How to verify SECP256K1 signed message in smart contract? - nearprotocol

Question

I have signed the message, using ed25519
const msg = Buffer.from("hi");
const signerKeyPair = await keyStore.getKey(config.networkId, signerAccount);
const { signature } = signerKeyPair.sign(msg);
How to verify the signature in the smart contract if I have a signature and signer PublicKey?
I've found that near-core uses a near-crypto crate to do it, but I'm not sure that I can use it for the smart contracts.
an example using near-core
use near_crypto::{PublicKey, Signature, KeyType};
...
pub fn verify(&self, data: &[u8], public_key: String) -> bool {
let public_key = PublicKey::from_str(&public_key).unwrap();
let signature = Signature::empty(KeyType::SECP256K1);
signature.verify(data, &public_key)
}
...

Answer 1

Here is a solution
using ed25519-dalek = "1.0.1" crate
pub fn gimme_my_present(&mut self, signature: Vec<u8>) -> Promise {
let signature = ed25519_dalek::Signature::try_from(signature.as_ref())
.expect("Signature should be a valid array of 64 bytes [13, 254, 123, ...]");
let account_id = near_sdk::env::signer_account_id();
// Someone will give you the corresponding private key...
let public_key = ed25519_dalek::PublicKey::from_bytes(
&bs58::decode(
"H5ANpdUoXVwhYBgAgEi1ieMQZKJbwxjPJtHX4vkVcSnF",
)
.into_vec()
.unwrap(),
)
.unwrap();
near_sdk::env::log(
format!(
"Verifiying validity of signature ('{:?}') for string '{}'...",
signature, account_id
)
.as_bytes(),
);
if let Ok(_) = public_key.verify(account_id.as_bytes(), &signature) {
return Promise::new(account_id).transfer(16 * 16 * ONE_NEAR);
}
panic!("Ima no gonna give-ya the present without a signature! :-P");
}
source