RS-Key

Projects that follow the best practices below can voluntarily self-certify and show that they've achieved an Open Source Security Foundation (OpenSSF) best practices badge.

There is no set of practices that can guarantee that software will never have defects or vulnerabilities; even formal methods can fail if the specifications or assumptions are wrong. Nor is there any set of practices that can guarantee that a project will sustain a healthy and well-functioning development community. However, following best practices can help improve the results of projects. For example, some practices enable multi-person review before release, which can both help find otherwise hard-to-find technical vulnerabilities and help build trust and a desire for repeated interaction among developers from different companies. To earn a badge, all MUST and MUST NOT criteria must be met, all SHOULD criteria must be met OR be unmet with justification, and all SUGGESTED criteria must be met OR unmet (we want them considered at least). If you want to enter justification text as a generic comment, instead of being a rationale that the situation is acceptable, start the text block with '//' followed by a space. Feedback is welcome via the GitHub site as issues or pull requests There is also a mailing list for general discussion.

We gladly provide the information in several locales, however, if there is any conflict or inconsistency between the translations, the English version is the authoritative version.
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These are the Silver level criteria. You can also view the Passing or Gold level criteria.

Baseline Series: Baseline Level 1 Baseline Level 2 Baseline Level 3

        

 Basics 17/17 ●

  • General

    Note that other projects may use the same name.

    Turn a $5 Raspberry Pi RP2350 board into an open-source hardware passkey: WebAuthn/FIDO2 logins, ssh & git signing, OpenPGP, PIV, TOTP. Rust firmware, no_std.

    Please use SPDX license expression format; examples include "Apache-2.0", "BSD-2-Clause", "BSD-3-Clause", "GPL-2.0+", "LGPL-3.0+", "MIT", and "(BSD-2-Clause OR Ruby)". Do not include single quotes or double quotes.
    If there is more than one language, list them as comma-separated values (spaces optional) and sort them from most to least used. If there is a long list, please list at least the first three most common ones. If there is no language (e.g., this is a documentation-only or test-only project), use the single character "-". Please use a conventional capitalization for each language, e.g., "JavaScript".
    The Common Platform Enumeration (CPE) is a structured naming scheme for information technology systems, software, and packages. It is used in a number of systems and databases when reporting vulnerabilities.

  • Prerequisites


    Enough for a badge!

    The project MUST achieve a passing level badge. [achieve_passing]

  • Basic project website content


    Enough for a badge!

    The information on how to contribute MUST include the requirements for acceptable contributions (e.g., a reference to any required coding standard). (URL required) [contribution_requirements]

    https://github.com/TheMaxMur/RS-Key/blob/main/CONTRIBUTING.md


  • Project oversight


    Enough for a badge!

    The project SHOULD have a legal mechanism where all developers of non-trivial amounts of project software assert that they are legally authorized to make these contributions. The most common and easily-implemented approach for doing this is by using a Developer Certificate of Origin (DCO), where users add "signed-off-by" in their commits and the project links to the DCO website. However, this MAY be implemented as a Contributor License Agreement (CLA), or other legal mechanism. (URL required) [dco]
    The DCO is the recommended mechanism because it's easy to implement, tracked in the source code, and git directly supports a "signed-off" feature using "commit -s". To be most effective it is best if the project documentation explains what "signed-off" means for that project. A CLA is a legal agreement that defines the terms under which intellectual works have been licensed to an organization or project. A contributor assignment agreement (CAA) is a legal agreement that transfers rights in an intellectual work to another party; projects are not required to have CAAs, since having CAA increases the risk that potential contributors will not contribute, especially if the receiver is a for-profit organization. The Apache Software Foundation CLAs (the individual contributor license and the corporate CLA) are examples of CLAs, for projects which determine that the risks of these kinds of CLAs to the project are less than their benefits.

    The project has no DCO or CLA. Contribution is governed by the AGPL-3.0-only
    header every file carries and by CONTRIBUTING.md, which states that by
    contributing you license your work under it. For a single-maintainer hobby
    project a sign-off ceremony would add process without adding assurance; this may
    change if the contributor base grows.
    https://github.com/TheMaxMur/RS-Key/blob/main/CONTRIBUTING.md


    Enough for a badge!

    The project MUST clearly define and document its project governance model (the way it makes decisions, including key roles). (URL required) [governance]
    There needs to be some well-established documented way to make decisions and resolve disputes. In small projects, this may be as simple as "the project owner and lead makes all final decisions". There are various governance models, including benevolent dictator and formal meritocracy; for more details, see Governance models. Both centralized (e.g., single-maintainer) and decentralized (e.g., group maintainers) approaches have been successfully used in projects. The governance information does not need to document the possibility of creating a project fork, since that is always possible for FLOSS projects.

    GOVERNANCE.md documents the model: the gate decides correctness, the maintainer
    decides scope and trade-offs, disagreement is settled by evidence first and the
    maintainer second, and the AGPL is the only appeal. It also lists what is
    maintainer-only (signing, OTP fuses, pushing, toolchain pins) and how the
    document itself is amended.
    https://github.com/TheMaxMur/RS-Key/blob/main/GOVERNANCE.md


    Enough for a badge!

    The project MUST adopt a code of conduct and post it in a standard location. (URL required) [code_of_conduct]
    Projects may be able to improve the civility of their community and to set expectations about acceptable conduct by adopting a code of conduct. This can help avoid problems before they occur and make the project a more welcoming place to encourage contributions. This should focus only on behavior within the community/workplace of the project. Example codes of conduct are the Linux kernel code of conduct, the Contributor Covenant Code of Conduct, the Debian Code of Conduct, the Ubuntu Code of Conduct, the Fedora Code of Conduct, the GNOME Code Of Conduct, the KDE Community Code of Conduct, the Python Community Code of Conduct, The Ruby Community Conduct Guideline, and The Rust Code of Conduct.

