eBoot — Secure Bootloader

eBoot (CMake project eBootloader) is a multi-platform, modular secure bootloader written in C. It is organized as a two-stage boot chain: a minimal Stage-0 that performs early hardware bring-up, and a Stage-1 that scans, selects, verifies, and jumps to an application or RTOS image. Image authentication uses Ed25519 signatures, with A/B slot management, recovery, and firmware-update transports built into the core.

eBoot is the boot component of the EmbeddedOS (embeddedos-org) ecosystem, providing verified boot for EoS and other payloads. Project version 3.0.2.

What's inside

Path	Contents
stage0/	Minimal early boot: reset entry, hardware init, watchdog, recovery entry, jump to Stage-1
stage1/	Boot logic: scan, select, boot log, jump to app (main.c)
core/	Platform-agnostic boot logic — Ed25519 verify, image TLV/verify, slot manager, secure/RTOS boot, keystore, anti-rollback counter, firmware update/decrypt, UART transport, boot policy/menu, recovery — builds eboot_core
hal/	HAL dispatch and board registry — builds eboot_hal
include/	Public headers (eos_secure_boot.h, eos_image.h, eos_slot_manager.h, eos_keystore.h, …)
boards/	Per-architecture board support (83 board directories)
configs/	Boot/flash/image YAML schemas and flash-tool config
toolchains/	Cross-compile toolchain files (aarch64, arm-none-eabi, riscv64, …)
tests/	unit/, functional/, fuzz/, performance/, simulation/

Build

Requires CMake ≥ 3.15 and a C compiler. A native build (no board selected) compiles the platform-agnostic core libraries and, with tests enabled, the test suite — these contain no architecture-specific code and build on Linux, macOS, and Windows.

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --parallel

Cross-compile for a target board with EBLDR_BOARD and a toolchain file:

cmake -B build/stm32 \
  -DEBLDR_BOARD=stm32f4 \
  -DCMAKE_TOOLCHAIN_FILE=toolchains/arm-none-eabi.cmake
cmake --build build/stm32 --parallel

EBLDR_BOARD accepts stm32f4, stm32h7, nrf52, rpi4, riscv64_virt, esp32, x86_64_efi, imx8m, am64x, samd51, sifive_u, cortex_r5, and others (default none = native core-only build).

Security options

Option	Default	Meaning
EBLDR_REQUIRE_SIGNATURES	ON	Require Ed25519 signatures for boot
EBLDR_VERIFY_STAGE1	ON	Verify the Stage-1 hash before jumping
EBLDR_RECOVERY_AUTH	ON	Require authentication for recovery commands
EBLDR_HARDENING	ON	Compiler hardening (-fstack-protector-strong, _FORTIFY_SOURCE=2)
EBLDR_SANITIZE	OFF	ASan/UBSan for host builds
EBLDR_BUILD_FUZZ	OFF	Build libFuzzer targets
EBLDR_BUILD_TESTS	OFF	Build unit tests (native only)

Test

cmake -B build -DEBLDR_BUILD_TESTS=ON
cmake --build build --parallel
ctest --test-dir build --output-on-failure

# Python-driven suites
python run_all_tests.py

Docs

See docs/: quickstart.md, architecture.md, secure_boot_chain.md, key_lifecycle.md, threat_model.md, memory-map.md, update-flow.md, and the security_review_checklist.md.

License

Licensed under the MIT License.