Import HkdfExtension from Nitrokey/trussed-hkdf-backend

The HkdfExtension was previously maintained in a separate repository and
together with a custom backend.  Every additional backend adds some
overhead, both in the firmware and for maintenance.  Therefore this
patch moves the trussed-hkdf crate with the HkdfExtension as an
extension into this repository and implements it for the StagingBackend,
replacing the HkdfBackend.

This patch also releases trussed-hkdf v0.2.0 and trussed-staging v0.3.0.

Fixes: Nitrokey/trussed-hkdf-backend#6

CHANGELOG.md

@@ -11,9 +11,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased][]
 
+[Unreleased]: https://github.com/trussed-dev/trussed-staging/compare/v0.3.0...HEAD
+
+-
+
+## [0.3.0][] - 2024-03-25
+
+[0.3.0]: https://github.com/trussed-dev/trussed-staging/compare/v0.2.0...v0.3.0
+
 - Remove `manage` from default features.
+- Implement `HkdfExtension` (moved from [Nitrokey/trussed-hkdf-backend][])
 
-[Unreleased]: https://github.com/trussed-dev/trussed-staging/compare/v0.2.0...HEAD
+[Nitrokey/trussed-hkdf-backend]: https://github.com/Nitrokey/trussed-hkdf-backend
 
 ## [0.2.0][] - 2024-03-15
 

Cargo.toml

@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: CC0-1.0
 
 [workspace]
-members = ["extensions/chunked", "extensions/manage", "extensions/wrap-key-to-file"]
+members = ["extensions/chunked", "extensions/hkdf", "extensions/manage", "extensions/wrap-key-to-file"]
 
 [workspace.package]
 authors = ["Nitrokey GmbH <[email protected]>"]
@@ -17,7 +17,7 @@ trussed = { version = "0.1.0", features = ["serde-extensions"] }
 
 [package]
 name = "trussed-staging"
-version = "0.2.0"
+version = "0.3.0"
 description = "Work in progress trussed features"
 authors.workspace = true
 edition.workspace = true
@@ -30,23 +30,29 @@ serde-byte-array.workspace = true
 trussed.workspace = true
 
 chacha20poly1305 = { version = "0.10", default-features = false, features = ["heapless", "reduced-round"], optional = true }
-rand_core = { version = "0.6.4", default-features = false }
 delog = "0.1.6"
+hkdf = { version = "0.12", optional = true }
+rand_core = { version = "0.6.4", default-features = false }
+sha2 = { version = "0.10", default-features = false, optional = true }
 littlefs2 = "0.4.0"
 
 trussed-chunked = { version = "0.1.0", optional = true }
+trussed-hkdf = { version = "0.2.0", optional = true }
 trussed-manage = { version = "0.1.0", optional = true }
 trussed-wrap-key-to-file = { version = "0.1.0", optional = true }
 
 [dev-dependencies]
+hex-literal = "0.3.4"
+hmac = "0.12.0"
 trussed = { workspace = true, features = ["virt"] }
 
 [features]
 default = []
 
-wrap-key-to-file = ["chacha20poly1305", "trussed-wrap-key-to-file"]
 chunked = ["trussed-chunked", "chacha20poly1305/stream"]
+hkdf = ["trussed-hkdf", "dep:hkdf", "dep:sha2"]
 manage = ["trussed-manage"]
+wrap-key-to-file = ["chacha20poly1305", "trussed-wrap-key-to-file"]
 
 virt = ["std", "trussed/virt"]
 std = []
@@ -64,5 +70,6 @@ trussed = { git = "https://github.com/trussed-dev/trussed.git", rev = "45ed62ba9
 littlefs2 = { git = "https://github.com/trussed-dev/littlefs2.git", rev = "ebd27e49ca321089d01d8c9b169c4aeb58ceeeca" }
 
 trussed-chunked = { path = "extensions/chunked" }
+trussed-hkdf = { path = "extensions/hkdf" }
 trussed-manage = { path = "extensions/manage" }
 trussed-wrap-key-to-file = { path = "extensions/wrap-key-to-file" }

