Native Signing of Build Artifacts
<!-- The first section "Release notes" is required if you want to have your release post blog MR auto generated. Currently in BETA, details on the **release post item generator** can be found in the handbook: https://about.gitlab.com/handbook/marketing/blog/release-posts/#release-post-item-generator and this video: https://www.youtube.com/watch?v=rfn9ebgTwKg. The next four sections: "Problem to solve", "Intended users", "User experience goal", and "Proposal", are strongly recommended in your first draft, while the rest of the sections can be filled out during the problem validation or breakdown phase. However, keep in mind that providing complete and relevant information early helps our product team validate the problem and start working on a solution. -->
### Release notes
<!-- What is the problem and solution you're proposing? This content sets the overall vision for the feature and serves as the release notes that will populate in various places, including the [release post blog](https://about.gitlab.com/releases/categories/releases/) and [Gitlab project releases](https://gitlab.com/gitlab-org/gitlab/-/releases). " -->
### Problem to solve
<!-- What problem do we solve? Try to define the who/what/why of the opportunity as a user story. For example, "As a (who), I want (what), so I can (why/value)." -->
As a Developer, I want my build artifacts to be signed automatically.
As a DevOps Engineer, I want a signed attestation produced automatically so others can verify the provenance of my software.
As a Compliance Manager, I want to be assured that signatures are non-falsifiable.
As an Infrastructure Security Engineer, I want to validate signatures before running build artifacts in my environment.
### Intended users
<!-- Who will use this feature? If known, include any of the following: types of users (e.g. Developer), personas, or specific company roles (e.g. Release Manager). It's okay to write "Unknown" and fill this field in later.
Personas are described at https://about.gitlab.com/handbook/product/personas/
* [Parker (Product Manager)](https://about.gitlab.com/handbook/product/personas/#parker-product-manager)
* [Delaney (Development Team Lead)](https://about.gitlab.com/handbook/product/personas/#delaney-development-team-lead)
* [Presley (Product Designer)](https://about.gitlab.com/handbook/product/personas/#presley-product-designer)
* [Sasha (Software Developer)](https://about.gitlab.com/handbook/product/personas/#sasha-software-developer)
* [Priyanka (Platform Engineer)](https://about.gitlab.com/handbook/product/personas/#priyanka-platform-engineer)
* [Sidney (Systems Administrator)](https://about.gitlab.com/handbook/product/personas/#sidney-systems-administrator)
* [Rachel (Release Manager)](https://about.gitlab.com/handbook/product/personas/#rachel-release-manager)
* [Simone (Software Engineer in Test)](https://about.gitlab.com/handbook/product/personas/#simone-software-engineer-in-test)
* [Allison (Application Ops)](https://about.gitlab.com/handbook/product/personas/#allison-application-ops)
* [Ingrid (Infrastructure Operator)](https://about.gitlab.com/handbook/product/personas/#ingrid-infrastructure-operator)
* [Dakota (Application Development Director)](https://about.gitlab.com/handbook/product/personas/#dakota-application-development-director)
* [Dana (Data Analyst)](https://about.gitlab.com/handbook/product/personas/#dana-data-analyst)
* [Eddie (Content Editor)](https://about.gitlab.com/handbook/product/personas/#eddie-content-editor)
* [Amy (Application Security Engineer)](https://about.gitlab.com/handbook/product/personas/#amy-application-security-engineer)
* [Isaac (Infrastructure Engineer)](https://about.gitlab.com/handbook/product/personas/#isaac-infrastructure-security-engineer)
* [Alex (Security Operations Engineer)](https://about.gitlab.com/handbook/product/personas/#alex-security-operations-engineer)
* [Cameron (Compliance Manager)](https://about.gitlab.com/handbook/product/personas/#cameron-compliance-manager)
-->
* [Sasha (Software Developer)](https://about.gitlab.com/handbook/product/personas/#sasha-software-developer)
* [Rachel (Release Manager)](https://about.gitlab.com/handbook/product/personas/#rachel-release-manager)
* [Ingrid (Infrastructure Operator)](https://about.gitlab.com/handbook/product/personas/#ingrid-infrastructure-operator)
* [Isaac (Infrastructure Engineer)](https://about.gitlab.com/handbook/product/personas/#isaac-infrastructure-security-engineer)
* [Cameron (Compliance Manager)](https://about.gitlab.com/handbook/product/personas/#cameron-compliance-manager)
### User experience goal
<!-- What is the single user experience workflow this problem addresses?