    Contributor Covenant 2.1, adopted verbatim, in the standard repository location.
    Enforcement contact is the maintainer on GitHub.
    https://github.com/TheMaxMur/RS-Key/blob/main/CODE_OF_CONDUCT.md


    Enough for a badge!

    The project MUST clearly define and publicly document the key roles in the project and their responsibilities, including any tasks those roles must perform. It MUST be clear who has which role(s), though this might not be documented in the same way. (URL required) [roles_responsibilities]
    The documentation for governance and roles and responsibilities may be in one place.

    GOVERNANCE.md defines three roles and what each one does: maintainer (review and
    merge, triage, releases, and the irreversible operations nobody else performs),
    contributor (owns their diff, green gate before review), and reporter (private
    vulnerability reports, credited unless they decline). It states explicitly that
    there is no separate reviewer or committer role, and what the path to becoming a
    maintainer is.
    https://github.com/TheMaxMur/RS-Key/blob/main/GOVERNANCE.md#roles


    Enough for a badge!

    The project MUST be able to continue with minimal interruption if any one person dies, is incapacitated, or is otherwise unable or unwilling to continue support of the project. In particular, the project MUST be able to create and close issues, accept proposed changes, and release versions of software, within a week of confirmation of the loss of support from any one individual. This MAY be done by ensuring someone else has any necessary keys, passwords, and legal rights to continue the project. Individuals who run a FLOSS project MAY do this by providing keys in a lockbox and a will providing any needed legal rights (e.g., for DNS names). (URL required) [access_continuity]

    A second person holds write access to the repository and can merge pull
    requests, triage and close issues, and tag and publish a release from day one —
    the three abilities this criterion names — with no legal process or password
    handover in between. Write rather than admin is deliberate: enough to continue
    the project, not enough to take it over. The admin-only functions (settings,
    granting access, the private security advisories) stay with the maintainer and
    pass with the estate, and GOVERNANCE.md states that cost rather than hiding it.
    No key escrow is required: the secure-boot signing key is held by each board's
    owner, the MKEK/DEVK are generated on-device and forgotten, and releases are
    signed keyless through the repository's own workflow identity, so repository
    access is the entire single-homed surface.
    https://github.com/TheMaxMur/RS-Key/blob/main/GOVERNANCE.md#continuity


    Barely enough for a badge.

    The project SHOULD have a "bus factor" of 2 or more. (URL required) [bus_factor]
    A "bus factor" (aka "truck factor") is the minimum number of project members that have to suddenly disappear from a project ("hit by a bus") before the project stalls due to lack of knowledgeable or competent personnel. The truck-factor tool can estimate this for projects on GitHub. For more information, see Assessing the Bus Factor of Git Repositories by Cosentino et al.

    One. The truck-factor tool this criterion links to (aserg-ufmg/Truck-Factor,
    Avelino et al., ICPC 2016), run against the repository on 2026-09-21, reports
    TF = 1 with a residual coverage of 3.08%: one developer is the DOA author of
    1542 of 1558 files. A second person with write access restores the ability to
    act — merge, triage, release — but not the accumulated context, and GOVERNANCE.md
    says so rather than claiming otherwise. The mitigation is written rather than
    human: the threat model, the formal models, the assurance case and a merge gate
    that encodes the bar exist so a successor can tell what the project promised and
    check whether a change still keeps it.
    https://github.com/TheMaxMur/RS-Key/blob/main/GOVERNANCE.md#continuity


  • Documentation


    Enough for a badge!

    The project MUST have a documented roadmap that describes what the project intends to do and not do for at least the next year. (URL required) [documentation_roadmap]
    The project might not achieve the roadmap, and that's fine; the purpose of the roadmap is to help potential users and contributors understand the intended direction of the project. It need not be detailed.

    A published roadmap of directions (not dates — a schedule from one maintainer
    would be a promise nobody can keep) with an explicit list of what the project
    will not do. https://themaxmur.github.io/RS-Key/roadmap.html


    Enough for a badge!

    The project MUST include documentation of the architecture (aka high-level design) of the software produced by the project. If the project does not produce software, select "not applicable" (N/A). (URL required) [documentation_architecture]
    A software architecture explains a program's fundamental structures, i.e., the program's major components, the relationships among them, and the key properties of these components and relationships.

    Architecture page: the two-executor design, the boot sequence, the crate graph
    (generated and gated, not drawn by hand), the flash layout and device identity.
    https://themaxmur.github.io/RS-Key/architecture.html


    Enough for a badge!

    The project MUST document what the user can and cannot expect in terms of security from the software produced by the project (its "security requirements"). (URL required) [documentation_security]
    These are the security requirements that the software is intended to meet.

    The threat model states what is defended against, what is deliberately out of
    scope (physical and lab attacks — the RP2350 is not a secure element) and the
    residuals in between; the limitations page is the companion list of what the
    project does not do and why.
    https://themaxmur.github.io/RS-Key/threat-model.html


    Enough for a badge!

    The project MUST provide a "quick start" guide for new users to help them quickly do something with the software. (URL required) [documentation_quick_start]
    The idea is to show users how to get started and make the software do anything at all. This is critically important for potential users to get started.

    From a fresh board to a passkey login with nothing to build — a web flasher or a
    single .uf2 drag-drop. https://themaxmur.github.io/RS-Key/quickstart.html


    Enough for a badge!

