claustrum

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 Passing level criteria. You can also view the Silver or Gold level criteria.

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

        

 Basics 13/13

  • General

    Note that other projects may use the same name.

    A tiny, dependency-light Go daemon that hosts a remote Claude Code session over SSH: CLI-version manager + process supervisor + JSON-RPC multiplexer (with a replay buffer) over an AF_UNIX socket. Clean-room, cross-platform, no telemetry.

    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.
  • Basic project website content


    The project website MUST succinctly describe what the software does (what problem does it solve?). [description_good]
    This MUST be in language that potential users can understand (e.g., it uses minimal jargon).

    claustrum's purpose and capabilities are described in the README's first paragraph and in the GitHub repository description: a tiny, dependency-light Go daemon that hosts a remote Claude Code session over SSH (CLI-version manager + process supervisor + JSON-RPC multiplexer over an AF_UNIX socket). https://github.com/schubydoo/claustrum/blob/main/README.md



    The project website MUST provide information on how to: obtain, provide feedback (as bug reports or enhancements), and contribute to the software. [interact]

    CONTRIBUTING.md explains how to interact and contribute, and GitHub Issues is open to everyone. https://github.com/schubydoo/claustrum/blob/main/CONTRIBUTING.md



    The information on how to contribute MUST explain the contribution process (e.g., are pull requests used?) (URL required) [contribution]
    We presume that projects on GitHub use issues and pull requests unless otherwise noted. This information can be short, e.g., stating that the project uses pull requests, an issue tracker, or posts to a mailing list (which one?)

    Non-trivial contribution file in repository: https://github.com/schubydoo/claustrum/blob/main/CONTRIBUTING.md.



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

    CONTRIBUTING.md states the acceptable-contribution requirements: gofmt/go vet/golangci-lint clean, go test -race ./... green, make all cross-compiling for all six targets, tests for new or changed behavior with a 95% statement-coverage floor enforced in CI, Conventional Commit PR titles, and a .changeset fragment for user-facing changes. https://github.com/schubydoo/claustrum/blob/main/CONTRIBUTING.md


  • FLOSS license


    The software produced by the project MUST be released as FLOSS. [floss_license]
    FLOSS is software released in a way that meets the Open Source Definition or Free Software Definition. Examples of such licenses include the CC0, MIT, BSD 2-clause, BSD 3-clause revised, Apache 2.0, Lesser GNU General Public License (LGPL), and the GNU General Public License (GPL). For our purposes, this means that the license MUST be: The software MAY also be licensed other ways (e.g., "GPLv2 or proprietary" is acceptable).

    The Apache-2.0 license is approved by the Open Source Initiative (OSI).



    It is SUGGESTED that any required license(s) for the software produced by the project be approved by the Open Source Initiative (OSI). [floss_license_osi]
    The OSI uses a rigorous approval process to determine which licenses are OSS.

    The Apache-2.0 license is approved by the Open Source Initiative (OSI).



    The project MUST post the license(s) of its results in a standard location in their source repository. (URL required) [license_location]
    One convention is posting the license as a top-level file named LICENSE or COPYING, which MAY be followed by an extension such as ".txt" or ".md". An alternative convention is to have a directory named LICENSES containing license file(s); these files are typically named as their SPDX license identifier followed by an appropriate file extension, as described in the REUSE Specification. Note that this criterion is only a requirement on the source repository. You do NOT need to include the license file when generating something from the source code (such as an executable, package, or container). For example, when generating an R package for the Comprehensive R Archive Network (CRAN), follow standard CRAN practice: if the license is a standard license, use the standard short license specification (to avoid installing yet another copy of the text) and list the LICENSE file in an exclusion file such as .Rbuildignore. Similarly, when creating a Debian package, you may put a link in the copyright file to the license text in /usr/share/common-licenses, and exclude the license file from the created package (e.g., by deleting the file after calling dh_auto_install). We encourage including machine-readable license information in generated formats where practical.

    Non-trivial license location file in repository: https://github.com/schubydoo/claustrum/blob/main/LICENSE.


  • Documentation


    The project MUST provide basic documentation for the software produced by the project. [documentation_basics]
    This documentation must be in some media (such as text or video) that includes: how to install it, how to start it, how to use it (possibly with a tutorial using examples), and how to use it securely (e.g., what to do and what not to do) if that is an appropriate topic for the software. The security documentation need not be long. The project MAY use hypertext links to non-project material as documentation. If the project does not produce software, choose "not applicable" (N/A).

    Some documentation basics file contents found.



    The project MUST provide reference documentation that describes the external interface (both input and output) of the software produced by the project. [documentation_interface]
    The documentation of an external interface explains to an end-user or developer how to use it. This would include its application program interface (API) if the software has one. If it is a library, document the major classes/types and methods/functions that can be called. If it is a web application, define its URL interface (often its REST interface). If it is a command-line interface, document the parameters and options it supports. In many cases it's best if most of this documentation is automatically generated, so that this documentation stays synchronized with the software as it changes, but this isn't required. The project MAY use hypertext links to non-project material as documentation. Documentation MAY be automatically generated (where practical this is often the best way to do so). Documentation of a REST interface may be generated using Swagger/OpenAPI. Code interface documentation MAY be generated using tools such as JSDoc (JavaScript), ESDoc (JavaScript), pydoc (Python), devtools (R), pkgdown (R), and Doxygen (many). Merely having comments in implementation code is not sufficient to satisfy this criterion; there needs to be an easy way to see the information without reading through all the source code. If the project does not produce software, choose "not applicable" (N/A).