Makefile

@@ -6,6 +6,7 @@ check:
 	RUSTLFAGS='-Dwarnings' cargo check --all-features --all-targets --workspace
 	RUSTLFAGS='-Dwarnings' cargo check --no-default-features
 	RUSTLFAGS='-Dwarnings' cargo check --features chunked
+	RUSTLFAGS='-Dwarnings' cargo check --features hkdf
 	RUSTLFAGS='-Dwarnings' cargo check --features manage
 	RUSTLFAGS='-Dwarnings' cargo check --features wrap-key-to-file
 

extensions/hkdf/CHANGELOG.md

@@ -0,0 +1,34 @@
+<!--
+Copyright (C) Nitrokey GmbH
+SPDX-License-Identifier: CC0-1.0
+-->
+
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased][]
+
+[Unreleased]: https://github.com/trussed-dev/trussed-staging/compare/hkdf-v0.2.0...HEAD
+
+-
+
+## [0.2.0][] - 2024-03-25
+
+[0.2.0]: https://github.com/trussed-dev/trussed-staging/releases/tag/hkdf-v0.2.0
+
+- Move the `trussed-hkdf` crate from the [Nitrokey/trussed-hkdf-backend][]
+  repository into the [trussed-dev/trussed-staging][] repository
+- Remove the `HkdfBackend`.  The `HkdfExtension` is now implemented by the
+  `StagingBackend` in `trussed-staging` if the `hkdf` feature is enabled
+
+[Nitrokey/trussed-hkdf-backend]: https://github.com/Nitrokey/trussed-hkdf-backend
+[trussed-dev/trussed-staging]: https://github.com/trussed-dev/trussed-staging
+
+## [0.1.0][] - 2024-02-20
+
+[0.1.0]: https://github.com/Nitrokey/trussed-hkdf-backend/releases/tag/v0.1.0
+
+Initial release of the `HkdfExtension` and its implementation in the `HkdfBackend`.

extensions/hkdf/Cargo.toml

@@ -0,0 +1,14 @@
+# Copyright (C) Nitrokey GmbH
+# SPDX-License-Identifier: CC0-1.0
+
+[package]
+name = "trussed-hkdf"
+version = "0.2.0"
+authors.workspace = true
+edition.workspace = true
+repository.workspace = true
+license.workspace = true
+
+[dependencies]
+serde.workspace = true
+trussed.workspace = true

