Transient Access

Every new handle starts with transient access — valid only for the current transaction. This is the default: no additional call is needed to grant it, and it expires automatically at the end of the transaction.

Why allowThis is the most important call

When a handle is created inside a transaction, the calling contract has transient access to it. Once the transaction ends, that access is gone. Without calling allowThis, the contract will not be able to use the handle in any future transaction — including storing and reading it in the next call.

// ❌ The contract loses access to newBalance after this transaction
euint256 newBalance = Nox.add(balance, deposit);
_balances[msg.sender] = newBalance;

// ✅ The contract retains access across future transactions
euint256 newBalance = Nox.add(balance, deposit);
Nox.allowThis(newBalance);
_balances[msg.sender] = newBalance;

allowThis is a shorthand for allow(handle, address(this)) — it grants the calling contract persistent admin access to the handle.

function allowThis(euint256 value) internal

A common pattern for a balance update:

euint256 newBalance = Nox.add(balance, deposit);
Nox.allowThis(newBalance);                 // contract keeps access
Nox.allow(newBalance, msg.sender);         // user can compute with this handle
Nox.addViewer(newBalance, msg.sender);     // user can decrypt their balance
_balances[msg.sender] = newBalance;

Passing handles between contracts (allowTransient)

allowTransient grants one-time access to another address or contract for the current transaction only. The access expires automatically — no revoke is needed.

function allowTransient(euint256 value, address account) internal

This is useful when delegating a computation to a helper contract within the same transaction without giving it permanent access:

// Grant the helper contract access to compute with the handle
Nox.allowTransient(encryptedAmount, address(helperContract));
helperContract.process(encryptedAmount);
// After the transaction ends, helperContract can no longer access encryptedAmount

INFO

allowTransient is not a substitute for granting viewer or admin access to a user. It is scoped to contracts interacting within the same transaction.

allowThis vs allowTransient

	allowThis	allowTransient
Who gets access	The calling contract	Any address or contract
Duration	Persistent (across transactions)	Current transaction only
Permission level	Admin	Admin (transient)
Typical use	Store a handle the contract will reuse	Pass a handle to a helper within the same tx