    The external interface is documented in full: docs/PROTOCOL.md specifies the JSON-RPC surface (all 19 server./files./git./process. methods, their parameters, result frames and error codes), the README and docs document the command-line flags for -serve/-bridge/-stop/-install, and docs/EXAMPLES.md gives worked client examples. https://github.com/schubydoo/claustrum/blob/main/docs/PROTOCOL.md


  • Other


    The project sites (website, repository, and download URLs) MUST support HTTPS using TLS. [sites_https]
    This requires that the project home page URL and the version control repository URL begin with "https:", not "http:". You can get free certificates from Let's Encrypt. Projects MAY implement this criterion using (for example) GitHub pages, GitLab pages, or SourceForge project pages. If you support HTTP, we urge you to redirect the HTTP traffic to HTTPS.

    Given only https: URLs.



    The project MUST have one or more mechanisms for discussion (including proposed changes and issues) that are searchable, allow messages and topics to be addressed by URL, enable new people to participate in some of the discussions, and do not require client-side installation of proprietary software. [discussion]
    Examples of acceptable mechanisms include archived mailing list(s), GitHub issue and pull request discussions, Bugzilla, Mantis, and Trac. Asynchronous discussion mechanisms (like IRC) are acceptable if they meet these criteria; make sure there is a URL-addressable archiving mechanism. Proprietary JavaScript, while discouraged, is permitted.

    GitHub supports discussions on issues and pull requests.



    The project SHOULD provide documentation in English and be able to accept bug reports and comments about code in English. [english]
    English is currently the lingua franca of computer technology; supporting English increases the number of different potential developers and reviewers worldwide. A project can meet this criterion even if its core developers' primary language is not English.

    All documentation, code comments, commit messages and issue/PR discussion are in English.



    The project MUST be maintained. [maintained]
    As a minimum, the project should attempt to respond to significant problem and vulnerability reports. A project that is actively pursuing a badge is probably maintained. All projects and people have limited resources, and typical projects must reject some proposed changes, so limited resources and proposal rejections do not by themselves indicate an unmaintained project.

    When a project knows that it will no longer be maintained, it should set this criterion to "Unmet" and use the appropriate mechanism(s) to indicate to others that it is not being maintained. For example, use “DEPRECATED” as the first heading of its README, add “DEPRECATED” near the beginning of its home page, add “DEPRECATED” to the beginning of its code repository project description, add a no-maintenance-intended badge in its README and/or home page, mark it as deprecated in any package repositories (e.g., npm deprecate), and/or use the code repository's marking system to archive it (e.g., GitHub's "archive" setting, GitLab’s "archived" marking, Gerrit's "readonly" status, or SourceForge’s "abandoned" project status). Additional discussion can be found here.

    The project is actively maintained: frequent commits, reviewed pull requests, and regular tagged releases (v1.9.0 on 2026-08-15). https://github.com/schubydoo/claustrum/commits/main


 Change Control 9/9

  • Public version-controlled source repository


    The project MUST have a version-controlled source repository that is publicly readable and has a URL. [repo_public]
    The URL MAY be the same as the project URL. The project MAY use private (non-public) branches in specific cases while the change is not publicly released (e.g., for fixing a vulnerability before it is revealed to the public).

    Repository on GitHub, which provides public git repositories with URLs.



    The project's source repository MUST track what changes were made, who made the changes, and when the changes were made. [repo_track]

    Repository on GitHub, which uses git. git can track the changes, who made them, and when they were made.



    To enable collaborative review, the project's source repository MUST include interim versions for review between releases; it MUST NOT include only final releases. [repo_interim]
    Projects MAY choose to omit specific interim versions from their public source repositories (e.g., ones that fix specific non-public security vulnerabilities, may never be publicly released, or include material that cannot be legally posted and are not in the final release).

    Interim changes between releases are public as commits, branches and pull requests in the same git repository.



    It is SUGGESTED that common distributed version control software be used (e.g., git) for the project's source repository. [repo_distributed]
    Git is not specifically required and projects can use centralized version control software (such as subversion) with justification.

    Repository on GitHub, which uses git. git is distributed.


  • Unique version numbering


    The project results MUST have a unique version identifier for each release intended to be used by users. [version_unique]
    This MAY be met in a variety of ways including a commit IDs (such as git commit id or mercurial changeset id) or a version number (including version numbers that use semantic versioning or date-based schemes like YYYYMMDD).

    Every release carries a unique Semantic Version: the version is held in the VERSION file, tagged as vX.Y.Z by the automated knope release workflow, and compiled into the binary by goreleaser (-X main.Version), so claustrum -version identifies the exact build. https://github.com/schubydoo/claustrum/releases



    It is SUGGESTED that the Semantic Versioning (SemVer) or Calendar Versioning (CalVer) version numbering format be used for releases. It is SUGGESTED that those who use CalVer include a micro level value. [version_semver]
    Projects should generally prefer whatever format is expected by their users, e.g., because it is the normal format used by their ecosystem. Many ecosystems prefer SemVer, and SemVer is generally preferred for application programmer interfaces (APIs) and software development kits (SDKs). CalVer tends to be used by projects that are large, have an unusually large number of independently-developed dependencies, have a constantly-changing scope, or are time-sensitive. It is SUGGESTED that those who use CalVer include a micro level value, because including a micro level supports simultaneously-maintained branches whenever that becomes necessary. Other version numbering formats may be used as version numbers, including git commit IDs or mercurial changeset IDs, as long as they uniquely identify versions. However, some alternatives (such as git commit IDs) can cause problems as release identifiers, because users may not be able to easily determine if they are up-to-date. The version ID format may be unimportant for identifying software releases if all recipients only run the latest version (e.g., it is the code for a single website or internet service that is constantly updated via continuous delivery).

