presidio-hardened-x402

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.

    Security middleware for x402 agentic payments — PII redaction, spending policy, and replay detection before blockchain commit

    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/presidio-v/presidio-hardened-x402/blob/main/CONTRIBUTING.md
    "How changes are made" documents the fork → branch → PR flow against main.


  • 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.

    Every commit must carry a DCO Signed-off-by line (git commit -s); enforced in review. Documented at https://github.com/presidio-v/presidio-hardened-x402/blob/main/CONTRIBUTING.md#licensing-and-developer-certificate-of-origin-dco. Inbound = outbound MIT.


    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.

    Maintainer-led single-steward model documented at https://github.com/presidio-v/presidio-hardened-x402/blob/main/GOVERNANCE.md — decision-making, escalation to PRESIDIO, and security/API change rules.


    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 at https://github.com/presidio-v/presidio-hardened-x402/blob/main/CODE_OF_CONDUCT.md (standard location).


    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.

    Key roles (steward org, maintainer, security contact, release manager, contributor) documented at https://github.com/presidio-v/presidio-hardened-x402/blob/main/GOVERNANCE.md#roles-and-responsibilities.


    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]

    See https://github.com/presidio-v/presidio-hardened-x402/blob/main/GOVERNANCE.md#project-continuity. Continuity is a property of the steward organisation, not one person: the repo is owned by the presidio-v GitHub org (not a personal account); PyPI publishing uses GitHub Trusted Publishing (OIDC) bound to the org repo + a gated release environment, so there is no personal token that dies with an individual; the release signing key is held in the organisation password manager (custody with PRESIDIO leadership) and is recoverable; the release process is fully documented; and PRESIDIO is a staffed organisation with more than one person able to assume each role. Issue triage, change acceptance, and releases can therefore continue within one week if any single individual becomes unavailable.


    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.

    Bus factor is backed by the PRESIDIO organisation rather than a lone maintainer: more than one person can assume the maintainer, security-contact, and release-manager roles, and all release credentials are org-held and recoverable (not tied to one machine). See https://github.com/presidio-v/presidio-hardened-x402/blob/main/GOVERNANCE.md#project-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.

    https://github.com/presidio-v/presidio-hardened-x402#roadmap includes a "Planned direction (next 12 months)" section covering intended work: toward v1.0 / mainnet gate, prompt-injection scanning (#23), broader rail coverage, and evidence/conformance growth.


    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.

    https://github.com/presidio-v/presidio-hardened-x402/blob/main/ARCHITECTURE.md — components, payment-flow pipeline, and trust boundaries; linked from the README.


    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.

    https://github.com/presidio-v/presidio-hardened-x402/blob/main/SECURITY.md documents the security controls, per-version threat model, and reporting process; ARCHITECTURE.md#trust-boundaries states the trust boundaries; REPO/blob/main/PRESIDIO-REQ.md carries the full threat model and design rationale.


    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.

    https://github.com/presidio-v/presidio-hardened-x402/blob/main/README.md "Quick Start" (before/after example) plus docs/quickstarts/ (Coinbase CDP, LangChain, CrewAI).


    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.

    Docs track the current release line (v0.9.x); per-version roadmap and hand-written CHANGELOG.md are kept in sync with each release.


    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 displayed and hyperlinked on the https://github.com/presidio-v/presidio-hardened-x402/blob/main/README.md front page (added in PR #90).


  • 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.

    We care deeply about persons with disabilities and support accessibility best practices wherever reasonable to do so.


    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.

    The software is a security middleware, not a consumer product.


  • 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.

    No passwords are stored.


 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]

    https://github.com/presidio-v/presidio-hardened-x402/blob/main/SECURITY.md#supported-versions states which versions are supported and for how long; REPO/blob/main/SEMVER.md documents the upgrade path and what counts as a breaking change.


 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.


  • 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]

    https://github.com/presidio-v/presidio-hardened-x402/blob/main/SECURITY.md#reporting-a-vulnerability — reporters are credited by name in the published advisory and the CHANGELOG entry unless they request anonymity.


    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.

    https://github.com/presidio-v/presidio-hardened-x402/blob/main/SECURITY.md#reporting-a-vulnerability — private GitHub Security Advisory intake, acknowledgement within 5 business days, patch target within 30 days.


 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.

    https://github.com/presidio-v/presidio-hardened-x402/blob/main/CONTRIBUTING.md#style names ruff as the required style/lint tool; config in pyproject.toml.


    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).

    ruff check and ruff format --check run in CI on every PR (FLOSS enforcement).


  • 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).

    Pure-Python package; no compiler/linker, so CC/CFLAGS/LDFLAGS do not apply.


    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.

    Pure Python; no compiled artefacts, so there is no separable debug information.


    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.

    No recursive make/subdirectory build.


    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.