    The project MUST make an effort to keep the documentation consistent with the current version of the project results (including software produced by the project). Any known documentation defects making it inconsistent MUST be fixed. If the documentation is generally current, but erroneously includes some older information that is no longer true, just treat that as a defect, then track and fix as usual. [documentation_current]
    The documentation MAY include information about differences or changes between versions of the software and/or link to older versions of the documentation. The intent of this criterion is that an effort is made to keep the documentation consistent, not that the documentation must be perfect.

    Documentation is gated, not merely intended: scripts/docs.sh check builds the
    site and link-checks it, scripts/docs_constants.py fails the build when a value
    stated in the docs no longer matches the constant in the code, and a citation
    gate holds the model pages to the code lines they cite. A protocol-visible change
    must update docs/protocol.md and the matching guide in the same change.


    Enough for a badge!

    The project repository front page and/or website MUST identify and hyperlink to any achievements, including this best practices badge, within 48 hours of public recognition that the achievement has been attained. (URL required) [documentation_achievements]
    An achievement is any set of external criteria that the project has specifically worked to meet, including some badges. This information does not need to be on the project website front page. A project using GitHub can put achievements on the repository front page by adding them to the README file.

    The OpenSSF best practices badge is linked from the repository front page,
    alongside the CI badges. https://github.com/TheMaxMur/RS-Key#readme


  • Accessibility and internationalization


    Enough for a badge!

    The project (both project sites and project results) SHOULD follow accessibility best practices so that persons with disabilities can still participate in the project and use the project results where it is reasonable to do so. [accessibility_best_practices]
    For web applications, see the Web Content Accessibility Guidelines (WCAG 2.0) and its supporting document Understanding WCAG 2.0; see also W3C accessibility information. For GUI applications, consider using the environment-specific accessibility guidelines (such as Gnome, KDE, XFCE, Android, iOS, Mac, and Windows). Some TUI applications (e.g. `ncurses` programs) can do certain things to make themselves more accessible (such as `alpine`'s `force-arrow-cursor` setting). Most command-line applications are fairly accessible as-is. This criterion is often N/A, e.g., for program libraries. Here are some examples of actions to take or issues to consider:
    • Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language ( WCAG 2.0 guideline 1.1)
    • Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. ( WCAG 2.0 guideline 1.4.1)
    • The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for large text, incidental text, and logotypes ( WCAG 2.0 guideline 1.4.3)
    • Make all functionality available from a keyboard (WCAG guideline 2.1)
    • A GUI or web-based project SHOULD test with at least one screen-reader on the target platform(s) (e.g. NVDA, Jaws, or WindowEyes on Windows; VoiceOver on Mac & iOS; Orca on Linux/BSD; TalkBack on Android). TUI programs MAY work to reduce overdraw to prevent redundant reading by screen-readers.

    The project site is a plain mdBook — semantic HTML, keyboard-navigable, readable without JavaScript for the prose. Every architecture and threat-model diagram carries a full descriptive alt text that states what the diagram shows rather than naming it, so the pages are usable by a screen reader. The device's own interface is a physical button, an LED and, on display builds, a high-contrast screen.


    Enough for a badge!

    The software produced by the project SHOULD be internationalized to enable easy localization for the target audience's culture, region, or language. If internationalization (i18n) does not apply (e.g., the software doesn't generate text intended for end-users and doesn't sort human-readable text), select "not applicable" (N/A). [internationalization]
    Localization "refers to the adaptation of a product, application or document content to meet the language, cultural and other requirements of a specific target market (a locale)." Internationalization is the "design and development of a product, application or document content that enables easy localization for target audiences that vary in culture, region, or language." (See W3C's "Localization vs. Internationalization".) Software meets this criterion simply by being internationalized. No localization for another specific language is required, since once software has been internationalized it's possible for others to work on localization.

    Not applicable. The device's user-visible text is a handful of short status strings rendered on a 1-bit embedded display from a compiled-in font atlas; there is no runtime locale, no string catalogue and no room in flash for one. The protocols it speaks (CTAP, PIV, OpenPGP card, OATH) are byte protocols, and the host tooling and documentation are English.


  • Other


    Enough for a badge!

    If the project sites (website, repository, and download URLs) store passwords for authentication of external users, the passwords MUST be stored as iterated hashes with a per-user salt by using a key stretching (iterated) algorithm (e.g., Argon2id, Bcrypt, Scrypt, or PBKDF2). If the project sites do not store passwords for this purpose, select "not applicable" (N/A). [sites_password_security]
    Note that the use of GitHub meets this criterion. This criterion only applies to passwords used for authentication of external users into the project sites (aka inbound authentication). If the project sites must log in to other sites (aka outbound authentication), they may need to store authorization tokens for that purpose differently (since storing a hash would be useless). This applies criterion crypto_password_storage to the project sites, similar to sites_https.

    The project sites store no passwords: the repository is GitHub and the documentation site is GitHub Pages. The project runs no authentication of its own.


 Change Control 1/1 ●

  • Previous versions


    Enough for a badge!

    The project MUST maintain the most often used older versions of the product or provide an upgrade path to newer versions. If the upgrade path is difficult, the project MUST document how to perform the upgrade (e.g., the interfaces that have changed and detailed suggested steps to help upgrade). [maintenance_or_update]

    The upgrade path is the product: flashing the newest release replaces the firmware in place, and an already-provisioned device keeps its credentials across the upgrade — a persistent-format change must load older record layouts forward and say how. The one case where that does not hold is documented at the top of the CHANGELOG with the export step to take first. There are no maintained release branches, stated in SECURITY.md; supported means the tip of main.


 Reporting 3/3 ●

  • Bug-reporting process


    Enough for a badge!