    The project uses Semantic Versioning (MAJOR.MINOR.PATCH); the bump is derived from the .changeset fragments merged since the last release.



    It is SUGGESTED that projects identify each release within their version control system. For example, it is SUGGESTED that those using git identify each release using git tags. [version_tags]

    Each release is a semantic-version git tag (v1.0.0 through v1.9.0) created by the knope release workflow on the release commit on main, with a matching GitHub Release. https://github.com/schubydoo/claustrum/tags


  • Release notes


    The project MUST provide, in each release, release notes that are a human-readable summary of major changes in that release to help users determine if they should upgrade and what the upgrade impact will be. The release notes MUST NOT be the raw output of a version control log (e.g., the "git log" command results are not release notes). Projects whose results are not intended for reuse in multiple locations (such as the software for a single website or service) AND employ continuous delivery MAY select "N/A". (URL required) [release_notes]
    The release notes MAY be implemented in a variety of ways. Many projects provide them in a file named "NEWS", "CHANGELOG", or "ChangeLog", optionally with extensions such as ".txt", ".md", or ".html". Historically the term "change log" meant a log of every change, but to meet these criteria what is needed is a human-readable summary. The release notes MAY instead be provided by version control system mechanisms such as the GitHub Releases workflow.

    Non-trivial release notes file in repository: https://github.com/schubydoo/claustrum/blob/main/CHANGELOG.md.



    The release notes MUST identify every publicly known run-time vulnerability fixed in this release that already had a CVE assignment or similar when the release was created. This criterion may be marked as not applicable (N/A) if users typically cannot practically update the software themselves (e.g., as is often true for kernel updates). This criterion applies only to the project results, not to its dependencies. If there are no release notes or there have been no publicly known vulnerabilities, choose N/A. [release_notes_vulns]
    This criterion helps users determine if a given update will fix a vulnerability that is publicly known, to help users make an informed decision about updating. If users typically cannot practically update the software themselves on their computers, but must instead depend on one or more intermediaries to perform the update (as is often the case for a kernel and low-level software that is intertwined with a kernel), the project may choose "not applicable" (N/A) instead, since this additional information will not be helpful to those users. Similarly, a project may choose N/A if all recipients only run the latest version (e.g., it is the code for a single website or internet service that is constantly updated via continuous delivery). This criterion only applies to the project results, not its dependencies. Listing the vulnerabilities of all transitive dependencies of a project becomes unwieldy as dependencies increase and vary, and is unnecessary since tools that examine and track dependencies can do this in a more scalable way.

    No publicly known vulnerability has been fixed in any release to date: the project has published no security advisories and has received no vulnerability reports. https://github.com/schubydoo/claustrum/security/advisories


 Reporting 8/8

  • Bug-reporting process


    The project MUST provide a process for users to submit bug reports (e.g., using an issue tracker or a mailing list). (URL required) [report_process]

    Non-trivial SECURITY[.md] file found file in repository: https://github.com/schubydoo/claustrum/blob/main/SECURITY.md. [osps_do_02_01]



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

    GitHub Issues is the project's bug tracker. https://github.com/schubydoo/claustrum/issues



    The project MUST acknowledge a majority of bug reports submitted in the last 2-12 months (inclusive); the response need not include a fix. [report_responses]

    No external bug reports have been submitted yet — the issue tracker has received none to date. The maintainer monitors it and there is no backlog of unanswered reports. https://github.com/schubydoo/claustrum/issues



    The project SHOULD respond to a majority (>50%) of enhancement requests in the last 2-12 months (inclusive). [enhancement_responses]
    The response MAY be 'no' or a discussion about its merits. The goal is simply that there be some response to some requests, which indicates that the project is still alive. For purposes of this criterion, projects need not count fake requests (e.g., from spammers or automated systems). If a project is no longer making enhancements, please select "unmet" and include the URL that makes this situation clear to users. If a project tends to be overwhelmed by the number of enhancement requests, please select "unmet" and explain.

    No enhancement requests have been submitted yet. The maintainer monitors the issue tracker and will respond to requests as they arrive; the README and docs are explicit about the project's scope (behavioral compatibility with the protocol it implements), so the criteria for accepting an enhancement are public.



    The project MUST have a publicly available archive for reports and responses for later searching. (URL required) [report_archive]

    GitHub Issues provides a public, persistent, searchable archive of reports and their responses. https://github.com/schubydoo/claustrum/issues


  • Vulnerability report process


    The project MUST publish the process for reporting vulnerabilities on the project site. (URL required) [vulnerability_report_process]
    Projects hosted on GitHub SHOULD consider enabling privately reporting a security vulnerability. Projects on GitLab SHOULD consider using its ability for privately reporting a vulnerability. Projects MAY identify a mailing address on https://PROJECTSITE/security, often in the form security@example.org. This vulnerability reporting process MAY be the same as its bug reporting process. Vulnerability reports MAY always be public, but many projects have a private vulnerability reporting mechanism.

    SECURITY.md documents the vulnerability reporting process, the supported versions, and the project's threat model and scope. https://github.com/schubydoo/claustrum/blob/main/SECURITY.md



    If private vulnerability reports are supported, the project MUST include how to send the information in a way that is kept private. (URL required) [vulnerability_report_private]
    Examples include a private defect report submitted on the web using HTTPS (TLS) or an email encrypted using OpenPGP. If vulnerability reports are always public (so there are never private vulnerability reports), choose "not applicable" (N/A).

