Badge Status for JSON for Modern C++

Projects that follow the best practices below will be able to voluntarily self-certify and show that they've achieved a Core Infrastructure Initiative (CII) 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). Feedback is welcome via the GitHub site as issues or pull requests There is also a mailing list for general discussion.

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  • Identification

    What is the human-readable name of the project?
    Note that other projects may use the same name.
    What is a brief description of the project?

    JSON for Modern C++ aims at making JSON a first class datatype in C++ by including a single header file. The only requirement is a C++11 compiler, and the code is reported to compile on all major systems. Since 2013, the library is used in numerous projects and has received over 3000 stars on Github.

    What is the URL for the project (as a whole)?
    What is the URL for the version control repository (it may be the same as the project URL)?
    What programming language(s) are used to implement the project?
    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".

    What is the Common Platform Enumeration (CPE) name for the project (if it has one)?
    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).

    File provides an overview of the goals of the project and basic usage patterns.

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

    The project uses Github to report bugs and feature requests via its issue functionality. File summarizes all information on how to contribute to the project.

    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?)

    Projects on GitHub by default use issues and pull requests, as encouraged by documentation such as

    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]

  • FLOSS License

    What license(s) is the project released under?
    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)".

    The software 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 MIT license is approved by the Open Source Initiative (OSI).

    It is SUGGESTED that any required license(s) 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 MIT license is approved by the Open Source Initiative (OSI).

    The project MUST post license(s) in a standard location. (URL required) [license_location]
    E.g., as a top-level file named LICENSE or COPYING. License filenames MAY be followed by an extension such as ".txt" or ".md".

  • Documentation

    The project MUST provide basic documentation for the software. [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.

    Beyond the basic usage patterns in file, a more detailed documentation can be found in

    The project MUST include reference documentation that describes its external interface (both input and output). [documentation_interface]
    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), 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.

    The complete public API documentation is available at The private API is documented in the source code, and a similar hypertext documentation can be generated by running Doxygen locally.

  • Other

    The project sites (website, repository, and download URLs) MUST support HTTPS using TLS. [sites_https]
    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 are using GitHub pages with custom domains, you MAY use a content delivery network (CDN) as a proxy to support HTTPS, such as described in the blog post "Secure and fast GitHub Pages with CloudFlare", to satisfy this criterion. If you support HTTP, we urge you to redirect the HTTP traffic to HTTPS.

    Github uses HTTPS only.

    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 include 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 is in English, and the project accepts bug reports and comments in English.

Other general comments about the project:

 Change Control

  • 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 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).

    There is a development branch "develop" for interim development from which release branches are created.

    It is SUGGESTED that common distributed version control software be used (e.g., git). [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.

  • Version numbering

    The project 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).

    See the releases list at

    It is SUGGESTED that the Semantic Versioning (SemVer) format be used for releases. [version_semver]
    Other version numbering schemes, such as commit IDs (such as git commit id or mercurial changeset id) or date-based schemes like YYYYMMDD, MAY be used as version numbers, since they are unique. Some alternatives can cause problems, because users may not be able to easily determine if they are up-to-date. SemVer may be less helpful 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).

    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]

    Every release is tagged. See for a list of 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:

    The release notes MUST identify every publicly known vulnerability that is fixed in each new release. This is "N/A" if there are no release notes or there have been no publicly known vulnerabilities. [release_notes_vulns]

    We intend to do that, though we have not had any need to do that yet.


  • 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]

    The project uses Github's issue tracker at

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

    The project uses Github's issue tracker at

    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]

    All tickets reported at received a timely answer.

    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).

    All tickets reported at received a timely answer.

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

    The project uses Github's issue tracker at which implements are search functionality.

  • Vulnerability reporting process

    The project MUST publish the process for reporting vulnerabilities on the project site. (URL required) [vulnerability_report_process]
    E.g., a clearly designated mailing address on https://PROJECTSITE/security, often in the form This MAY be the same as its bug reporting process. Vulnerability reports MAY always be public, but many projects have a private vulnerability reporting mechanism.

    So far, no vulnerabilities are known. However, future vulnerabilities would be reported in the file and in the release notes when fixed.

    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).

    File contains a section on private reports.

    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).

    No external reports so far, so this is vacuously true.


  • Working build system

    If the software 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 there is no need to build anything to use the software after its source code is modified, select "not applicable" (N/A).

    The software is a single C++ header and needs no special build system. For the unit tests, the repository contains a Makefile and a CMakeLists file Furthermore, files and contain build scripts for Travis ( and AppVeyor (, respectively.

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

    The project is a single header that can be built with any C++ compiler. No further software is required to build. See for more information.

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

    The project is a single header that can be built with any C++ compiler, including FLOSS versions like the GNU Compiler Collection. No further software is required to build. See for more information.