extensions/hkdf/src/lib.rs

@@ -0,0 +1,164 @@
+// Copyright (C) Nitrokey GmbH
+// SPDX-License-Identifier: Apache-2.0 or MIT
+
+#![no_std]
+#![warn(non_ascii_idents, trivial_casts, unused, unused_qualifications)]
+#![deny(unsafe_code)]
+
+use serde::{Deserialize, Serialize};
+use trussed::{
+    config::MAX_MEDIUM_DATA_LENGTH,
+    serde_extensions::{Extension, ExtensionClient, ExtensionResult},
+    types::{Bytes, KeyId, Location, Message},
+    Error,
+};
+
+#[derive(Clone, Copy, Debug, Serialize, Deserialize)]
+pub struct OkmId(pub KeyId);
+
+/// Can represent either data or a key
+#[derive(Serialize, Deserialize)]
+pub enum KeyOrData<const N: usize> {
+    Key(KeyId),
+    Data(Bytes<N>),
+}
+
+pub struct HkdfExtension;
+
+impl Extension for HkdfExtension {
+    type Request = HkdfRequest;
+    type Reply = HkdfReply;
+}
+
+#[allow(clippy::large_enum_variant)]
+#[derive(Serialize, Deserialize)]
+pub enum HkdfRequest {
+    Extract(HkdfExtractRequest),
+    Expand(HkdfExpandRequest),
+}
+#[derive(Serialize, Deserialize)]
+pub enum HkdfReply {
+    Extract(HkdfExtractReply),
+    Expand(HkdfExpandReply),
+}
+
+impl From<HkdfExpandRequest> for HkdfRequest {
+    fn from(v: HkdfExpandRequest) -> Self {
+        Self::Expand(v)
+    }
+}
+
+impl From<HkdfExtractRequest> for HkdfRequest {
+    fn from(v: HkdfExtractRequest) -> Self {
+        Self::Extract(v)
+    }
+}
+
+impl From<HkdfExpandReply> for HkdfReply {
+    fn from(v: HkdfExpandReply) -> Self {
+        Self::Expand(v)
+    }
+}
+
+impl From<HkdfExtractReply> for HkdfReply {
+    fn from(v: HkdfExtractReply) -> Self {
+        Self::Extract(v)
+    }
+}
+
+impl TryFrom<HkdfRequest> for HkdfExpandRequest {
+    type Error = Error;
+    fn try_from(v: HkdfRequest) -> Result<Self, Error> {
+        match v {
+            HkdfRequest::Expand(v) => Ok(v),
+            _ => Err(Error::InternalError),
+        }
+    }
+}
+impl TryFrom<HkdfRequest> for HkdfExtractRequest {
+    type Error = Error;
+    fn try_from(v: HkdfRequest) -> Result<Self, Error> {
+        match v {
+            HkdfRequest::Extract(v) => Ok(v),
+            _ => Err(Error::InternalError),
+        }
+    }
+}
+
+impl TryFrom<HkdfReply> for HkdfExpandReply {
+    type Error = Error;
+    fn try_from(v: HkdfReply) -> Result<Self, Error> {
+        match v {
+            HkdfReply::Expand(v) => Ok(v),
+            _ => Err(Error::InternalError),
+        }
+    }
+}
+impl TryFrom<HkdfReply> for HkdfExtractReply {
+    type Error = Error;
+    fn try_from(v: HkdfReply) -> Result<Self, Error> {
+        match v {
+            HkdfReply::Extract(v) => Ok(v),
+            _ => Err(Error::InternalError),
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct HkdfExtractReply {
+    pub okm: OkmId,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct HkdfExtractRequest {
+    pub ikm: KeyOrData<MAX_MEDIUM_DATA_LENGTH>,
+    pub salt: Option<KeyOrData<MAX_MEDIUM_DATA_LENGTH>>,
+    /// Location to store the OKM
+    pub storage: Location,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct HkdfExpandReply {
+    pub key: KeyId,
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct HkdfExpandRequest {
+    pub prk: OkmId,
+    pub info: Message,
+    pub len: usize,
+    pub storage: Location,
+}
+
+pub type HkdfResult<'a, R, C> = ExtensionResult<'a, HkdfExtension, R, C>;
+
+pub trait HkdfClient: ExtensionClient<HkdfExtension> {
+    fn hkdf_extract(
+        &mut self,
+        ikm: KeyOrData<MAX_MEDIUM_DATA_LENGTH>,
+        salt: Option<KeyOrData<MAX_MEDIUM_DATA_LENGTH>>,
+        storage: Location,
+    ) -> HkdfResult<'_, HkdfExtractReply, Self> {
+        self.extension(HkdfRequest::Extract(HkdfExtractRequest {
+            ikm,
+            salt,
+            storage,
+        }))
+    }
+    fn hkdf_expand(
+        &mut self,
+        prk: OkmId,
+        info: Message,
+        len: usize,
+        storage: Location,
+    ) -> HkdfResult<'_, HkdfExpandReply, Self> {
+        self.extension(HkdfRequest::Expand(HkdfExpandRequest {
+            prk,
+            info,
+            len,
+            storage,
+        }))
+    }
+}
+
+impl<C: ExtensionClient<HkdfExtension>> HkdfClient for C {}