Instantiate2 algorithm

With the instantiate2 algorithm you can create a contract address in a predictable and deterministic way. The underlying algorithm is rather simple.

We use SHA-256 as the underlying hashing algorithm.

You need to provide the following inputs:

• Checksum: This is the checksum of the contract code (the Wasm module, for example). This has to be a SHA-256 hash
• Creator: This is the canonicalized address of the user instantiating the contract
• Salt: This is some byte string allowing you to distinguish multiple instantiations of the same contract by the same creator; this parameter has to be under 64 bytes in length
• Message: This is usually unused. CosmWasm sets this to an empty byte string

let c_checksum = concat!((checksum.len() as u64).to_be_bytes(), checksum);
let c_creator = concat!((creator.len() as u64).to_be_bytes(), creator);
let c_salt = concat!((salt.len() as u64).to_be_bytes(), salt);
let c_msg = concat!((msg.len() as u64).to_be_bytes(), msg);
 
let canonical_address = hash_sha256(
    concat!(
        hash_sha256(b"module"),
        b"wasm\0",
        c_checksum,
        c_creator,
        c_salt,
        c_msg,
    ),
);