    Vulnerabilities are reported privately through GitHub private vulnerability reporting, which is enabled on the repository; SECURITY.md tells reporters not to open a public issue. https://github.com/schubydoo/claustrum/security/advisories/new



    The project's initial response time for any vulnerability report received in the last 6 months MUST be less than or equal to 14 days. [vulnerability_report_response]
    If there have been no vulnerabilities reported in the last 6 months, choose "not applicable" (N/A).

    SECURITY.md commits to an initial response within a few days, followed by coordinated disclosure and credit. https://github.com/schubydoo/claustrum/blob/main/SECURITY.md


 Quality 13/13

  • Working build system


    If the software produced by the project requires building for use, the project MUST provide a working build system that can automatically rebuild the software from source code. [build]
    A build system determines what actions need to occur to rebuild the software (and in what order), and then performs those steps. For example, it can invoke a compiler to compile the source code. If an executable is created from source code, it must be possible to modify the project's source code and then generate an updated executable with those modifications. If the software produced by the project depends on external libraries, the build system does not need to build those external libraries. If there is no need to build anything to use the software after its source code is modified, select "not applicable" (N/A).

    Non-trivial build file in repository: https://github.com/schubydoo/claustrum/blob/main/Makefile.



    It is SUGGESTED that common tools be used for building the software. [build_common_tools]
    For example, Maven, Ant, cmake, the autotools, make, rake (Ruby), or devtools (R).

    Non-trivial build file in repository: https://github.com/schubydoo/claustrum/blob/main/Makefile.



    The project SHOULD be buildable using only FLOSS tools. [build_floss_tools]

    All build tooling is FLOSS: the Go toolchain (BSD-3), make (GPL), goreleaser (MIT), syft and cosign (Apache-2.0). The dependency set is stdlib plus klauspost/compress, and golang.org/x/sys and Microsoft/go-winio on Windows only — all FLOSS.


  • Automated test suite


    The project MUST use at least one automated test suite that is publicly released as FLOSS (this test suite may be maintained as a separate FLOSS project). The project MUST clearly show or document how to run the test suite(s) (e.g., via a continuous integration (CI) script or via documentation in files such as BUILD.md, README.md, or CONTRIBUTING.md). [test]
    The project MAY use multiple automated test suites (e.g., one that runs quickly, vs. another that is more thorough but requires special equipment). There are many test frameworks and test support systems available, including Selenium (web browser automation), Junit (JVM, Java), RUnit (R), testthat (R).

    The repository has an automated test suite of 438 test and fuzz functions covering the whole daemon two ways: fast unit tests, and a socket-integration suite that boots the daemon on a temporary AF_UNIX socket and asserts every method's JSON-RPC frames against golden fixtures in testdata/.



    A test suite SHOULD be invocable in a standard way for that language. [test_invocation]
    For example, "make check", "mvn test", or "rake test" (Ruby).

    The standard invocation is a single documented command, go test -race ./..., given in both CONTRIBUTING.md and CLAUDE.md. https://github.com/schubydoo/claustrum/blob/main/CONTRIBUTING.md



    It is SUGGESTED that the test suite cover most (or ideally all) the code branches, input fields, and functionality. [test_most]

    Statement coverage is approximately 98%, measured with -coverpkg=./... and enforced by a merge-blocking CI floor of 95%; coverage is also reported to Codecov on every pull request.



    It is SUGGESTED that the project implement continuous integration (where new or changed code is frequently integrated into a central code repository and automated tests are run on the result). [test_continuous_integration]

    GitHub Actions runs the full suite with the race detector on every push and pull request across a Linux, macOS and Windows matrix, alongside lint, six-target cross-build and coverage jobs. https://github.com/schubydoo/claustrum/actions/workflows/ci.yml


  • New functionality testing


    The project MUST have a general policy (formal or not) that as major new functionality is added to the software produced by the project, tests of that functionality should be added to an automated test suite. [test_policy]
    As long as a policy is in place, even by word of mouth, that says developers should add tests to the automated test suite for major new functionality, select "Met."

    CONTRIBUTING.md requires tests for new or changed behavior, and the policy is enforced mechanically: a merge-blocking 95% statement-coverage floor in CI, plus golden-fixture tests that any wire-surface change must update deliberately.



    The project MUST have evidence that the test_policy for adding tests has been adhered to in the most recent major changes to the software produced by the project. [tests_are_added]
    Major functionality would typically be mentioned in the release notes. Perfection is not required, merely evidence that tests are typically being added in practice to the automated test suite when new major functionality is added to the software produced by the project.

    New functionality lands with tests in the same pull request; the coverage floor and the golden-fixture assertions block merges that would leave a change unexercised. Periodic mutation testing (gremlins) audits whether the added tests actually assert on behavior.



    It is SUGGESTED that this policy on adding tests (see test_policy) be documented in the instructions for change proposals. [tests_documented_added]
    However, even an informal rule is acceptable as long as the tests are being added in practice.

    The test-and-coverage policy is written down in CONTRIBUTING.md's "Before opening a PR" section and enforced by the coverage job in .github/workflows/ci.yml. https://github.com/schubydoo/claustrum/blob/main/CONTRIBUTING.md


  • Warning flags


    The project MUST enable one or more compiler warning flags, a "safe" language mode, or use a separate "linter" tool to look for code quality errors or common simple mistakes, if there is at least one FLOSS tool that can implement this criterion in the selected language. [warnings]
    Examples of compiler warning flags include gcc/clang "-Wall". Examples of a "safe" language mode include JavaScript "use strict" and perl5's "use warnings". A separate "linter" tool is simply a tool that examines the source code to look for code quality errors or common simple mistakes. These are typically enabled within the source code or build instructions.

