Input

This document explains how to register ciphertexts to the FHEVM. Registering ciphertexts to the FHEVM allows for future use on-chain using the FHE.fromExternal solidity function. All values encrypted for use with the FHEVM are encrypted under a public key of the protocol.

// We first create a buffer for values to encrypt and register to the fhevm
const buffer = instance.createEncryptedInput(
  // The address of the contract allowed to interact with the "fresh" ciphertexts
  contractAddress,
  // The address of the entity allowed to import ciphertexts to the contract at `contractAddress`
  userAddress,
);

// We add the values with associated data-type method
buffer.add64(BigInt(23393893233));
buffer.add64(BigInt(1));
// buffer.addBool(false);
// buffer.add8(BigInt(43));
// buffer.add16(BigInt(87));
// buffer.add32(BigInt(2339389323));
// buffer.add128(BigInt(233938932390));
// buffer.addAddress('0xa5e1defb98EFe38EBb2D958CEe052410247F4c80');
// buffer.add256(BigInt('2339389323922393930'));

// This will encrypt the values, generate a proof of knowledge for it, and then upload the ciphertexts using the relayer.
// This action will return the list of ciphertext handles.
const ciphertexts = await buffer.encrypt();

With a contract MyContract that implements the following it is possible to add two "fresh" ciphertexts.

contract MyContract {
  ...

  function add(
    externalEuint64 a,
    externalEuint64 b,
    bytes calldata proof
  ) public virtual returns (euint64) {
    return FHE.add(FHE.fromExternal(a, proof), FHE.fromExternal(b, proof))
  }
}

With my_contract the contract in question using ethers it is possible to call the add function as following.

my_contract.add(ciphertexts.handles[0], ciphertexts.handles[1], ciphertexts.inputProof);