    The project MUST use an issue tracker for tracking individual issues. [report_tracker]

    GitHub Issues, with issue templates:
    https://github.com/TheMaxMur/RS-Key/issues


  • Vulnerability report process


    Enough for a badge!

    The project MUST give credit to the reporter(s) of all vulnerability reports resolved in the last 12 months, except for the reporter(s) who request anonymity. If there have been no vulnerabilities resolved in the last 12 months, select "not applicable" (N/A). (URL required) [vulnerability_report_credit]

    No externally reported vulnerability has been resolved in the last 12 months, so
    there is nobody yet to credit. SECURITY.md invites private reports and treats the
    reporter's name as theirs to give or withhold.
    https://github.com/TheMaxMur/RS-Key/blob/main/SECURITY.md


    Enough for a badge!

    The project MUST have a documented process for responding to vulnerability reports. (URL required) [vulnerability_response_process]
    This is strongly related to vulnerability_report_process, which requires that there be a documented way to report vulnerabilities. It also related to vulnerability_report_response, which requires response to vulnerability reports within a certain time frame.

    SECURITY.md documents the whole path: report privately through GitHub's private
    vulnerability reporting, what counts as a vulnerability here and what the threat
    model already concedes, what a good report contains, what to expect (an
    acknowledgment within a few days from one maintainer, a fix on main as fast as
    severity warrants), and which versions are supported.
    https://github.com/TheMaxMur/RS-Key/blob/main/SECURITY.md


 Quality 19/19 ●

  • Coding standards


    Enough for a badge!

    The project MUST identify the specific coding style guides for the primary languages it uses, and require that contributions generally comply with it. (URL required) [coding_standards]
    In most cases this is done by referring to some existing style guide(s), possibly listing differences. These style guides can include ways to improve readability and ways to reduce the likelihood of defects (including vulnerabilities). Many programming languages have one or more widely-used style guides. Examples of style guides include Google's style guides and SEI CERT Coding Standards.

    CONTRIBUTING.md and AGENTS.md state the standards contributions must meet:
    rustfmt formatting, clippy with -D warnings, no_std and no allocator in firmware
    crates, unsafe only with an entry in docs/unsafe.md, an SPDX header on every
    file, comments that explain constraints rather than mechanics with a three-line
    ceiling, no magic values, typed state instead of string matching, and the Python
    conventions for the host CLI.
    https://github.com/TheMaxMur/RS-Key/blob/main/CONTRIBUTING.md


    Enough for a badge!

    The project MUST automatically enforce its selected coding style(s) if there is at least one FLOSS tool that can do so in the selected language(s). [coding_standards_enforced]
    This MAY be implemented using static analysis tool(s) and/or by forcing the code through code reformatters. In many cases the tool configuration is included in the project's repository (since different projects may choose different configurations). Projects MAY allow style exceptions (and typically will); where exceptions occur, they MUST be rare and documented in the code at their locations, so that these exceptions can be reviewed and so that tools can automatically handle them in the future. Examples of such tools include ESLint (JavaScript), Rubocop (Ruby), and devtools check (R).

    Mechanically, in the gate and in the pre-commit hook: cargo fmt --check across
    every workspace including the detached ones, clippy with -D warnings on the
    embedded, host, TUI, emulator and fuzz targets, and rustdoc with
    RUSTDOCFLAGS=-D warnings. CI runs the same script, so a style violation cannot be
    merged.


  • Working build system


    Enough for a badge!

    Build systems for native binaries MUST honor the relevant compiler and linker (environment) variables passed in to them (e.g., CC, CFLAGS, CXX, CXXFLAGS, and LDFLAGS) and pass them to compiler and linker invocations. A build system MAY extend them with additional flags; it MUST NOT simply replace provided values with its own. If no native binaries are being generated, select "not applicable" (N/A). [build_standard_variables]
    It should be easy to enable special build features like Address Sanitizer (ASAN), or to comply with distribution hardening best practices (e.g., by easily turning on compiler flags to do so).

    The relevant conventions here are cargo's, and they are honored: RUSTFLAGS, the
    target triple, CARGO_TARGET_*_LINKER and the standard profile settings all work
    as expected for both the firmware and the native host tools. The one C/assembly
    unit is a bare-metal cross-compile for thumbv8m and deliberately pins
    arm-none-eabi-gcc, because the dev shell's host CC cannot produce a loadable
    object for a Cortex-M33 — honoring an injected CC there would yield a firmware
    image that does not boot.


    Enough for a badge!

    The build and installation system SHOULD preserve debugging information if they are requested in the relevant flags (e.g., "install -s" is not used). If there is no build or installation system (e.g., typical JavaScript libraries), select "not applicable" (N/A). [build_preserve_debug]
    E.G., setting CFLAGS (C) or CXXFLAGS (C++) should create the relevant debugging information if those languages are used, and they should not be stripped during installation. Debugging information is needed for support and analysis, and also useful for measuring the presence of hardening features in the compiled binaries.

    The release profile keeps full debug info (debug = 2) on purpose; the UF2 that
    gets flashed is unaffected because debug info is not part of the flashed image,
    and the gate itself reads symbol names out of the ELF. Nothing strips.


    Enough for a badge!

    The build system for the software produced by the project MUST NOT recursively build subdirectories if there are cross-dependencies in the subdirectories. If there is no build or installation system (e.g., typical JavaScript libraries), select "not applicable" (N/A). [build_non_recursive]
    The project build system's internal dependency information needs to be accurate, otherwise, changes to the project may not build correctly. Incorrect builds can lead to defects (including vulnerabilities). A common mistake in large build systems is to use a "recursive build" or "recursive make", that is, a hierarchy of subdirectories containing source files, where each subdirectory is independently built. Unless each subdirectory is fully independent, this is a mistake, because the dependency information is incorrect.

