Starknet gives us, developers, the power to make our contracts upgradable in a native way. Unlike in the EVM world where one has to fiddle with the inferior proxy pattern, in Starknet we can utiliz...

Multiple factors go into calculating transaction fees on Starknet. The biggest one - use of storage - is going to be addressed by 4844 in a couple of days and by additional measures later this year...

It’s very rare for the caller address (as obtained by get_caller_address()) to be zero on Starknet. Let’s examine when can this happen. The obvious case is when calling a view function. The call i...

Here’s a cool technique how to declare all of a project’s modules inside the project root (typically src/lib.cairo) without any intermediary module files. Let’s say we have a project where src/ lo...

The results are in. Congratulations to wong_ssh and 0xkaliber, the only two participants who found the attack. Job well done guys! Thank you as well to all the others who gave it a try 🙏 So what’s ...

As promised on Twitter, here’s the vulerable contract. It’s a proof of concept, but I tried to make it so that it resembles an actual contract, so there’s more than just the bare minimum for a PoC...

One of my favorite recent additions to Cairo is the StorePacking trait: trait StorePacking<T, PackedT> { fn pack(value: T) -> PackedT; fn unpack(value: PackedT) -> T; } A sup...

You know how felt division is “disabled” by default in Cairo 1? But what if we really know what we’re doing and are not afraid of shooting ourselves in the foot? It’s actually quite easy to bring i...

Here’s a pretty simple Cairo program: use debug::PrintTrait; fn calc(v1: u64, v2: u64) -> (u64, u64) { (v1 + v2, v2 * v2) } fn main() { let mut res: u64 = 0; let mut counter: u64 ...

When writing tests, we often need mock addresses to represent some entity like an account without actually deploying an initializing an account contract. The obvious thing to do is to use values li...