lib-ed25519

Minimal no_std Ed25519 verification crate for EriX secure boot and related validation paths.

This crate is verification-focused. It provides signature verification primitives for public-key validation in boot-critical code.

UEFI + x86_64 are current primary targets, but this crate is explicitly portable and architecture-neutral.

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Scope

This crate provides:

• Ed25519 public key and signature types
• strict decode/validation helpers for key/signature inputs
• Ed25519 signature verification for message bytes

This crate does not provide:

• private-key operations or signing
• key generation
• random number generation
• certificate chain parsing

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Why this crate exists

EriX boot verification requires a small, auditable implementation for Ed25519 verification with no external dependencies.

Keeping this functionality in a dedicated crate improves:

• auditability of TCB code
• reuse across lib-bootimg, bootloader, and kernel-side validators
• deterministic behavior across supported targets

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Design constraints

• #![no_std]
• zero external dependencies
• deterministic, explicit error handling
• constant-time treatment in security-relevant comparisons
• minimal and documented unsafe (ideally none)

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Security notes

This crate is part of a security boundary when used in secure boot.

Invalid encodings or malformed inputs must be rejected strictly. Verification must be fail-closed.

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Intended consumers

• lib-bootimg verification flow
• bootloader signature verification path
• future kernel/user-space signature checks

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Status

Implemented baseline.

Strict parsing/validation and verification APIs are implemented with unit coverage. Remaining work is hardening and broader integration fixture coverage.

See ARCHITECTURE.md and ROADMAP.md.