How to get AccountId from compressed public key in an ink! contract?

Question

I'm trying to do the signature verification in an ink! contract. I'm using ink_env::ecdsa_recover for this purpose.

It is returning Compressed Public Key of type [u8; 33]. I have the AccountId of the signer in the contract storage.

Is there a way I can get the AccountId from the Compressed Public Key to verify the signer? or is there a better way to approach this?

Answer 1

A compressed public key can be represented by the ECDSAPublicKey struct from the eth_compatibility crate from ink.

Try to create an ECDSAPublicKey struct from your uncompressed public key and then invoke the to_default_account_id() function from it which is defined here.

Try the following:

1. Add the eth_compatibility crate to your project
2. Import eth_compatibility::ECDSAPublicKey
3. Define an ecdsa_key from your compressed_pub_key with: let ecdsa_key=ECDSAPublicKey::from(compressed_pub_key);
4. Derive an account_id of type AccountId with: let account_id=ecdsa_key.to_default_account_id();

Answer 2

You could get the Public key (hex) using the inspect command of subkey --> Take a look at this link: enter link description here

If you already have it (for example 0xd6a3105d6768e956e9e5d41050ac29843f98561410d3a47f9dd5b3b227ab8746), add hex-literal = "0.3.4" in your Cargo.toml, and then in your ink contract, your account Id will be:

AccountId = hex_literal::hex!["d6a3105d6768e956e9e5d41050ac29843f98561410d3a47f9dd5b3b227ab8746"].into();