K256 (secp256k1)
K256 is a Koblitz curve that is widely used in the blockchain space (e.g. Bitcoin and Ethereum). CosmWasm offers the following APIs:
- Signature verification
- Public key recovery
Example
Signature verification
contract.rs
#[cfg_attr(not(feature = "library"), entry_point)]
pub fn query(
deps: Deps,
_env: Env,
msg: EcdsaVerifyMsg,
) -> StdResult<QueryResponse> {
let public_key = msg.public_key;
let signature = msg.signature;
let message_hash = msg.message_hash;
// Verify the signature. On chain!
let is_valid = deps.api.secp256k1_verify(&message_hash, &signature, &public_key)?;
let response = to_json_binary(&VerifyResponse {
is_valid
})?;
Ok(response)
}
Public key recovery
contract.rs
#[cfg_attr(not(feature = "library"), entry_point)]
pub fn query(
deps: Deps,
_env: Env,
msg: EcdsaRecoverMsg,
) -> StdResult<QueryResponse> {
let signature = msg.signature;
let message_hash = msg.message_hash;
let recovery_id = msg.recovery_id;
// Recover the public key. On chain!
let public_key = deps.api.secp256k1_recover_pubkey(&message_hash, &signature, recovery_id)?;
let response = to_json_binary(&RecoveryResponse {
public_key: public_key.into(),
})?;
Ok(response)
}