Avoid pitfalls and write secure dapps
msg.sender.isAllowed(value)
.
This is important because the caller may use an existing handle that it has not access to but that the contract
has access to. In this case, depending on the contract, the caller may be to deduce or gain access to the value in used as input.
e.allowThis()
and e.allow
after an operation. By default, after the transaction is
included, no one retains access to the new handles being created and the contract will not be able to compute over them in the future,
and the user won’t be able to see them if not granted access.