contract EncryptedERC20 {
// A mapping from address to an encrypted balance.
mapping(address => euint32) internal balances;

// Transfers an encrypted amount.
function _transfer(address from, address to, euint32 amount) internal {
	// Make sure the sender has enough tokens.
  TFHE.req(TFHE.le(amount, balances[from]));

  // Add to the balance of `to` and subract from the balance of `from`.
  balances[to] = TFHE.add(balances[to], amount);
  balances[from] = TFHE.sub(balances[from], amount);
}

// Returns the balance of the caller encrypted under the provided public key.
function balanceOf(
	bytes32 publicKey,
	bytes calldata signature
) public view onlySignedPublicKey(publicKey, signature) returns (bytes memory) {
	return TFHE.reencrypt(balances[msg.sender], publicKey, 0);
}