    Compiler and analyzer warnings are enabled project-wide: gofmt -l, go vet ./..., and golangci-lint (the standard set — errcheck, govet, ineffassign, staticcheck, unused — plus misspell and unconvert; config in .golangci.yml) all run in CI, alongside CodeQL for Go.



    The project MUST address warnings. [warnings_fixed]
    These are the warnings identified by the implementation of the warnings criterion. The project should fix warnings or mark them in the source code as false positives. Ideally there would be no warnings, but a project MAY accept some warnings (typically less than 1 warning per 100 lines or less than 10 warnings).

    CI fails on any gofmt, go vet or golangci-lint finding, so warnings are fixed before merge and none is tolerated on main. CodeQL alerts are raised in the Security tab and triaged there.



    It is SUGGESTED that projects 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.

    Warnings are treated as errors: the lint job is a required check, so a single finding blocks the merge.


 Security 16/16

  • Secure development knowledge


    The project MUST have at least one primary developer who knows how to design secure software. (See ‘details’ for the exact requirements.) [know_secure_design]
    This requires understanding the following design principles, including the 8 principles from Saltzer and Schroeder:
    • economy of mechanism (keep the design as simple and small as practical, e.g., by adopting sweeping simplifications)
    • fail-safe defaults (access decisions should deny by default, and projects' installation should be secure by default)
    • complete mediation (every access that might be limited must be checked for authority and be non-bypassable)
    • open design (security mechanisms should not depend on attacker ignorance of its design, but instead on more easily protected and changed information like keys and passwords)
    • separation of privilege (ideally, access to important objects should depend on more than one condition, so that defeating one protection system won't enable complete access. E.G., multi-factor authentication, such as requiring both a password and a hardware token, is stronger than single-factor authentication)
    • least privilege (processes should operate with the least privilege necessary)
    • least common mechanism (the design should minimize the mechanisms common to more than one user and depended on by all users, e.g., directories for temporary files)
    • psychological acceptability (the human interface must be designed for ease of use - designing for "least astonishment" can help)
    • limited attack surface (the attack surface - the set of the different points where an attacker can try to enter or extract data - should be limited)
    • input validation with allowlists (inputs should typically be checked to determine if they are valid before they are accepted; this validation should use allowlists (which only accept known-good values), not denylists (which attempt to list known-bad values)).
    A "primary developer" in a project is anyone who is familiar with the project's code base, is comfortable making changes to it, and is acknowledged as such by most other participants in the project. A primary developer would typically make a number of contributions over the past year (via code, documentation, or answering questions). Developers would typically be considered primary developers if they initiated the project (and have not left the project more than three years ago), have the option of receiving information on a private vulnerability reporting channel (if there is one), can accept commits on behalf of the project, or perform final releases of the project software. If there is only one developer, that individual is the primary developer. Many books and courses are available to help you understand how to develop more secure software and discuss design. For example, the Secure Software Development Fundamentals course is a free set of three courses that explain how to develop more secure software (it's free if you audit it; for an extra fee you can earn a certificate to prove you learned the material).

    The design applies least privilege and a documented trust boundary (SECURITY.md): the daemon listens only on an owner-only (0600) AF_UNIX socket, makes no outbound connections in -serve mode, authenticates every method except the deliberate shutdown parity case with a constant-time (crypto/subtle) token comparison, keeps the token out of argv and the environment (-token-file is unlinked after reading, -token-fd is handed over a pipe, and the daemon's own daemon.token reconnect file is mode 0600 beside the socket), verifies a -cli-url download against SHA-256 before extracting, and guards both caller-supplied recursive-delete paths with an always-on home-directory guard. Optional surfaces (metrics, wire log, Windows named pipe, keep-children) all default off and each is documented with its security consequence. https://github.com/schubydoo/claustrum/blob/main/SECURITY.md



    At least one of the project's primary developers MUST know of common kinds of errors that lead to vulnerabilities in this kind of software, as well as at least one method to counter or mitigate each of them. [know_common_errors]
    Examples (depending on the type of software) include SQL injection, OS injection, classic buffer overflow, cross-site scripting, missing authentication, and missing authorization. See the CWE/SANS top 25 or OWASP Top 10 for commonly used lists. Many books and courses are available to help you understand how to develop more secure software and discuss common implementation errors that lead to vulnerabilities. For example, the Secure Software Development Fundamentals course is a free set of three courses that explain how to develop more secure software (it's free if you audit it; for an extra fee you can earn a certificate to prove you learned the material).

    The code is written against the common error classes for a local daemon: every caller-supplied path is normalized and both caller-supplied recursive-delete paths are refused by an always-on home-directory guard (homeguard.go); process.spawn builds argv slices and invokes no shell, runs children in their own process group, and strips the auth token from their environment; the per-connection frame reader is capped at 1 MiB and the async stdin queue at 8 MiB with backpressure; the token comparison is constant-time; and the socket is created mode 0600. CodeQL runs over this class of check in CI, and the threat model — including the resource limits deliberately left off for behavioral parity — is written down in SECURITY.md and docs/DIVERGENCES.md. https://github.com/schubydoo/claustrum/blob/main/SECURITY.md


  • 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.

    The software produced by the project MUST use, by default, only cryptographic protocols and algorithms that are publicly published and reviewed by experts (if cryptographic protocols and algorithms are used). [crypto_published]
    These cryptographic criteria do not always apply because some software has no need to directly use cryptographic capabilities.

    The only cryptography used is publicly published and expert-reviewed: SHA-256 (FIPS 180-4) for download verification and the operating system CSPRNG via crypto/rand. There are no home-grown algorithms or protocols.