    Cargo workspaces, not recursive make. The dependency graph is explicit in the
    manifests, checked by scripts/crate_graph.py to be strictly tiered with no
    sideways edges, and enforced by cargo-deny. Nothing recurses into subdirectories
    to guess at ordering.


    Enough for a badge!

    The project MUST be able to repeat the process of generating information from source files and get exactly the same bit-for-bit result. If no building occurs (e.g., scripting languages where the source code is used directly instead of being compiled), select "not applicable" (N/A). [build_repeatable]
    GCC and clang users may find the -frandom-seed option useful; in some cases, this can be resolved by forcing some sort order. More suggestions can be found at the reproducible build site.

    nix build .#firmware is hermetic: the toolchain, the target and every tool are
    pinned by flake.lock, and dependencies by Cargo.lock. A scheduled repro job in
    the deep-checks workflow rebuilds and compares, so drift is caught rather than
    assumed absent.


  • Installation system


    Enough for a badge!

    The project MUST provide a way to easily install and uninstall the software produced by the project using a commonly-used convention. [installation_common]
    Examples include using a package manager (at the system or language level), "make install/uninstall" (supporting DESTDIR), a container in a standard format, or a virtual machine image in a standard format. The installation and uninstallation process (e.g., its packaging) MAY be implemented by a third party as long as it is FLOSS.

    The firmware installs the way every RP2350 board does: hold BOOTSEL, drag one
    .uf2 onto the drive that appears — or use the web flasher. Uninstall is flashing
    something else. The host CLI installs through the standard Python conventions
    (uv tool install ./tools, pipx install ./tools, or pip), all of which
    uninstall the same way.


    Enough for a badge!

    The installation system for end-users MUST honor standard conventions for selecting the location where built artifacts are written to at installation time. For example, if it installs files on a POSIX system it MUST honor the DESTDIR environment variable. If there is no installation system or no standard convention, select "not applicable" (N/A). [installation_standard_variables]

    The host tools honor the conventions of their ecosystems: uv/pipx/pip place the CLI in the standard user location and respect the active virtualenv or prefix, and cargo writes into the usual target directory. The firmware has no install prefix to honor — its destination is a fixed flash offset on the device.


    Enough for a badge!

    The project MUST provide a way for potential developers to quickly install all the project results and support environment necessary to make changes, including the tests and test environment. This MUST be performed with a commonly-used convention. [installation_development_quick]
    This MAY be implemented using a generated container and/or installation script(s). External dependencies would typically be installed by invoking system and/or language package manager(s), per external_dependencies.

    nix develop is the entire setup: Rust stable with the thumbv8m target,
    picotool, gitleaks, cargo-audit/deny and the Python stack, pinned by flake.lock.
    Entering the shell also installs the pre-commit hook. Without Nix,
    rust-toolchain.toml pins the toolchain and components for rustup.
    https://themaxmur.github.io/RS-Key/build.html


  • Externally-maintained components


    Enough for a badge!

    The project MUST list external dependencies in a computer-processable way. (URL required) [external_dependencies]
    Typically this is done using the conventions of package manager and/or build system. Note that this helps implement installation_development_quick.

    Machine-readable and pinned: Cargo.toml/Cargo.lock for the Rust side (plus
    separate lockfiles for the detached TUI, emulator and fuzz workspaces),
    flake.nix/flake.lock for the toolchain and tools, and pyproject for the host CLI.
    Git dependencies are restricted to the embassy organization.
    https://github.com/TheMaxMur/RS-Key/blob/main/Cargo.lock


    Enough for a badge!

    Projects MUST monitor or periodically check their external dependencies (including convenience copies) to detect known vulnerabilities, and fix exploitable vulnerabilities or verify them as unexploitable. [dependency_monitoring]
    This can be done using an origin analyzer / dependency checking tool / software composition analysis tool such as OWASP's Dependency-Check, Sonatype's Nexus Auditor, Synopsys' Black Duck Software Composition Analysis, and Bundler-audit (for Ruby). Some package managers include mechanisms to do this. It is acceptable if the components' vulnerability cannot be exploited, but this analysis is difficult and it is sometimes easier to simply update or fix the part.

    Three layers, all in the gate: cargo-audit against the RustSec advisory database, cargo-deny for advisories plus a license allow-list and a source policy, and cargo-vet for supply-chain review status. Dependabot opens update pull requests. No advisory is silently ignored — each entry in deny.toml carries its reason and its dependency chain.


    Enough for a badge!

    The project MUST either:
    1. make it easy to identify and update reused externally-maintained components; or
    2. use the standard components provided by the system or programming language.
    Then, if a vulnerability is found in a reused component, it will be easy to update that component. [updateable_reused_components]
    A typical way to meet this criterion is to use system and programming language package management systems. Many FLOSS programs are distributed with "convenience libraries" that are local copies of standard libraries (possibly forked). By itself, that's fine. However, if the program *must* use these local (forked) copies, then updating the "standard" libraries as a security update will leave these additional copies still vulnerable. This is especially an issue for cloud-based systems; if the cloud provider updates their "standard" libraries but the program won't use them, then the updates don't actually help. See, e.g., "Chromium: Why it isn't in Fedora yet as a proper package" by Tom Callaway.

    Every reused component is a versioned package in a lockfile, updated with
    cargo update or a flake input bump — there are no convenience copies of
    third-party source in the build. The vendored third-party test suites under
    third_party/ are test harnesses, not shipped code, and are identified as such.


    Enough for a badge!