  • Automated test suite

    The project MUST have at least one automated test suite that is publicly released as FLOSS (this test suite may be maintained as a separate FLOSS project). [test]
    The project MAY have multiple automated test suites (e.g., one that runs quickly, vs. another that is more thorough but requires special equipment).

    The project is tested with a unit test suite (see which is part of the project. The test suite is released under the same license. The test suite uses Catch ( which is released under the Boost Software License 1.0.

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

    The unit tests can be built and executed with a Makefile/CMake target and is described in the README file

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

    The unit tests cover 100% of the functions and lines of the library, see The authors currently work on improving the branch coverage of the tests.

    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]

    Continuous integration is used for OS X and Linux with Travis ( and Windows with AppVeyor (

  • New functionality testing

    The project MUST have a general policy (formal or not) that as major new functionality is added, 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."

    File asks contributors to add unit tests for added functionality.

    The project MUST have evidence that such tests are being added in the most recent major changes to the project. [tests_are_added]
    Major functionality would typically be mentioned in the ChangeLog. (Perfection is not required, merely evidence that tests are typically being added in practice.)

    The unit test coverage is checked with every commit and especially reported with every pull request, see

    It is SUGGESTED that this policy on adding tests 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.

    File asks contributors to add unit tests for added functionality.

  • 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.

    The test suite which covers 100% of the library is built with extensive compiler warning flags, see

    The project MUST address warnings. [warnings_fixed]
    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).

    The development works hard to fix all warnings, and there also have been several external pull requests with fixes.

    It is SUGGESTED that projects be maximally strict with warnings, but this is not always practical. [warnings_strict]

    The project is compiled with the following warning flags: -Wall -Wextra -pedantic -Weffc++ -Wcast-align -Wcast-qual -Wno-ctor-dtor-privacy -Wdisabled-optimization -Wformat=2 -Winit-self -Wmissing-declarations -Wmissing-include-dirs -Wold-style-cast -Woverloaded-virtual -Wredundant-decls -Wshadow -Wsign-conversion -Wsign-promo -Wstrict-overflow=5 -Wswitch -Wundef -Wno-unused -Wnon-virtual-dtor -Wreorder -Wdeprecated -Wno-float-equal - see file


  • Secure development knowledge

    The project MUST have at least one primary developer who knows how to design secure software. [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 whitelists (inputs should typically be checked to determine if they are valid before they are accepted; this validation should use whitelists (which only accept known-good values), not blacklists (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.

    Niels Lohmann is the primary developer. He is aware of the design principles - however, a lot of them are not directly applicable to the library. Nevertheless, the shall be followed in the future.

    At least one of the 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.

    The greatest source of vulnerability for the library is the parsing of user input. To detect and mitigate errors, (1) the test suite covers 100% of the code, (2) important invariants are proven or checked with assertions, and (3) regular fuzz testing is executed.

  • Good cryptographic practices

    Note that some software does not need to directly use cryptographic capabilities. A "project security mechanism" is a security mechanism provided by the delivered project's software.

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

    If the project software 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 functionality that depends on cryptography MUST be implementable using FLOSS. [crypto_floss]

    The project security mechanisms MUST use default keylengths that at least meet the NIST minimum requirements through the year 2030 (as stated in 2012). [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 for a comparison of keylength recommendations from various organizations. The software MUST be configurable so that it will reject smaller keylengths. 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). A "project security mechanism" is a security mechanism provided by the delivered project's software.

    The default project security mechanisms MUST NOT depend on cryptographic algorithms/modes that are broken (e.g., MD4, MD5, single DES, RC4, Dual_EC_DRBG, or ECB mode). [crypto_working]

    The project security mechanisms SHOULD NOT by default depend on cryptographic algorithms with known serious weaknesses (e.g., SHA-1). [crypto_weaknesses]

    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]

    If passwords are stored for authentication of external users, the project MUST store them as iterated hashes with a per-user salt by using a key stretching (iterated) algorithm (e.g., PBKDF2, Bcrypt or Scrypt). [crypto_password_storage]

    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 not cryptographically secure. [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.

  • 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.

    Uses https.

    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.

    Uses https.

  • Publicly-known vulnerabilities fixed

    There MUST be no unpatched vulnerabilities of medium or high 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 medium to high severity if its CVSS 2.0 base score is 4 or higher. 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.

    No such vulnerabilities at this time.

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

    No such vulnerabilities at this time.

  • Other security

    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.

    No such information is leaked.


  • Static code analysis

    At least one static code analysis tool 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). Examples of such static code analysis tools include cppcheck, clang static analyzer, FindBugs (including FindSecurityBugs), PMD, Brakeman, Coverity Quality Analyzer, and HP 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. The SWAMP is a no-cost platform for assessing vulnerabilities in software using a variety of tools. If there are no FLOSS static analysis tools available for the implementation language(s) used, select 'N/A'.