    Wheels/sdists are built via the standard PEP 517 flow against a fully pinned dependency graph (uv.lock) on GitHub-hosted runners with SHA-pinned Actions. We do not yet claim bit-for-bit reproducible/hermetic builds — that is a stretch target beyond the SLSA L3 baseline we ship — but the build is deterministic from pinned sources.


  • 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.

    Standard install from PyPI: pip install presidio-hardened-x402 (also uv).


    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]

    Standard install from PyPI: pip install presidio-hardened-x402 (also uv).


    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.

    https://github.com/presidio-v/presidio-hardened-x402/blob/main/CONTRIBUTING.md#local-verification — python -m venv .venv && .venv/bin/pip install -e ".[dev]" installs everything needed to build and test.


  • 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.

    Dependencies are listed machine-readably in https://github.com/presidio-v/presidio-hardened-x402/blob/main/pyproject.toml and fully pinned in uv.lock; a CycloneDX SBOM is generated per release in CI.


    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.

    All reused components are standard PyPI packages installed via pip/uv (no vendored copies); Dependabot tracks updates.


    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.

    All reused components are standard PyPI packages installed via pip/uv (no vendored copies); Dependabot tracks updates.


    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]

    Dependencies are kept current (Dependabot + dependency floors), the public API is tracked in SEMVER.md, and the code does not rely on deprecated FLOSS functions where alternatives exist.


  • 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.

    GitHub Actions runs the full pytest suite on every push and pull request, across Python 3.10–3.13, plus the partner conformance suite — see https://github.com/presidio-v/presidio-hardened-x402/blob/main/.github/workflows/ci.yml. Each run produces a pass/fail report visible on the commit and PR (Checks tab), and a failure blocks merge via branch protection.


    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 contribution policy requires a regression test with every bug fix ("Bug fixes must include a regression test that fails before the fix and passes after it" — https://github.com/presidio-v/presidio-hardened-x402/blob/main/CONTRIBUTING.md#tests). This is applied in practice: e.g. the replay-fingerprint precision collision fix (PR #89) added a TestCanonicalAmount class plus a high-precision collision regression test. Well over 50% of bugs fixed in the last six months have accompanying regression tests.


    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.

    The FLOSS test suite (pytest + pytest-cov) is run in CI with --cov-fail-under=90, and the same floor is set in pyproject.toml ([tool.coverage.report] fail_under = 90). Statement coverage is therefore held at ≥90%, above the 80% threshold, and a drop below the floor fails the build.


  • 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]

    There is a formal written policy that new functionality must ship with tests: "Test policy: any change that adds or modifies functionality must ship with tests in the same pull request" — https://github.com/presidio-v/presidio-hardened-x402/blob/main/CONTRIBUTING.md#tests. It is enforced in review and by the coverage gate.


    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 in the contribution instructions themselves (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.

    Rule sets E, F, W, I, N, UP, S, B, A, C4, SIM, TCH — well beyond defaults, includes bandit security rules (S). Only S101, S603, S607 are excluded, with rationale.


 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 library applies established secure design principles:

    • Fail-safe defaults / secure by default: the payment pipeline fails closed (any control that raises blocks the payment), and PII redaction is on by default (pii_action="redact").
    • Least privilege: the library never holds wallet signing keys — PaymentSigner is an abstract protocol, so key custody stays with the caller; evidence-signing keys are supplied by the deployment, never embedded.
    • Complete mediation: every payment is checked against spending policy, replay fingerprinting, and PII filtering before it can leave the process toward the network or chain (pre-execution enforcement).
    • Defense in depth: independent controls (policy, replay guard, PII filter, multi-party authorization, HMAC-chained audit log, signed evidence) each mitigate a distinct threat; remote screening keeps a local regex backstop so a remote failure fails safe.
    • Least common mechanism / input validation: all payment metadata from the calling agent is treated as untrusted and validated (e.g. canonicalisation byte-stability contracts, action_ref rejecting empty entity sets).
    • Economy of mechanism: cryptography uses vetted standard-library / cryptography primitives (SHA-256, HMAC-SHA256, ed25519) rather than bespoke implementations.

    See https://github.com/presidio-v/presidio-hardened-x402/blob/main/ARCHITECTURE.md and https://github.com/presidio-v/presidio-hardened-x402/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.

    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.

    No SHA-1 and no CBC-mode dependency in default paths.


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    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]

    The library does not expose a user-facing cryptographic-algorithm negotiation surface; its integrity and signature primitives are pinned to current strong choices (SHA-256 and HMAC-SHA256 for digests/fingerprinting/audit chaining, ed25519 for evidence signatures). Algorithm agility is instead provided at the record-format layer: the emitted evidence and decision records are explicitly versioned (payment-decision@1, evidence-ref@1, capability-grant@1) and the canonicalisation/digest functions are byte-stability contracts, so replacing an algorithm is a versioned format change (bump the record version) rather than a runtime switch. Runtime crypto-suite negotiation does not apply to this library's design.


