Initial support for the key injection and derivation

These are the features required by Nitrokey Webcrypt.

Cargo.toml

@@ -19,12 +19,17 @@ delog = "0.1.6"
 littlefs2 = "0.4.0"
 serde-byte-array = "0.1.2"
 
+# For hmacsha256p256
+hmac = { version = "0.12", optional = true }
+sha2 = { version = "0.10", default-features = false, optional = true }
+
 [dev-dependencies]
 trussed = { version = "0.1.0", default-features = false, features = ["serde-extensions", "virt"] }
 
 [features]
 default = []
 
+hmacsha256p256 = ["hmac", "sha2"]
 wrap-key-to-file = ["chacha20poly1305"]
 chunked = []
 encrypted-chunked = ["chunked", "chacha20poly1305/stream"]

src/hmacsha256p256/mod.rs

@@ -0,0 +1,239 @@
+// Copyright (C) Nitrokey GmbH
+// SPDX-License-Identifier: Apache-2.0 or MIT
+
+use serde::{Deserialize, Serialize};
+use trussed::types::SerializedKey;
+use trussed::{
+    client::ClientError,
+    key::{self, Kind},
+    serde_extensions::{Extension, ExtensionClient, ExtensionImpl, ExtensionResult},
+    service::{Keystore, ServiceResources},
+    types::{Bytes, CoreContext, KeyId, Location, Mechanism},
+    Error,
+};
+
+#[derive(Debug, Default)]
+pub struct HmacSha256P256Extension;
+
+#[derive(Debug, Deserialize, Serialize)]
+#[allow(missing_docs)]
+pub enum HmacSha256P256Request {
+    DeriveFromHash(request::DeriveFromHash),
+    InjectAnyKey(request::InjectAnyKey),
+}
+
+mod request {
+    use super::*;
+    use serde::{Deserialize, Serialize};
+    use trussed::types::{KeyId, Location, Mechanism, Message, SerializedKey};
+    use trussed::Error;
+
+    #[derive(Debug, Deserialize, Serialize)]
+    pub struct DeriveFromHash {
+        pub mechanism: Mechanism,
+        pub key: KeyId,
+        pub location: Location,
+        pub data: Option<Message>,
+    }
+
+    impl TryFrom<HmacSha256P256Request> for DeriveFromHash {
+        type Error = Error;
+        fn try_from(request: HmacSha256P256Request) -> Result<Self, Self::Error> {
+            match request {
+                HmacSha256P256Request::DeriveFromHash(request) => Ok(request),
+                _ => Err(Error::InternalError),
+            }
+        }
+    }
+
+    impl From<DeriveFromHash> for HmacSha256P256Request {
+        fn from(request: DeriveFromHash) -> Self {
+            Self::DeriveFromHash(request)
+        }
+    }
+
+    #[derive(Debug, Deserialize, Serialize)]
+    pub struct InjectAnyKey {
+        pub location: Location,
+        pub kind: Kind,
+        pub raw_key: SerializedKey,
+    }
+
+    impl TryFrom<HmacSha256P256Request> for InjectAnyKey {
+        type Error = Error;
+        fn try_from(request: HmacSha256P256Request) -> Result<Self, Self::Error> {
+            match request {
+                HmacSha256P256Request::InjectAnyKey(request) => Ok(request),
+                _ => Err(Error::InternalError),
+            }
+        }
+    }
+
+    impl From<InjectAnyKey> for HmacSha256P256Request {
+        fn from(request: InjectAnyKey) -> Self {
+            Self::InjectAnyKey(request)
+        }
+    }
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+#[allow(missing_docs)]
+pub enum HmacSha256P256Reply {
+    DeriveFromHash(reply::DeriveFromHash),
+    InjectAnyKey(reply::InjectAnyKey),
+}
+
+mod reply {
+    use serde::{Deserialize, Serialize};
+    use trussed::{types::KeyId, Error};
+
+    use super::*;
+
+    #[derive(Debug, Deserialize, Serialize)]
+    #[non_exhaustive]
+    pub struct DeriveFromHash {
+        pub key: Option<KeyId>,
+    }
+
+    impl TryFrom<HmacSha256P256Reply> for DeriveFromHash {
+        type Error = Error;
+        fn try_from(reply: HmacSha256P256Reply) -> Result<Self, Self::Error> {
+            match reply {
+                HmacSha256P256Reply::DeriveFromHash(reply) => Ok(reply),
+                _ => Err(Error::InternalError),
+            }
+        }
+    }
+
+    impl From<DeriveFromHash> for HmacSha256P256Reply {
+        fn from(reply: DeriveFromHash) -> Self {
+            Self::DeriveFromHash(reply)
+        }
+    }
+
+    #[derive(Debug, Deserialize, Serialize)]
+    pub struct InjectAnyKey {
+        pub key: Option<KeyId>,
+    }
+
+    impl TryFrom<HmacSha256P256Reply> for InjectAnyKey {
+        type Error = Error;
+        fn try_from(reply: HmacSha256P256Reply) -> Result<Self, Self::Error> {
+            match reply {
+                HmacSha256P256Reply::InjectAnyKey(reply) => Ok(reply),
+                _ => Err(Error::InternalError),
+            }
+        }
+    }
+
+    impl From<InjectAnyKey> for HmacSha256P256Reply {
+        fn from(reply: InjectAnyKey) -> Self {
+            Self::InjectAnyKey(reply)
+        }
+    }
+}
+
+impl Extension for HmacSha256P256Extension {
+    type Request = HmacSha256P256Request;
+    type Reply = HmacSha256P256Reply;
+}
+
+pub fn derive_key_from_hash(
+    keystore: &mut impl Keystore,
+    request: &request::DeriveFromHash,
+) -> Result<reply::DeriveFromHash, Error> {
+    use hmac::{Hmac, Mac};
+    type HmacSha256P256 = Hmac<sha2::Sha256>;
+
+    let key_id = request.key;
+    let key = keystore.load_key(key::Secrecy::Secret, None, &key_id)?;
+    let shared_secret = key.material;
+
+    let mut mac =
+        HmacSha256P256::new_from_slice(shared_secret.as_ref()).map_err(|_| Error::InternalError)?;
+
+    if let Some(data) = &request.data {
+        mac.update(data);
+    }
+    let derived_key: [u8; 32] = mac
+        .finalize()
+        .into_bytes()
+        .try_into()
+        .map_err(|_| Error::InternalError)?;
+    let key_id = keystore.store_key(
+        request.location,
+        key::Secrecy::Secret,
+        key::Kind::P256, // TODO use mechanism/kind from the request
+        &derived_key,
+    )?;
+    Ok(reply::DeriveFromHash { key: Some(key_id) })
+}
+
+pub fn inject_any_key(
+    keystore: &mut impl Keystore,
+    request: &request::InjectAnyKey,
+) -> Result<reply::InjectAnyKey, Error> {
+    let key_id = keystore.store_key(
+        request.location,
+        key::Secrecy::Secret,
+        request.kind,
+        &request.raw_key,
+    )?;
+
+    Ok(reply::InjectAnyKey { key: Some(key_id) })
+}
+
+impl ExtensionImpl<HmacSha256P256Extension> for super::StagingBackend {
+    fn extension_request<P: trussed::Platform>(
+        &mut self,
+        core_ctx: &mut CoreContext,
+        _backend_ctx: &mut Self::Context,
+        request: &HmacSha256P256Request,
+        resources: &mut ServiceResources<P>,
+    ) -> Result<HmacSha256P256Reply, Error> {
+        let keystore = &mut resources.keystore(core_ctx)?;
+        match request {
+            HmacSha256P256Request::DeriveFromHash(request) => {
+                derive_key_from_hash(keystore, request).map(Into::into)
+            }
+            HmacSha256P256Request::InjectAnyKey(request) => {
+                inject_any_key(keystore, request).map(Into::into)
+            }
+        }
+    }
+}
+
+type HmacSha256P256Result<'a, R, C> = ExtensionResult<'a, HmacSha256P256Extension, R, C>;
+
+pub trait HmacSha256P256Client: ExtensionClient<HmacSha256P256Extension> {
+    fn derive_from_hash(
+        &mut self,
+        mechanism: Mechanism,
+        key: KeyId,
+        location: Location,
+        data: &[u8],
+    ) -> HmacSha256P256Result<'_, reply::DeriveFromHash, Self> {
+        let data = Bytes::from_slice(data).map_err(|_| ClientError::DataTooLarge)?;
+        self.extension(request::DeriveFromHash {
+            mechanism,
+            key,
+            location,
+            data: Some(data),
+        })
+    }
+
+    fn inject_any_key(
+        &mut self,
+        raw_key: SerializedKey,
+        location: Location,
+        kind: Kind,
+    ) -> HmacSha256P256Result<'_, reply::InjectAnyKey, Self> {
+        self.extension(request::InjectAnyKey {
+            location,
+            kind,
+            raw_key,
+        })
+    }
+}
+
+impl<C: ExtensionClient<HmacSha256P256Extension>> HmacSha256P256Client for C {}