    Cppcheck ( is routenely used to perform static analysis, see

    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]

    Cppcheck ( is routenely used to perform static analysis, see

    All medium and high 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 medium to high severity if its CVSS 2.0 is 4 or higher.

    So far, no vulnerability has been discovered, so this point is satisfied.

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

    cppcheck is run with every commit (see Travis file It is run with "--enable=warning" and "--error-exitcode=1" to fail the build in case of a finding.

  • Dynamic 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.

    Valgrind is run with every commit (see Travis file and will fail the build in case of a finding. Fuzz tests are run with every release.

    It is SUGGESTED that if the software is application-level 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 with a mechanism to detect memory safety problems such as buffer overwrites. [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. If the software is not application-level, or is not in a memory-unsafe language, then this criterion is automatically met.

    Memory safety is checked with Valgrind with each commit (see and errors will break the build. Fuzz testing is possible with "make fuzz_testing" (using american fuzzy lop, and is executed routinely.

    It is SUGGESTED that the software include many run-time assertions that are checked during dynamic analysis. [dynamic_analysis_enable_assertions]

    The invariant of the main class is checked with assertions (see All pointer access is checked with an assertion. All functions with potential undefined behavior contain an assertion to detect invalid use.

    All medium and high severity exploitable vulnerabilities discovered with dynamic code analysis MUST be fixed in a timely way after they are confirmed. [dynamic_analysis_fixed]
    A vulnerability is medium to high severity if its CVSS 2.0 base score is 4. If you are not running dynamic code analysis and thus have not found any vulnerabilities in this way, choose "not applicable" (N/A).

    So far, no vulnerability has been discovered, so this point is satisfied.


These are criteria we intend to add in the near future, but are not currently required for a badge. This grace period allows projects to update to changed criteria and retain their badge as best practices improve.

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

The project is a single C++ header file - there is no commonly-used convention on how to install such software. The closest one can get toward this is to use the install targets in the shipped CMake file.

(Future criterion) It is SUGGESTED that the project have a reproducible build. [build_reproducible]
A reproducible build means that multiple parties can independently redo 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 "N/A". In some cases, this can resolved by forcing some sort order. JavaScript developers may consider using npm shrinkwrap and webpack OccurenceOrderPlugin. GCC and clang users may find the -frandom-seed option useful. The build environment (including the toolset) can often be defined for external parties by specifying the cryptographic hash of a specific container or virtual machine that they can use for rebuilding. The reproducible builds project has documentation on how to do this.

The project is built automatically with Travis ( and AppVeyor ( for each commit.

(Future criterion) The project SHOULD NOT use unencrypted network communication protocols (such as HTTP and telnet) if there an encrypted equivalent (e.g., HTTPS/TLS and SSH), unless the user specifically requests or configures it. [crypto_used_network]

The library does not have network access nor it is planned to add network access.

(Future criterion) The project SHOULD, if it supports TLS, support at least TLS version 1.2. Note that the predecessor of TLS was called SSL. [crypto_tls12]

The library does not have network access nor it is planned to add network access.

(Future criterion) The project MUST, if it supports TLS, perform TLS certificate verification by default when using TLS, including on subresources. [crypto_certificate_verification]

The library does not have network access nor it is planned to add network access.

(Future criterion) The project SHOULD, if it supports TLS, perform certificate verification before sending HTTP headers with private information (such as secure cookies). [crypto_verification_private]

The library does not have network access nor it is planned to add network access.

(Future criterion) It is SUGGESTED that the project website, repository (if accessible via the web), and download site (if separate) include key hardening headers with nonpermissive values. [hardened_site]
Note that GitHub is known to meet this. Sites such as can quickly check this. The key hardening headers are: Content Security Policy (CSP), HTTP Strict Transport Security (HSTS), X-Content-Type-Options (as "nosniff"), X-Frame-Options, and X-XSS-Protection.

The project uses Github which is known to meet this.

(Future criterion) It is SUGGESTED that hardening mechanisms be used so 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).

The code is constantly tested and checked with static analysis tools. Part of the software's correctness has been proved manually (see comments in the code, search for "Proof").

This data is available under the Creative Commons Attribution version 3.0 license (CC-BY-3.0) per the Core Infrastructure Initiative terms of use. All are free to share and adapt the data, but must give appropriate credit. Please credit Niels Lohmann and the CII Best Practices badge contributors.

Project badge entry owned by: Niels Lohmann.
Entry created on 2016-08-15 07:12:13 UTC (7 months ago), last updated on 2016-08-18 16:38:07 UTC (7 months ago). Last achieved passing badge on 2016-08-18 16:38:07 UTC (7 months ago).