Add function that calculates ledger account from a principal

[kentosugama]

Feature requested by community: https://dx.internetcomputer.org/topic/180

Requires a SHA224 and CRC32 implementation. Implementation taken from Timo's implementation:
https://github.com/research-ag/sha2

[chenyan-dfinity]

Is this the ledger account? I think we don't want to append CRC32 at the end.

Also, not sure if this belongs to base. Timo's sha224 library is way better than what we include here. I happen to wrote a version based on his library: https://github.com/dfinity/canister-profiling/blob/main/crypto/motoko/src/sha.mo#L16

[kentosugama]

I asked Timo if I could include his implementation here and he said yes.

It seems that converting Principal to Account is a basic enough function to have it in base. I hid the cryptographic functions as private functions though.

I will look into where the CRC32 is coming from.

[ZenVoich]

Won't it be confused with ICRC1 account?

Personally, I’m used to the fact that ledger account is accountId

[kentosugama]

It looks like the Ledger documentation specifies the prepending of the CRC32 hash

https://internetcomputer.org/docs/current/references/ledger#_accounts

[chenyan-dfinity]

Interesting. Better to clarify with the ledger team, because their code doesn't have CRC32 either: https://github.com/dfinity/ic/blob/master/rs/rosetta-api/icp_ledger/src/account_identifier.rs#L58

[kentosugama]

I just tried making a call to the Ledger Canister with and without the CRC checksum. The call without the checksum failed.
The code you linked to has logic for checking the checksum. I think internally, they strip off the CRC but the public interface requires it. (https://github.com/dfinity/ic/blob/a6d4159013996396c84ca33f54dd60f2c5e17ea0/rs/rosetta-api/icp_ledger/ledger.did#L13)

[kentosugama]

@ZenVoich that's a fair feedback and seems consistent with the documentation.

Maybe it should be called toAccountID(), toLedgerAccount(), or even toLedgerAccountId()

[kentosugama]

https://m7sm4-2iaaa-aaaab-qabra-cai.ic0.app/?tag=1188592470

This example seems to clearly show you need the CRC32.

[crusso]

Looks good to me, though slightly overkill since principals are short.
However, since this a user request, let's get it in.

I guess another design would be to parameterize by the sha244 implementation, but perhaps that's too risky. Or add a separate Ledger library that contains this (and in future other Ledger related logic). I expect many programs will use Principal, but not need the Ledger functionality.

I'll let @chenyan-dfinity decide...

[chenyan-dfinity]

All good. I just realized that in the Rust implementation, the to_vec() method actually prepend the CRC32, so we are all good!

[timohanke]

Just for completeness, commenting here on an already merged PR, and too minor to be worth opening this again. So just for the record.

Since we are only using Sha224 I would have hard-codes the values here and remove the ivs array entirely since it also includes IVs for Sha256 which is confusing.