lib-fs-crypto

lib-fs-crypto contains allocation-free no_std helpers for filesystem encryption and verity plumbing. It parses Linux fscrypt v1/v2 on-disk contexts, applies the currently EriX-specific fscrypt-v2-style key derivation, transforms full AES-XTS data units and padded AES-CTS filenames, parses Linux fsverity descriptors, computes Linux-shaped SHA-256 Merkle roots, and performs constant-work trusted-root comparisons. Its optional-signature inspection validates only the outer DER sequence and PKCS#7 SignedData object identifier; EriX does not parse or verify PKCS#7 signatures.

EriX is a clean-room, capability-based microkernel operating system written entirely in Rust.

Technical requirements are tracked in the EriX requirements, conventions, and project documentation.

See:

• docs for design documents, specifications, and development plans.
• Related architecture repositories for kernel, services, libraries, drivers, and integration tooling.

Purpose of This Repository

This repository implements the EriX filesystem crypto library. Its purpose in EriX is to provide reusable filesystem crypto primitives and contracts to EriX components.

Functionally, it exposes the filesystem crypto APIs, validation tests, and documentation used by dependent repositories. The repository keeps the implementation, interface contracts, tests, and documentation for that behavior in one reviewable ownership boundary.

The maintained responsibilities are:

• expose the lib-fs-crypto crate API for filesystem crypto behavior used by dependent components
• keep data formats, constants, and validation helpers documented and tested
• preserve clean-room, no-external-crate implementation boundaries
• coordinate intentional pre-1.0 API changes with e2fsd
• expose no runtime key storage or lookup authority; callers such as e2fsd must obtain key material through their own explicit authority

Clean-Room Policy

EriX follows a strict clean-room philosophy:

• No external source code may be copied.
• No external Rust crates are allowed.
• No code generation tools that embed third-party code.
• All code must be authored within the project.

Violations will result in rejection of the contribution.

License

All EriX repositories are licensed under the ISC License.

Development Model

EriX development is modular, deterministic, reproducible, authority-explicit, security-first, and self-hosting oriented.

This repository follows the project roadmap and the validation rules documented in its own roadmap.

Validation

cargo fmt --all -- --check
RUSTFLAGS="-D warnings" cargo clippy --all-targets --all-features -- -D warnings
RUSTFLAGS="-D warnings" cargo test --all-targets --all-features

Governance Principles

lib-fs-crypto governance is scoped to reusable filesystem crypto contracts shared by dependent repositories.

The scoped governance rules are:

• It must expose narrow, documented APIs rather than component-specific policy.
• It keeps wire formats, constants, parsers, and validation helpers deterministic and testable.
• It preserves clean-room implementation boundaries and does not introduce external crate dependencies.
• Breaking API or format changes require coordinated updates in every dependent repository.

Library Boundaries

• lib-fs-crypto carries no runtime authority by itself; authority is held by callers that use the library.
• The crate must not hide ambient I/O, allocation policy, or service discovery behind helper APIs.

Contact

Development occurs in EriX organization and discussions happen in issues and design documents.

No decisions are considered valid without documented rationale.

Maintainers can be reached via email: admin@erikinkinen.fi.