    The project SHOULD avoid using deprecated or obsolete functions and APIs where FLOSS alternatives are available in the set of technology it uses (its "technology stack") and to a supermajority of the users the project supports (so that users have ready access to the alternative). [interfaces_current]

    Deprecations are compile errors here, not warnings: clippy runs with -D warnings and rustdoc with RUSTDOCFLAGS=-D warnings, so a deprecated API in the technology stack fails the gate the day the dependency marks it. Where the project stays on an older upstream it is a pinned, stated decision rather than drift.


  • Automated test suite


    Enough for a badge!

    An automated test suite MUST be applied on each check-in to a shared repository for at least one branch. This test suite MUST produce a report on test success or failure. [automated_integration_testing]
    This requirement can be viewed as a subset of test_continuous_integration, but focused on just testing, without requiring continuous integration.

    Every pull request and every push to main runs the same merge gate CI runs
    verbatim — nix develop -c ./scripts/check.sh, over a hundred rows — plus the
    emulator suites, which drive the real applet stack over a socket with no
    hardware. Results are reported per job on the pull request, and scheduled
    deep-check workflows run the slower tiers (fuzzing, Miri, Kani, coverage,
    reproducibility) daily and weekly.
    https://github.com/TheMaxMur/RS-Key/blob/main/.github/workflows/ci.yml


    Enough for a badge!

    The project MUST add regression tests to an automated test suite for at least 50% of the bugs fixed within the last six months. [regression_tests_added50]

    The written policy is that a bug fix starts by reproducing the bug — a failing
    host test where the logic is host-testable, a tests/*.py repro otherwise — and
    then fixes it. In practice the fixes of the last six months ship with their
    tests in the same commit, which is also what makes the gate able to tell a
    repaired defect from a rewritten one.


    Enough for a badge!

    The project MUST have FLOSS automated test suite(s) that provide at least 80% statement coverage if there is at least one FLOSS tool that can measure this criterion in the selected language. [test_statement_coverage80]
    Many FLOSS tools are available to measure test coverage, including gcov/lcov, Blanket.js, Istanbul, JCov, and covr (R). Note that meeting this criterion is not a guarantee that the test suite is thorough, instead, failing to meet this criterion is a strong indicator of a poor test suite.

    Measured and floored rather than estimated: the deep-checks workflow runs
    cargo llvm-cov --fail-under-lines 80 over the host crates, so coverage cannot
    silently fall below the bar. The most recent scheduled run reports 86.06% lines
    and 84.88% regions. (The floor excludes the firmware glue crate and the flash
    wiper, which are embedded-only and not host-executable by construction.)


  • New functionality testing


    Enough for a badge!

    The project MUST have a formal written policy that as major new functionality is added, tests for the new functionality MUST be added to an automated test suite. [test_policy_mandated]

    CONTRIBUTING.md states it as a requirement, not a preference: a protocol-visible
    change comes with a test at the level where it is visible — a host test if the
    logic is host-testable, a tests/*.py script if only the real USB stack exercises
    it — and a new parser comes with a new fuzz target. The pull request template
    asks how the change was tested.


    Enough for a badge!

    The project MUST include, in its documented instructions for change proposals, the policy that tests are to be added for major new functionality. [tests_documented_added]
    However, even an informal rule is acceptable as long as the tests are being added in practice.

    The policy is written in CONTRIBUTING.md ("Tests") and the pull request
    template asks how the change was tested.
    https://github.com/TheMaxMur/RS-Key/blob/main/CONTRIBUTING.md


  • Warning flags


    Enough for a badge!

    Projects MUST be maximally strict with warnings in the software produced by the project, where practical. [warnings_strict]
    Some warnings cannot be effectively enabled on some projects. What is needed is evidence that the project is striving to enable warning flags where it can, so that errors are detected early.

    -D warnings everywhere, no exceptions per crate; plus unsafe sites are
    enumerated and justified in docs/unsafe.md, and dependencies are gated by
    cargo-deny and cargo-vet. https://themaxmur.github.io/RS-Key/unsafe.html


 Security 13/13 ●

  • Secure development knowledge


    Enough for a badge!

    The project MUST implement secure design principles (from "know_secure_design"), where applicable. If the project is not producing software, select "not applicable" (N/A). [implement_secure_design]
    For example, the project results should have fail-safe defaults (access decisions should deny by default, and projects' installation should be secure by default). They should also have complete mediation (every access that might be limited must be checked for authority and be non-bypassable). Note that in some cases principles will conflict, in which case a choice must be made (e.g., many mechanisms can make things more complex, contravening "economy of mechanism" / keep it simple).

    The assurance case argues this explicitly rather than asserting it: each of
    Saltzer and Schroeder's principles against what the tree actually does —
    economy of mechanism (no_std, no allocator, no mutexes, ownership as
    synchronization), fail-safe defaults (alwaysUv on; a failed flash read is never
    laundered into an absence), complete mediation (authorization re-checked at use,
    a PIN retry spent before the comparison), open design, separation of privilege,
    least privilege (the partition table denies the bootloader the KV store; applets
    own disjoint file-id ranges; zero applet-to-applet edges, enforced by cargo-deny)
    and least common mechanism. https://themaxmur.github.io/RS-Key/assurance-case.html


  • Use basic good cryptographic practices

    Note that some software does not need to use cryptographic mechanisms. If your project produces software that (1) includes, activates, or enables encryption functionality, and (2) might be released from the United States (US) to outside the US or to a non-US-citizen, you may be legally required to take a few extra steps. Typically this just involves sending an email. For more information, see the encryption section of Understanding Open Source Technology & US Export Controls.

    Enough for a badge!