    If the software produced by the project is an application or library, and its primary purpose is not to implement cryptography, then it SHOULD only call on software specifically designed to implement cryptographic functions; it SHOULD NOT re-implement its own. [crypto_call]

    All cryptographic mechanisms are called from the Go standard library (crypto/sha256, crypto/subtle, crypto/rand, crypto/tls via net/http); the project implements no cryptography of its own.



    All functionality in the software produced by the project that depends on cryptography MUST be implementable using FLOSS. [crypto_floss]

    The Go standard library, which supplies every cryptographic mechanism used, is FLOSS (BSD-3-Clause).



    The security mechanisms within the software produced by the project MUST use default keylengths that at least meet the NIST minimum requirements through the year 2030 (as stated in 2012). It MUST be possible to configure the software so that smaller keylengths are completely disabled. [crypto_keylength]
    These minimum bitlengths are: symmetric key 112, factoring modulus 2048, discrete logarithm key 224, discrete logarithmic group 2048, elliptic curve 224, and hash 224 (password hashing is not covered by this bitlength, more information on password hashing can be found in the crypto_password_storage criterion). See https://www.keylength.com for a comparison of keylength recommendations from various organizations. The software MAY allow smaller keylengths in some configurations (ideally it would not, since this allows downgrade attacks, but shorter keylengths are sometimes necessary for interoperability).

    claustrum generates and negotiates no long-term cryptographic keys. Its integrity check is SHA-256 (256-bit digest), and the HTTPS client used by -install relies on Go's crypto/tls defaults (TLS 1.3 / ECDHE with modern key sizes). The 64-bit crypto/rand value in the optional Windows pipe name is a uniqueness token, not a secret — access control there is the pipe's owner-only DACL, and the name is published in rpc.pipe by design.



    The default security mechanisms within the software produced by the project MUST NOT depend on broken cryptographic algorithms (e.g., MD4, MD5, single DES, RC4, Dual_EC_DRBG), or use cipher modes that are inappropriate to the context, unless they are necessary to implement an interoperable protocol (where the protocol implemented is the most recent version of that standard broadly supported by the network ecosystem, that ecosystem requires the use of such an algorithm or mode, and that ecosystem does not offer any more secure alternative). The documentation MUST describe any relevant security risks and any known mitigations if these broken algorithms or modes are necessary for an interoperable protocol. [crypto_working]
    ECB mode is almost never appropriate because it reveals identical blocks within the ciphertext as demonstrated by the ECB penguin, and CTR mode is often inappropriate because it does not perform authentication and causes duplicates if the input state is repeated. In many cases it's best to choose a block cipher algorithm mode designed to combine secrecy and authentication, e.g., Galois/Counter Mode (GCM) and EAX. Projects MAY allow users to enable broken mechanisms (e.g., during configuration) where necessary for compatibility, but then users know they're doing it.

    No broken or known-risky algorithm is used for a security purpose: SHA-256 for integrity, crypto/subtle for constant-time comparison, crypto/rand for randomness. MD5 and SHA-1 appear nowhere.



    The default security mechanisms within the software produced by the project SHOULD 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.

    No default configuration uses a cryptographic algorithm with known serious weaknesses; SHA-256 is the only hash function in the codebase and TLS is left at Go's secure stdlib defaults.



    The security mechanisms within the software produced by the project SHOULD implement perfect forward secrecy for key agreement protocols so a session key derived from a set of long-term keys cannot be compromised if one of the long-term keys is compromised in the future. [crypto_pfs]

    The only key agreement claustrum performs is as an HTTPS client, when -install fetches a CLI archive from a -cli-url; that uses Go's crypto/tls defaults, which are forward-secret (TLS 1.3, or ECDHE cipher suites on TLS 1.2). The daemon itself serves a local AF_UNIX socket (or a local Windows named pipe) and negotiates no keys.



    If the software produced by the project causes the storing of 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). See also OWASP Password Storage Cheat Sheet. [crypto_password_storage]
    This criterion applies only when the software is enforcing authentication of users using passwords for external users (aka inbound authentication), such as server-side web applications. It does not apply in cases where the software stores passwords for authenticating into other systems (aka outbound authentication, e.g., the software implements a client for some other system), since at least parts of that software must have often access to the unhashed password.

    claustrum stores no user passwords and has no user accounts. Authentication is a bearer token supplied by the launching client, compared in constant time; the daemon persists it beside the socket as a mode-0600 file for reconnect (a documented behavior of the protocol it implements) and unlinks it on graceful shutdown. No password is ever stored, hashed or otherwise. https://github.com/schubydoo/claustrum/blob/main/SECURITY.md



    The security mechanisms within the software produced by the project MUST generate all cryptographic keys and nonces using a cryptographically secure random number generator, and MUST NOT do so using generators that are cryptographically insecure. [crypto_random]
    A cryptographically secure random number generator may be a hardware random number generator, or it may be a cryptographically secure pseudo-random number generator (CSPRNG) using an algorithm such as Hash_DRBG, HMAC_DRBG, CTR_DRBG, Yarrow, or Fortuna. Examples of calls to secure random number generators include Java's java.security.SecureRandom and JavaScript's window.crypto.getRandomValues. Examples of calls to insecure random number generators include Java's java.util.Random and JavaScript's Math.random.

    Security-relevant randomness comes from crypto/rand (the OS CSPRNG). math/rand is not used anywhere in the codebase.


  • Secured delivery against man-in-the-middle (MITM) attacks


    The project MUST use a delivery mechanism that counters MITM attacks. Using https or ssh+scp is acceptable. [delivery_mitm]
    An even stronger mechanism is releasing the software with digitally signed packages, since that mitigates attacks on the distribution system, but this only works if the users can be confident that the public keys for signatures are correct and if the users will actually check the signature.

