canic-core 0.26.3

#[cfg(feature = "auth-crypto")]
use crate::cdk::mgmt::{
    EcdsaCurve, EcdsaKeyId, EcdsaPublicKeyArgs, SignWithEcdsaArgs, ecdsa_public_key,
    sign_with_ecdsa,
};
use crate::{InternalError, cdk::types::Principal};
use k256::ecdsa::{Signature, VerifyingKey, signature::hazmat::PrehashVerifier};
use thiserror::Error as ThisError;

///
/// EcdsaOpsError
///

#[derive(Debug, ThisError)]
pub enum EcdsaOpsError {
    #[error("threshold ecdsa management support is not enabled in this canister build")]
    ThresholdEcdsaUnavailable,

    #[error("ecdsa public key call failed: {0}")]
    PublicKeyCall(String),

    #[error("ecdsa sign call failed: {0}")]
    SignCall(String),

    #[error("invalid ecdsa public key: {0}")]
    InvalidPublicKey(String),

    #[error("invalid ecdsa signature: {0}")]
    InvalidSignature(String),
}

impl From<EcdsaOpsError> for InternalError {
    fn from(err: EcdsaOpsError) -> Self {
        crate::ops::ic::IcOpsError::from(err).into()
    }
}

///
/// EcdsaOps
///

pub struct EcdsaOps;

#[cfg(feature = "auth-crypto")]
impl EcdsaOps {
    // Sign a pre-hashed payload using the configured threshold ECDSA key.
    pub async fn sign_bytes(
        key_name: &str,
        derivation_path: Vec<Vec<u8>>,
        msg_hash: [u8; 32],
    ) -> Result<Vec<u8>, InternalError> {
        let args = SignWithEcdsaArgs {
            message_hash: msg_hash.to_vec(),
            derivation_path,
            key_id: EcdsaKeyId {
                curve: EcdsaCurve::Secp256k1,
                name: key_name.to_string(),
            },
        };

        let response = sign_with_ecdsa(&args)
            .await
            .map_err(|err| EcdsaOpsError::SignCall(err.to_string()))?;

        Ok(response.signature)
    }

    // Fetch a SEC1-encoded threshold ECDSA public key for the requested path.
    pub async fn public_key_sec1(
        key_name: &str,
        derivation_path: Vec<Vec<u8>>,
        canister_id: Principal,
    ) -> Result<Vec<u8>, InternalError> {
        let args = EcdsaPublicKeyArgs {
            canister_id: Some(canister_id),
            derivation_path,
            key_id: EcdsaKeyId {
                curve: EcdsaCurve::Secp256k1,
                name: key_name.to_string(),
            },
        };

        let response = ecdsa_public_key(&args)
            .await
            .map_err(|err| EcdsaOpsError::PublicKeyCall(err.to_string()))?;

        Ok(response.public_key)
    }
}

#[cfg(not(feature = "auth-crypto"))]
impl EcdsaOps {
    // Fail closed when threshold ECDSA management support is not compiled in.
    #[allow(clippy::unused_async)]
    pub async fn sign_bytes(
        _key_name: &str,
        _derivation_path: Vec<Vec<u8>>,
        _msg_hash: [u8; 32],
    ) -> Result<Vec<u8>, InternalError> {
        Err(EcdsaOpsError::ThresholdEcdsaUnavailable.into())
    }

    // Fail closed when threshold ECDSA public-key fetch support is not compiled in.
    #[allow(clippy::unused_async)]
    pub async fn public_key_sec1(
        _key_name: &str,
        _derivation_path: Vec<Vec<u8>>,
        _canister_id: Principal,
    ) -> Result<Vec<u8>, InternalError> {
        Err(EcdsaOpsError::ThresholdEcdsaUnavailable.into())
    }
}

impl EcdsaOps {
    // Report whether threshold ECDSA management support is compiled into this build.
    #[must_use]
    pub const fn threshold_management_enabled() -> bool {
        cfg!(feature = "auth-crypto")
    }

    // Verify a pre-hashed signature locally with k256 on every canister build.
    pub fn verify_signature(
        public_key_sec1: &[u8],
        msg_hash: [u8; 32],
        signature_bytes: &[u8],
    ) -> Result<(), InternalError> {
        let verifying_key = VerifyingKey::from_sec1_bytes(public_key_sec1)
            .map_err(|err| EcdsaOpsError::InvalidPublicKey(err.to_string()))?;
        let signature = Signature::try_from(signature_bytes)
            .map_err(|err| EcdsaOpsError::InvalidSignature(err.to_string()))?;

        verifying_key
            .verify_prehash(&msg_hash, &signature)
            .map_err(|err| EcdsaOpsError::InvalidSignature(err.to_string()))?;

        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::EcdsaOps;
    use k256::ecdsa::{SigningKey, signature::hazmat::PrehashSigner};

    #[test]
    fn verify_signature_accepts_valid_prehash_without_signing_feature() {
        let hash = [7u8; 32];
        let signing_key = SigningKey::from_bytes((&[9u8; 32]).into()).expect("signing key");
        let signature: k256::ecdsa::Signature =
            signing_key.sign_prehash(&hash).expect("prehash signature");
        let public_key = signing_key
            .verifying_key()
            .to_encoded_point(true)
            .as_bytes()
            .to_vec();

        EcdsaOps::verify_signature(&public_key, hash, &signature.to_bytes())
            .expect("local k256 verification must work in default builds");
    }
}