    The default security mechanisms within the software produced by the project MUST NOT depend on cryptographic algorithms or modes with known serious weaknesses (e.g., the SHA-1 cryptographic hash algorithm or the CBC mode in SSH). [crypto_weaknesses]
    Concerns about CBC mode in SSH are discussed in CERT: SSH CBC vulnerability.

    Same as crypto_working: SHA-1 is confined to HMAC constructions required by
    OATH/challenge-response interoperability, where no collision-resistance
    assumption is made; signatures use SHA-256 and above. AES-GCM is used with
    unique nonces per sealed record. The FIPS profile build drops every
    non-approved option, including secp256k1.
    https://themaxmur.github.io/RS-Key/guides/fips.html


    Enough for a badge!

    The project SHOULD support multiple cryptographic algorithms, so users can quickly switch if one is broken. Common symmetric key algorithms include AES, Twofish, and Serpent. Common cryptographic hash algorithm alternatives include SHA-2 (including SHA-224, SHA-256, SHA-384 AND SHA-512) and SHA-3. [crypto_algorithm_agility]

    Multiple algorithms in every slot that has one: ES256/ES384/ES512 and EdDSA for FIDO, with ML-DSA-44/-65/-87 alongside them; RSA-2048/3072/4096 and EC for OpenPGP and PIV; AES-128/192/256 for PIV management keys; SHA-1/SHA-256/SHA-512 HMAC for OATH as those specifications require. The FIPS-style profile build demonstrates the agility from the other side, dropping every non-approved option (including secp256k1) from both the advertised list and negotiation.


    Enough for a badge!

    The project MUST support storing authentication credentials (such as passwords and dynamic tokens) and private cryptographic keys in files that are separate from other information (such as configuration files, databases, and logs), and permit users to update and replace them without code recompilation. If the project never processes authentication credentials and private cryptographic keys, select "not applicable" (N/A). [crypto_credential_agility]

    No key or credential is compiled into the program. Private keys and secrets live
    in the device's flash KV store, sealed at rest and separate from the image; the
    secure-boot signing key is generated and held by the operator on their own host,
    never in this repository. The only keys that can be baked into a build are
    explicitly fake test keys behind FAKE_* build knobs, which exist so that a test
    image is distinguishable from a real one.


    Enough for a badge!

    The software produced by the project SHOULD support secure protocols for all of its network communications, such as SSHv2 or later, TLS1.2 or later (HTTPS), IPsec, SFTP, and SNMPv3. Insecure protocols such as FTP, HTTP, telnet, SSLv3 or earlier, and SSHv1 SHOULD be disabled by default, and only enabled if the user specifically configures it. If the software produced by the project does not support network communications, select "not applicable" (N/A). [crypto_used_network]

    The software has no network communications. It is USB firmware for a security key and a host CLI that talks to it over USB HID and CCID; there is no socket, no network stack and no remote endpoint.


    Enough for a badge!

    The software produced by the project SHOULD, if it supports or uses TLS, support at least TLS version 1.2. Note that the predecessor of TLS was called SSL. If the software does not use TLS, select "not applicable" (N/A). [crypto_tls12]

    The software neither supports nor uses TLS — there is no network interface.


    Enough for a badge!

    The software produced by the project MUST, if it supports TLS, perform TLS certificate verification by default when using TLS, including on subresources. If the software does not use TLS, select "not applicable" (N/A). [crypto_certificate_verification]
    Note that incorrect TLS certificate verification is a common mistake. For more information, see "The Most Dangerous Code in the World: Validating SSL Certificates in Non-Browser Software" by Martin Georgiev et al. and "Do you trust this application?" by Michael Catanzaro.

    The software does not support TLS; there is no network interface and no certificate chain to verify at runtime.


    Enough for a badge!

    The software produced by the project MUST, if it supports TLS, perform certificate verification before sending HTTP headers with private information (such as secure cookies). If the software does not use TLS, select "not applicable" (N/A). [crypto_verification_private]

    The software does not support TLS and sends no HTTP headers; it speaks USB protocols only.


  • Secure release


    Enough for a badge!

    The project MUST cryptographically sign releases of the project results intended for widespread use, and there MUST be a documented process explaining to users how they can obtain the public signing keys and verify the signature(s). The private key for these signature(s) MUST NOT be on site(s) used to directly distribute the software to the public. If releases are not intended for widespread use, select "not applicable" (N/A). [signed_releases]
    The project results include both source code and any generated deliverables where applicable (e.g., executables, packages, and containers). Generated deliverables MAY be signed separately from source code. These MAY be implemented as signed git tags (using cryptographic digital signatures). Projects MAY provide generated results separately from tools like git, but in those cases, the separate results MUST be separately signed.

    Each release publishes a SHA256SUMS file signed with keyless cosign, recorded in
    the Rekor transparency log, plus a GitHub build-provenance attestation (SLSA
    Build L3). Keyless signing means there is no public key for users to fetch and
    trust out of band — the identity is the release workflow in this repository,
    verifiable with cosign verify-blob against that identity. The commands are
    documented step by step.
    https://themaxmur.github.io/RS-Key/releases.html


    Enough for a badge!

    It is SUGGESTED that in the version control system, each important version tag (a tag that is part of a major release, minor release, or fixes publicly noted vulnerabilities) be cryptographically signed and verifiable as described in signed_releases. [version_tags_signed]

    Release tags are annotated and GPG-signed (git tag -s) as a step of the release
    pipeline; the most recent, v0.4.10, carries its signature in the tag object.


  • Other security issues


    Enough for a badge!