    Distribution channels use HTTPS exclusively. [osps_br_03_02]



    A cryptographic hash (e.g., a sha1sum) MUST NOT be retrieved over http and used without checking for a cryptographic signature. [delivery_unsigned]
    These hashes can be modified in transit.

    The documented installation paths are all authenticated HTTPS: a signed release archive from GitHub Releases (checksums.txt, cosign .sigstore.json signatures and SLSA provenance published alongside), go install github.com/schubydoo/claustrum@latest through the Go module proxy and checksum database, or a build from source. Users are never directed to fetch code over an unencrypted or unauthenticated channel.


  • Publicly known vulnerabilities fixed


    There MUST be no unpatched vulnerabilities of medium or higher severity that have been publicly known for more than 60 days. [vulnerabilities_fixed_60_days]
    The vulnerability must be patched and released by the project itself (patches may be developed elsewhere). A vulnerability becomes publicly known (for this purpose) once it has a CVE with publicly released non-paywalled information (reported, for example, in the National Vulnerability Database) or when the project has been informed and the information has been released to the public (possibly by the project). A vulnerability is considered medium or higher severity if its Common Vulnerability Scoring System (CVSS) base qualitative score is medium or higher. In CVSS versions 2.0 through 3.1, this is equivalent to a CVSS score of 4.0 or higher. Projects may use the CVSS score as published in a widely-used vulnerability database (such as the National Vulnerability Database) using the most-recent version of CVSS reported in that database. Projects may instead calculate the severity themselves using the latest version of CVSS at the time of the vulnerability disclosure, if the calculation inputs are publicly revealed once the vulnerability is publicly known. Note: this means that users might be left vulnerable to all attackers worldwide for up to 60 days. This criterion is often much easier to meet than what Google recommends in Rebooting responsible disclosure, because Google recommends that the 60-day period start when the project is notified even if the report is not public. Also note that this badge criterion, like other criteria, applies to the individual project. Some projects are part of larger umbrella organizations or larger projects, possibly in multiple layers, and many projects feed their results to other organizations and projects as part of a potentially-complex supply chain. An individual project often cannot control the rest, but an individual project can work to release a vulnerability patch in a timely way. Therefore, we focus solely on the individual project's response time. Once a patch is available from the individual project, others can determine how to deal with the patch (e.g., they can update to the newer version or they can apply just the patch as a cherry-picked solution).

    No vulnerability has been reported in claustrum itself. Dependency vulnerabilities are surfaced by Renovate, GitHub dependency alerts, the dependency-review check on pull requests and a Trivy filesystem scan of go.sum, and are patched promptly — well inside 60 days. The dependency set is deliberately tiny (stdlib plus one cross-platform module and two Windows-only ones).



    Projects SHOULD fix all critical vulnerabilities rapidly after they are reported. [vulnerabilities_critical_fixed]

    There are no known unpatched vulnerabilities of any severity. CodeQL and Trivy run on pull requests, on pushes to main and on a weekly schedule; dependency review runs on pull requests; OpenSSF Scorecard runs on pushes to main and weekly. Renovate and GitHub dependency alerts surface new findings between runs.


  • Other security issues


    The public repositories MUST NOT leak a valid private credential (e.g., a working password or private key) that is intended to limit public access. [no_leaked_credentials]
    A project MAY leak "sample" credentials for testing and unimportant databases, as long as they are not intended to limit public access.

    The repository contains no credentials. Gitleaks runs over full history in CI and GitHub secret scanning is enabled; host-specific and diagnostic material is gitignored; the daemon reads its token from a file it immediately unlinks or from a file descriptor, never from a committed file, and the optional wire log redacts credential-bearing keys and is created mode 0600.


 Analysis 8/8

  • Static code analysis


    At least one static code analysis tool (beyond compiler warnings and "safe" language modes) MUST be applied to any proposed major production release of the software before its release, if there is at least one FLOSS tool that implements this criterion in the selected language. [static_analysis]
    A static code analysis tool examines the software code (as source code, intermediate code, or executable) without executing it with specific inputs. For purposes of this criterion, compiler warnings and "safe" language modes do not count as static code analysis tools (these typically avoid deep analysis because speed is vital). Some static analysis tools focus on detecting generic defects, others focus on finding specific kinds of defects (such as vulnerabilities), and some do a combination. Examples of such static code analysis tools include cppcheck (C, C++), clang static analyzer (C, C++), SpotBugs (Java), FindBugs (Java) (including FindSecurityBugs), PMD (Java), Brakeman (Ruby on Rails), lintr (R), goodpractice (R), Coverity Quality Analyzer, SonarQube, Codacy, and HP Enterprise Fortify Static Code Analyzer. Larger lists of tools can be found in places such as the Wikipedia list of tools for static code analysis, OWASP information on static code analysis, NIST list of source code security analyzers, and Wheeler's list of static analysis tools. If there are no FLOSS static analysis tools available for the implementation language(s) used, you may select 'N/A'.

    Static analysis runs in CI on every pull request and push: go vet, golangci-lint (errcheck, govet, ineffassign, staticcheck, unused, misspell, unconvert; config in .golangci.yml), gitleaks over full history, and CodeQL for Go. Trivy (go.sum) and zizmor (GitHub Actions workflow security) run when those files change on a pull request, and unconditionally on pushes to main and on the weekly schedule, alongside OpenSSF Scorecard. https://github.com/schubydoo/claustrum/blob/main/.github/workflows/security.yml



    It is SUGGESTED that at least one of the static analysis tools used for the static_analysis criterion include rules or approaches to look for common vulnerabilities in the analyzed language or environment. [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's Go security query suite specifically targets common vulnerability patterns (injection, path traversal, unsafe process execution); Trivy targets known-vulnerable dependencies and zizmor targets the CI supply-chain class (script injection, over-broad token permissions, unpinned actions).



