# rhboot/shim

UEFI shim loader

Repository: https://github.com/rhboot/shim
Canonical: https://ross.abutalabs.com/products/shim
Language: C
License: NOASSERTION
License Family: other
Last push: 2026-07-27T18:18:30+00:00

## Health v2 (maintenance only)
Score: 69/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 94, release rhythm 18, longevity 100
- inputs: {"age_days": 5257, "days_push": 37, "days_rel": 385, "gap_med": 147, "n_releases_24m": 2}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1099, forks 349 (observed 2026-08-28T04:03:35.126346+00:00)

## What it is
shim is a small first-stage UEFI bootloader written in C that loads and validates a second-stage bootloader, enabling Secure Boot on Linux systems. It verifies binaries against built-in vendor certificates, supports denylists (DBX/MOKX/SBAT), and extends TPM PCRs with loaded target digests.

## Use cases
- boot linux with secure boot enabled
- chainload grub from uefi secure boot
- sign a custom bootloader for secure boot
- load unified kernel images with secure boot
- measure boot components into tpm pcrs

## When to choose
- you need to boot an unsigned or third-party bootloader while uefi secure boot is enabled
- you are building a linux distribution that must work with microsoft's secure boot signing
- you want tpm-based measured boot for disk encryption or attestation

## When to avoid
- your system does not use uefi (legacy bios boot)
- you do not need secure boot and can boot your bootloader directly
- you need a full boot manager rather than a first-stage loader

## Facets
- artifact type: library
- maturity: active
- function: security, cryptography
- domain: security, operating-systems, developer-tools
- platform: windows, cross-platform
- tags: uefi, secure-boot, bootloader, firmware, tpm, efi-application, linux

## Member repositories
- rhboot/shim (main) score 69

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:35.126346+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:46:04.834790+00:00, confidence not recorded.
  - readme: https://github.com/rhboot/shim (fetched 2026-08-28T04:03:35.126346+00:00, sha 20a7fca83bde)
- Data as of 2026-08-30T08:39:29.467469+00:00.