Getting the same account id with dfx and with rust

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1

I’m trying to get the account id of a user and getting different things with rust and dfx.
The use case is to get the user’s subaccount of canister to transfer ICP.

But I’m getting different account ids and I’m not sure why.

This is using dfx:

dfx ledger balance --ledger-canister-id $(dfx canister id ledger) $(dfx ledger account-id --of-principal $(dfx canister id backend) --subaccount $(dfx ledger account-id --of-principal $(dfx identity get-principal)))

This is the rust implementation:

use ic_cdk::export::candid::{candid_method};

use ic_ledger_types::{AccountIdentifier, Subaccount};

use candid::{Principal};

use std::convert::TryInto;

fn principal_to_subaccount(principal_id: &Principal) -> Subaccount {
    let mut subaccount = [0; std::mem::size_of::<Subaccount>()];
    let principal_id = principal_id.as_slice();
    subaccount[0] = principal_id.len().try_into().unwrap();
    subaccount[1..1 + principal_id.len()].copy_from_slice(principal_id);

    Subaccount(subaccount)
}

#[ic_cdk_macros::query]
#[candid_method(query)]
async fn caller_account_id() -> Result<String, String> {
	let account = AccountIdentifier::new(&ic_cdk::api::id(), &principal_to_subaccount(&ic_cdk::api::caller()));
	return Ok(account.to_string());
}
2

Figured it out. It seems dfx uses a different method to calculate the subaccount that the one I used.

More info here: sdk/account_id.rs at master · dfinity/sdk · GitHub

3

It is not that dfx uses a different implementation than yours to calculate subaccounts, it’s that dfx ledger account-id is the wrong command to produce that subaccount. You want account-id(principal1, principal2); that command generates account-id(principal1, account-id(principal2, 0)). The difference is that an account ID has been sha224 hashed already, so account-id(principal2, 0) consists of completely different bytes than principal2 does.

If you want to compute principal subaccounts on the command line, use icx principal-convert --to-hex $your_principal to turn them into hex (or you can just decode them yourself - the format is just base32).

3 Likes
4

Thanks for looking into it.

I stumbled upon more problems with that dfx command indeed.
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As you correctly guessed I’m looking for something like the following in the command line:

AccountIdentifier::new(&principal1, &principal_to_subaccount(&principal2));

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Working with icx and principal-convert I got the following:

X=$(icx principal-convert --to-hex $(dfx identity get-principal) 2>&1  | cut -d ' ' -f 2); echo $(printf '%x\n' $(echo $X | wc -c | xargs -I{} expr {} / 2))$(echo $X | xargs printf "%-62s\n" | tr ' ' 0)

It seems a bit messy though. Any chance it might get better?