to match your encrypted type).
function publishDecryptResult(
  bytes32 ctHash,
  uint32 plaintext,
  bytes calldata signature
) external {
  FHE.publishDecryptResult(ctHash, plaintext, signature);
}

// `decryptResult` is returned by `decryptForTx(...).execute()`
const tx = await myContract.publishDecryptResult(
  decryptResult.ctHash,
  decryptResult.decryptedValue,
  decryptResult.signature
);

await tx.wait();

Verify a decrypt result signature (without publishing)

Some protocols don’t need (or don’t want) to publish the decrypt result globally, they only need to verify that the provided plaintext and signature match a specific handle (ctHash). For example, an “unshield” flow can accept (ctHash, plaintext, signature) and only proceed if the signature is valid:

import '@fhenixprotocol/cofhe-contracts/FHE.sol';

function unshield(
  bytes32 ctHash,
  uint32 plaintext,
  bytes calldata signature
) external {
  require(
    FHE.verifyDecryptResult(ctHash, plaintext, signature),
    'Invalid decrypt signature'
  );
  // ...continue with protocol logic...
}

If you prefer to publish the result (so it can be reused elsewhere), use FHE.publishDecryptResult(...) instead.