trussed 0.2.0-rc.1

Modern Cryptographic Firmware
Documentation 
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use trussed_core::{
    api::{reply, request},
    types::Signature,
    Error,
};

use crate::key;
use crate::service::MechanismImpl;
use crate::store::Keystore;

impl MechanismImpl for super::HmacSha512 {
    #[inline(never)]
    fn derive_key(
        &self,
        keystore: &mut impl Keystore,
        request: &request::DeriveKey,
    ) -> Result<reply::DeriveKey, Error> {
        use hmac::{Hmac, Mac};
        type HmacSha512 = Hmac<sha2::Sha512>;

        let key = keystore.load_key(key::Secrecy::Secret, None, &request.base_key)?;
        if !matches!(key.kind, key::Kind::Symmetric(..) | key::Kind::Shared(..)) {
            return Err(Error::WrongKeyKind);
        }
        let shared_secret = key.material;

        let mut mac =
            HmacSha512::new_from_slice(shared_secret.as_ref()).map_err(|_| Error::InternalError)?;

        if let Some(additional_data) = &request.additional_data {
            mac.update(additional_data);
        }
        let derived_key: [u8; 64] = mac.finalize().into_bytes().into();

        let key = keystore.store_key(
            request.attributes.persistence,
            key::Secrecy::Secret,
            key::Kind::Symmetric(64),
            &derived_key,
        )?;

        Ok(reply::DeriveKey { key })
    }

    #[inline(never)]
    fn sign(
        &self,
        keystore: &mut impl Keystore,
        request: &request::Sign,
    ) -> Result<reply::Sign, Error> {
        use hmac::{Hmac, Mac};
        use sha2::Sha512;
        type HmacSha512 = Hmac<Sha512>;

        let key = keystore.load_key(key::Secrecy::Secret, None, &request.key)?;
        if !matches!(key.kind, key::Kind::Symmetric(..) | key::Kind::Shared(..)) {
            return Err(Error::WrongKeyKind);
        }
        let shared_secret = key.material;

        let mut mac =
            HmacSha512::new_from_slice(shared_secret.as_ref()).map_err(|_| Error::InternalError)?;

        mac.update(&request.message);
        let result = mac.finalize();
        let signature = Signature::try_from(&*result.into_bytes()).unwrap();

        Ok(reply::Sign { signature })
    }
}