For example, "The user should be able to use the UI/API/.gitlab-ci.yml with GitLab to <perform a specific task>"
https://about.gitlab.com/handbook/product/ux/ux-research-training/user-story-mapping/ -->
All build artifacts produced by GitLab-hosted SaaS Runners are signed automatically and by default.
### Proposal
<!-- How are we going to solve the problem? Try to include the user journey! https://about.gitlab.com/handbook/journeys/#user-journey -->
1. A new CI variable `SIGN_ARTIFACTS: true` will be created to allow users to opt in to signing their build artifacts. This is done to avoid a breaking change for any users who may have pipeline validation that checks the number of files produced by their pipeline. This variable will be deprecated and removed in %17.0 when signing will be turned on by default.
1. Any build artifact produced by a GitLab SaaS Runner will be signed automatically without requiring users to make any changes to their `.gitlab-ci.yml` file.
1. GitLab CI/CD jobs will not have access to the signing key or the token used to generate the signing key. All signing must be done in code outside the reach of the job.
1. The token used to generate the signing key must only be possible to generate with the correct claims when generated by a GitLab Runner. Attempting to generate a token in any other way must result in an invalid signature due to incorrect claims in the token metadata.
1. Ideally we would use the OIDC identify of the GitLab Runner itself rather than a user's identity; however, this requirement is somewhat optional and can be skipped if it cannot reasonably be met due to technical constraints.
1. The [attestation file](https://docs.gitlab.com/ee/ci/runners/configure_runners.html#artifact-attestation) that we currently generate when `RUNNER_GENERATE_ARTIFACTS_METADATA: true` will be deprecated and scheduled for removal in %17.0.
1. If `SIGN_ARTIFACTS: true` then we will automatically generate a new `.provenance` file and store it as a build artifact containing the signature.
1. The format will be updated to use [v1 of the in-toto specification](https://github.com/in-toto/attestation/blob/main/spec/v1/).
1. The format will adhere to [SLSA v1](https://slsa.dev/provenance/v1-rc1#schema).
1. The format of the `.provenance` file should match https://github.com/sigstore/cosign/blob/main/specs/SIGNATURE_SPEC.md.
1. Additionally, we will begin adding the required envelope to the generated attestation per https://github.com/in-toto/attestation/blob/main/spec/v1/envelope.md
1. The JSON that we currently generate as our attestation/provenance file will be base64 encoded and will become the value of the `payload` attribute.
1. The `payloadType` attribute is static and should always be set to `application/vnd.in-toto+json`
1. The `signatures` attribute will contain the signature of the `payload`
The resulting attestation/provenance file should match this format:
```json
{
"payloadType": "application/vnd.in-toto+json",
"payload": "<Base64(SERIALIZED_BODY)>",
"signatures": [{
"keyid": "<KEYID>",
"sig": "<Base64(SIGNATURE)>"
}]
}
```
### Further details
<!-- Include use cases, benefits, goals, or any other details that will help us understand the problem better. -->
### Permissions and Security
<!-- What permissions are required to perform the described actions? Are they consistent with the existing permissions as documented for users, groups, and projects as appropriate? Is the proposed behavior consistent between the UI, API, and other access methods (e.g. email replies)?
Consider adding checkboxes and expectations of users with certain levels of membership https://docs.gitlab.com/ee/user/permissions.html
* [ ] Add expected impact to members with no access (0)
* [ ] Add expected impact to Guest (10) members
* [ ] Add expected impact to Reporter (20) members
* [ ] Add expected impact to Developer (30) members
* [ ] Add expected impact to Maintainer (40) members
* [ ] Add expected impact to Owner (50) members
Please consider performing a threat model for the code changes that are introduced as part of this feature. To get started, refer to our Threat Modeling handbook page https://about.gitlab.com/handbook/security/threat_modeling/#threat-modeling.