    All medium and higher severity exploitable vulnerabilities discovered with static code analysis MUST be fixed in a timely way after they are confirmed. [static_analysis_fixed]
    A vulnerability is considered medium or higher severity if its Common Vulnerability Scoring System (CVSS) base qualitative score is medium or higher. In CVSS versions 2.0 through 3.1, this is equivalent to a CVSS score of 4.0 or higher. Projects may use the CVSS score as published in a widely-used vulnerability database (such as the National Vulnerability Database) using the most-recent version of CVSS reported in that database. Projects may instead calculate the severity themselves using the latest version of CVSS at the time of the vulnerability disclosure, if the calculation inputs are publicly revealed once the vulnerability is publicly known. Note that criterion vulnerabilities_fixed_60_days requires that all such vulnerabilities be fixed within 60 days of being made public.

    Static-analysis findings are merge-blocking — the CI and security aggregator checks are required by the branch ruleset, and every scanner job fails on a finding — so they are fixed before a change reaches main. CodeQL alerts land in the Security tab and are triaged there.



    It is SUGGESTED that static source code analysis occur on every commit or at least daily. [static_analysis_often]

    Static analysis runs on every pull request and every push to main, and again on a weekly schedule (CodeQL, Trivy, Scorecard) so newly published rules and advisories are applied to unchanged code too.


  • Dynamic code analysis


    It is SUGGESTED that at least one dynamic analysis tool be applied to any proposed major production release of the software before its release. [dynamic_analysis]
    A dynamic analysis tool examines the software by executing it with specific inputs. For example, the project MAY use a fuzzing tool (e.g., American Fuzzy Lop) or a web application scanner (e.g., OWASP ZAP or w3af). In some cases the OSS-Fuzz project may be willing to apply fuzz testing to your project. For purposes of this criterion the dynamic analysis tool needs to vary the inputs in some way to look for various kinds of problems or be an automated test suite with at least 80% branch coverage. The Wikipedia page on dynamic analysis and the OWASP page on fuzzing identify some dynamic analysis tools. The analysis tool(s) MAY be focused on looking for security vulnerabilities, but this is not required.

    The Go race detector (a dynamic instrumentation tool) runs over the entire suite — including the socket-integration tests that drive a live daemon with concurrent dispatch — on every pull request across Linux, macOS and Windows. The repository also ships two native Go fuzz targets over the untrusted-input paths, FuzzDispatch (raw JSON-RPC frames) and FuzzBindParams (parameter binding); their seed corpora run in CI on every push, and extended fuzzing runs are performed out of band rather than on a CI schedule. A weekly mutation-testing run (gremlins) audits the strength of the suite's assertions.



    It is SUGGESTED that 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) 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.

    claustrum is written in Go and built with CGO_ENABLED=0, so no C or C++ is compiled or linked into the binary and memory-safety sanitizers do not apply. Concurrency errors, the relevant residual class, are covered by the race detector on every CI run across Linux, macOS and Windows.



    It is SUGGESTED that the project use a configuration for at least some dynamic analysis (such as testing or fuzzing) which enables many assertions. In many cases these assertions should not be enabled in production builds. [dynamic_analysis_enable_assertions]
    This criterion does not suggest enabling assertions during production; that is entirely up to the project and its users to decide. This criterion's focus is instead to improve fault detection during dynamic analysis before deployment. Enabling assertions in production use is completely different from enabling assertions during dynamic analysis (such as testing). In some cases enabling assertions in production use is extremely unwise (especially in high-integrity components). There are many arguments against enabling assertions in production, e.g., libraries should not crash callers, their presence may cause rejection by app stores, and/or activating an assertion in production may expose private data such as private keys. Beware that in many Linux distributions NDEBUG is not defined, so C/C++ assert() will by default be enabled for production in those environments. It may be important to use a different assertion mechanism or defining NDEBUG for production in those environments.

    The test suite runs with all assertions active — the integration suite asserts every method's JSON-RPC frames byte for byte against golden fixtures — and the race detector is enabled throughout.



    All medium and higher severity exploitable vulnerabilities discovered with dynamic code analysis MUST be fixed in a timely way after they are confirmed. [dynamic_analysis_fixed]
    If you are not running dynamic code analysis and thus have not found any vulnerabilities in this way, choose "not applicable" (N/A). A vulnerability is considered medium or higher severity if its Common Vulnerability Scoring System (CVSS) base qualitative score is medium or higher. In CVSS versions 2.0 through 3.1, this is equivalent to a CVSS score of 4.0 or higher. Projects may use the CVSS score as published in a widely-used vulnerability database (such as the National Vulnerability Database) using the most-recent version of CVSS reported in that database. Projects may instead calculate the severity themselves using the latest version of CVSS at the time of the vulnerability disclosure, if the calculation inputs are publicly revealed once the vulnerability is publicly known.

    No medium or higher severity exploitable vulnerability has been found by dynamic analysis to date; the race-detector and fuzz runs have produced no such finding to fix.



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 Schuby and the OpenSSF Best Practices badge contributors.

Project badge entry owned by: Schuby.
Entry created on 2026-08-18 15:39:02 UTC, last updated on 2026-08-18 16:09:32 UTC. Last achieved passing badge on 2026-08-18 16:09:32 UTC.