    The project results MUST check all inputs from potentially untrusted sources to ensure they are valid (an *allowlist*), and reject invalid inputs, if there are any restrictions on the data at all. [input_validation]
    Note that comparing input against a list of "bad formats" (aka a *denylist*) is normally not enough, because attackers can often work around a denylist. In particular, numbers are converted into internal formats and then checked if they are between their minimum and maximum (inclusive), and text strings are checked to ensure that they are valid text patterns (e.g., valid UTF-8, length, syntax, etc.). Some data may need to be "anything at all" (e.g., a file uploader), but these would typically be rare.

    Everything arriving over USB is untrusted and is parsed against what the specification allows, not against what is expected: CTAPHID framing, CBOR maps, ISO-7816 APDUs and the CCID bulk stream each reject structurally invalid input with the status the protocol defines rather than best-effort recovery. Lengths are checked against the buffers they index — there is no allocator to grow into — and every one of those parsers has a fuzz target, with a floor in the gate so the set cannot quietly empty.


    Enough for a badge!

    Hardening mechanisms SHOULD be used in the software produced by the project so that software defects are less likely to result in security vulnerabilities. [hardening]
    Hardening mechanisms may include HTTP headers like Content Security Policy (CSP), compiler flags to mitigate attacks (such as -fstack-protector), or compiler flags to eliminate undefined behavior. For our purposes least privilege is not considered a hardening mechanism (least privilege is important, but separate).

    Hardening is layered and most of it is on by default. The language: no_std Rust
    with no allocator, bounds-checked slices, and unsafe sites enumerated and
    justified. The image: optional secure boot with an anti-rollback epoch in OTP
    fuses, and a partition table carried in the shipped image that denies the USB
    bootloader read and write over the key store while secure code keeps it. The
    data: every secret AEAD-sealed before it reaches flash, through a single
    chokepoint. The process: retry counters with lockout, constant-time comparisons,
    and blinding on every private-key path.
    https://themaxmur.github.io/RS-Key/threat-model.html


    Enough for a badge!

    The project MUST provide an assurance case that justifies why its security requirements are met. The assurance case MUST include: a description of the threat model, clear identification of trust boundaries, an argument that secure design principles have been applied, and an argument that common implementation security weaknesses have been countered. (URL required) [assurance_case]
    An assurance case is "a documented body of evidence that provides a convincing and valid argument that a specified set of critical claims regarding a system’s properties are adequately justified for a given application in a given environment" ("Software Assurance Using Structured Assurance Case Models", Thomas Rhodes et al, NIST Interagency Report 7608). Trust boundaries are boundaries where data or execution changes its level of trust, e.g., a server's boundaries in a typical web application. It's common to list secure design principles (such as Saltzer and Schroeer) and common implementation security weaknesses (such as the OWASP top 10 or CWE/SANS top 25), and show how each are countered. The BadgeApp assurance case may be a useful example. This is related to documentation_security, documentation_architecture, and implement_secure_design.

    A dedicated assurance case page: what is claimed, the threat model it is claimed
    against, six explicitly identified trust boundaries (the USB cable, transport to
    worker, RAM to flash, the boot chain and partition table, the owner, and source
    to artifact), the secure-design-principles argument, and a table mapping common
    implementation weaknesses to what prevents each and where the evidence lives. It
    ends with the residuals it cannot justify.
    https://themaxmur.github.io/RS-Key/assurance-case.html


 Analysis 2/2 ●

  • Static code analysis


    Enough for a badge!

    The project MUST use at least one static analysis tool with rules or approaches to look for common vulnerabilities in the analyzed language or environment, if there is at least one FLOSS tool that can implement this criterion in the selected language. [static_analysis_common_vulnerabilities]
    Static analysis tools that are specifically designed to look for common vulnerabilities are more likely to find them. That said, using any static tools will typically help find some problems, so we are suggesting but not requiring this for the 'passing' level badge.

    CodeQL runs its security query suites for Rust and Python, and cargo-audit/cargo-deny match the dependency graph against the RustSec advisory database on every gate run.


  • Dynamic code analysis


    Enough for a badge!

    If the software produced by the project includes software written using a memory-unsafe language (e.g., C or C++), then at least one dynamic tool (e.g., a fuzzer or web application scanner) MUST be routinely used in combination with a mechanism to detect memory safety problems such as buffer overwrites. If the project does not produce software written in a memory-unsafe language, choose "not applicable" (N/A). [dynamic_analysis_unsafe]
    Examples of mechanisms to detect memory safety problems include Address Sanitizer (ASAN) (available in GCC and LLVM), Memory Sanitizer, and valgrind. Other potentially-used tools include thread sanitizer and undefined behavior sanitizer. Widespread assertions would also work.

    The firmware is Rust, memory-safe by default, and its few unsafe sites are
    enumerated and justified in docs/unsafe.md. Those paths are covered
    dynamically anyway: cargo-fuzz builds with AddressSanitizer, and
    scripts/miri-all.sh re-runs every fuzz target's logic under Miri's
    undefined-behaviour checker in CI.
    https://themaxmur.github.io/RS-Key/unsafe.html



You can use tools and AI systems to propose changes via a simple URL, such as https://www.bestpractices.dev/en/projects/14195/choose/edit?osps_ac_01_01_status=Met&osps_ac_01_01_justification=GitHub+enforced. See our automation proposals system for how to do that. This data is available under the Community Data License Agreement – Permissive, Version 2.0 (CDLA-Permissive-2.0). This means that a Data Recipient may share the Data, with or without modifications, so long as the Data Recipient makes available the text of this agreement with the shared Data. Please credit MaxMur and the OpenSSF Best Practices badge contributors.

Project badge entry owned by: MaxMur.
Entry created on 2026-08-21 16:19:55 UTC, last updated on 2026-09-21 09:10:45 UTC. Last achieved passing badge on 2026-08-28 13:59:33 UTC.