Don't hesitate to reach out to the Application Security Team (`@gitlab-com/gl-security/appsec`) to discuss any security concerns.
-->
### Documentation
<!-- See the Feature Change Documentation Workflow https://docs.gitlab.com/ee/development/documentation/workflow.html#for-a-product-change
* Add all known Documentation Requirements in this section. See https://docs.gitlab.com/ee/development/documentation/workflow.html
* If this feature requires changing permissions, update the permissions document. See https://docs.gitlab.com/ee/user/permissions.html -->
### Availability & Testing
<!-- This section needs to be retained and filled in during the workflow planning breakdown phase of this feature proposal, if not earlier.
What risks does this change pose to our availability? How might it affect the quality of the product? What additional test coverage or changes to tests will be needed? Will it require cross-browser testing?
Please list the test areas (unit, integration and end-to-end) that needs to be added or updated to ensure that this feature will work as intended. Please use the list below as guidance.
* Unit test changes
* Integration test changes
* End-to-end test change
See the Quality Engineering quad planning and test planning processes and reach out to your counterpart Software Engineer in Test for assistance.
Quad Planning: https://about.gitlab.com/handbook/engineering/quality/quality-engineering/quad-planning
Test Planning: https://about.gitlab.com/handbook/engineering/quality/quality-engineering/test-engineering/#test-planning -->
### Available Tier
<!-- This section should be used for setting the appropriate tier that this feature will belong to. Pricing can be found here: https://about.gitlab.com/pricing/
* Free
* Premium/Silver
* Ultimate/Gold
-->
~"GitLab Free"
### Feature Usage Metrics
<!-- How are you going to track usage of this feature? Think about user behavior and their interaction with the product. What indicates someone is getting value from it?
Create tracking issue using the Snowplow event tracking template. See https://gitlab.com/gitlab-org/gitlab/-/blob/master/.gitlab/issue_templates/Snowplow%20event%20tracking.md
-->
### What does success look like, and how can we measure that?
<!--
Define both the success metrics and acceptance criteria. Note that success metrics indicate the desired business outcomes, while acceptance criteria indicate when the solution is working correctly. If there is no way to measure success, link to an issue that will implement a way to measure this.
Create tracking issue using the Snowplow event tracking template. See https://gitlab.com/gitlab-org/gitlab/-/blob/master/.gitlab/issue_templates/Snowplow%20event%20tracking.md
-->
### What is the type of buyer?
<!-- What is the buyer persona for this feature? See https://about.gitlab.com/handbook/product/personas/buyer-persona/
In which enterprise tier should this feature go? See https://about.gitlab.com/handbook/product/pricing/#three-tiers -->
### Is this a cross-stage feature?
<!-- Communicate if this change will affect multiple Stage Groups or product areas. We recommend always start with the assumption that a feature request will have an impact into another Group. Loop in the most relevant PM and Product Designer from that Group to provide strategic support to help align the Group's broader plan and vision, as well as to avoid UX and technical debt. https://about.gitlab.com/handbook/product/#cross-stage-features -->
### What is the competitive advantage or differentiation for this feature?
### Links / references
<!-- Label reminders - you should have one of each of the following labels.
Use the following resources to find the appropriate labels:
- Use only one tier label choosing the lowest tier this is intended for
- https://gitlab.com/gitlab-org/gitlab/-/labels
- https://about.gitlab.com/handbook/product/categories/features/
-->
<!-- triage-serverless v3 PLEASE DO NOT REMOVE THIS SECTION -->
*This page may contain information related to upcoming products, features and functionality.
It is important to note that the information presented is for informational purposes only, so please do not rely on the information for purchasing or planning purposes.
Just like with all projects, the items mentioned on the page are subject to change or delay, and the development, release, and timing of any products, features, or functionality remain at the sole discretion of GitLab Inc.*
<!-- triage-serverless v3 PLEASE DO NOT REMOVE THIS SECTION -->
epic