I was wondering for a while, how can I recognize if an Account Identifier is from my dapp or from another one. I found a solution, but I will walk you through the process first.
The benefits are a lot. It would be helpful if we wanted to warn the user, that sending to an account, which may belong to another dapp, may not support the token you are sending.
Sending fungible or non-fungible tokens to an address that doesn’t support them is kind of trapping them.
Retrieving them back without dapp developers doing something, will require one to take the dapps session private keys and use them in their own custom script. Hardly a good user experience.
The solutions which WON’T work:
One solution would be, to keep a list of all addresses the dapp ever created inside a canister and query it, but that is hitting a lot of bad design checkboxes.
Another would be to prefix addresses like NFTAf24380db6b95c504626c9e827c61e4ff42ce5e064f4e012585640868d831c61e
which would work if it was part of the standard, but it’s not. So while it can work within your dapp, trying to send to an account like that from Binance will result in an error.
The address is actually a crc32 checksum + sha224 hash. These are also one-way functions and you cant find the subaccount or any of the inputs
What’s left - If you ever played with one of those scripts which create vanity names, they are creating a ton of addresses and checking if the first letters match your input text.
Luckily even with an unoptimized algorithm, I got tens of hits within one second of calculations while looking for “888”
I like that! Instead of developers creating accounts 0 subaccount, they will choose a prefix and search for it starting from subaccount 0,1,2,3,4… until it’s found.
From there on, when sending tokens to an address, the dapp will know with certainty that they do not belong, while having few false positives (unless everyone uses this system)
So what is next - Well, everyone can use that system without anyone’s permission and pick any prefix, but I suppose it’s best if we create a community-maintained canister which keeps these prefixes and who they belong to, along with a list of supported tokens.
Let me visualize it:
888 - EXT, ANV, DIP20
432 - DIP20
A00 - NFTA
If that’s done, when someone tries to send a token from one dapp to an unknown address. We could query that registry and ask which tokens the target dapp supports.
Anyway, I am calling dibs on A00 for Anvil