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    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]

    All keys and secrets are supplied to the library from outside the source tree and can be rotated without any code change. The replay-fingerprint and audit-chain keys are read from environment variables (PRESIDIO_X402_FINGERPRINT_KEY, PRESIDIO_X402_CHAIN_KEY); evidence-signing keys and verification trust stores are provided by the deployment as separate files/config, never embedded in code. None are hard-coded, none live in the config that carries non-secret settings, and the log sink scrubs key and token material (install_log_redaction) so credentials do not leak into logs. Because the library is pure Python configured at runtime, updating or replacing any credential requires no recompilation.


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    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]

    All network communication the library performs uses TLS (HTTPS). The hosted-screening client and the remote audit sinks (S3, Splunk HEC, Datadog) enforce TLS with certificate verification; there is no plaintext HTTP, FTP, telnet, or legacy SSL/TLS path, and none can be enabled by configuration. On a remote-screening failure the library falls back to the local regex backstop rather than to an insecure channel, so it fails safe. The abstract PaymentSigner and the payment rail itself are supplied by the integrator and are out of the library's transport scope.


    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]

    Where the library uses TLS (hosted-screening client and the remote audit sinks), it relies on the platform TLS stack via the hardened HTTP client reused from presidio-hardened-requests, which negotiates TLS 1.2 or later. No SSLv3/TLS 1.0/1.1 path is offered or configurable.


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    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.

    Where the library uses TLS (hosted-screening client and remote audit sinks), certificate verification is on by default via the hardened HTTP client reused from presidio-hardened-requests; verification is never disabled and there is no verify=False path or configuration option to turn it off.


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    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 library uses the hardened HTTP client (reused from presidio-hardened-requests), which completes the TLS handshake and certificate verification before any request headers or body are transmitted; verification is on by default and cannot be disabled. Authorization/API-key headers to the hosted-screening service and audit sinks are therefore only sent over an already-verified TLS connection. On verification failure the request fails closed and the local regex backstop runs instead, so no private header is sent over an unverified channel.


  • Secure release


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    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.

    Releases are cryptographically signed and the process for obtaining/verifying keys is documented at https://github.com/presidio-v/presidio-hardened-x402/blob/main/SECURITY.md#obtaining-the-public-signing-keys: Sigstore build provenance (gh attestation verify), SSH-signed git tags with the public key in https://github.com/presidio-v/presidio-hardened-x402/blob/main/allowed_signers, and PEP 740 attestations on PyPI.


    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]

    Every release is a git tag, SSH-signed with the org key and shown as Verified on GitHub.


  • Other security issues


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    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.

    All payment metadata arriving from the calling agent is treated as untrusted and validated before use (e.g. action_ref rejects empty entity-type sets; canonicalisation enforces byte-stability contracts). See ARCHITECTURE.md#trust-boundaries.


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    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).

    TLS enforced on all network egress; bounded audit buffers; import-time log redaction of secrets; SHA-pinned GitHub Actions; digest-pinned Docker base and hash-pinned spaCy model.


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    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.

    The security assurance case is documented at https://github.com/presidio-v/presidio-hardened-x402/blob/main/ASSURANCE.md. It contains all four required parts: (1) the threat model — assets, adversaries (compromised/overspending agent, replay, spoofed SLO trigger, audit tampering, metadata leakage) and their mitigations, with per-version tables in SECURITY.md and full rationale in PRESIDIO-REQ.md; (2) clear identification of trust boundaries (agent→library untrusted input, library→chain irreversible egress, library→screening/audit network egress, out-of-scope signing-key custody); (3) an argument that secure design principles are applied (fail-safe defaults, complete mediation, least privilege, defense in depth, economy of mechanism); and (4) an argument that common implementation weakness classes are countered (input validation/injection, memory safety, crypto misuse, hard-coded secrets, insecure network/SSRF, replay, audit tampering, unsafe deserialization, vulnerable dependencies), each mapped to a control and reinforced by CodeQL, bandit, Scorecard, and an independent v0.8.0 security review.


 Analysis 2/2 ●

  • Static code analysis


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    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's security query suite and bandit both target common vulnerability classes; ruff's S rule set adds a third layer in-line.


  • Dynamic code analysis


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    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.

    Pure Python; no memory-unsafe language in the codebase.



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 Vladimir Stantchev and the OpenSSF Best Practices badge contributors.

Project badge entry owned by: Vladimir Stantchev.
Entry created on 2026-07-20 21:44:26 UTC, last updated on 2026-07-21 20:55:28 UTC. Last achieved passing badge on 2026-07-20 22:20:31 UTC.