src/lib.rs

@@ -18,6 +18,9 @@ pub mod wrap_key_to_file;
 #[cfg(feature = "chunked")]
 pub mod streaming;
 
+#[cfg(feature = "hmacsha256p256")]
+pub mod hmacsha256p256;
+
 #[derive(Clone, Debug, Default)]
 #[non_exhaustive]
 pub struct StagingBackend {}

tests/hmacsha256p256.rs

@@ -0,0 +1,38 @@
+// Copyright (C) Nitrokey GmbH
+// SPDX-License-Identifier: Apache-2.0 or MIT
+
+#![cfg(all(feature = "virt", feature = "hmacsha256p256"))]
+
+use trussed::client::CryptoClient;
+use trussed::key::Kind;
+use trussed::syscall;
+use trussed::types::{Location::*, Mechanism, SignatureSerialization};
+
+use trussed::types::Location;
+
+use trussed_staging::virt::with_ram_client;
+
+use trussed::client::P256;
+use trussed_staging::hmacsha256p256::HmacSha256P256Client;
+
+#[test]
+fn hmac_inject_any() {
+    with_ram_client("staging-tests", |mut client| {
+        let client = &mut client;
+
+        let key = syscall!(client.inject_any_key(
+            b"12345678123456781234567812345678",
+            Volatile,
+            Kind::P256
+        ))
+        .key
+        .unwrap();
+
+        let pk = syscall!(client.derive_p256_public_key(key, Location::Volatile)).key;
+
+        let signature =
+            syscall!(client.sign(Mechanism::P256, key, &[], SignatureSerialization::Raw)).signature;
+        assert!(signature.len() > 0);
+        todo!();
+    });
+}