init attest build provenance

2025-12-13 10:52:28 +00:00 · 2024-02-22 08:29:05 -08:00 · 2024-02-22 08:29:05 -08:00 · 381fca5703
commit 381fca5703
parent 1a4323c55b
45 changed files with 2789 additions and 238 deletions
--- a/.eslintignore
+++ b/.eslintignore
@ -2,3 +2,4 @@ lib/
 dist/
 node_modules/
 coverage/
+packages/
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@ -5,31 +5,36 @@ on:
  push:
    branches:
      - main
+      - 'releases/*'

-permissions:
-  contents: read
+permissions: {}

 jobs:
  test-typescript:
    name: TypeScript Tests
    runs-on: ubuntu-latest
+    permissions:
+      contents: read

    steps:
      - name: Checkout
        id: checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1

      - name: Setup Node.js
        id: setup-node
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@b39b52d1213e96004bfcb1c61a8a6fa8ab84f3e8 # v4.0.1
        with:
-          node-version-file: .node-version
+          node-version: 18
          cache: npm

      - name: Install Dependencies
        id: npm-ci
        run: npm ci

+      - name: Build @actions/attest
+        run: npm run build --workspace packages/attest
+
      - name: Check Format
        id: npm-format-check
        run: npm run format:check
@ -37,26 +42,29 @@ jobs:
      - name: Lint
        id: npm-lint
        run: npm run lint
+      # - name: Test
+      #   id: npm-ci-test
+      #   run: npm run ci-test

-      - name: Test
-        id: npm-ci-test
-        run: npm run ci-test
-
-  test-action:
-    name: GitHub Actions Test
+  test-attest-provenance:
+    name: Test attest-provenance action
    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
+      packages: write

    steps:
      - name: Checkout
        id: checkout
-        uses: actions/checkout@v4
-
-      - name: Test Local Action
-        id: test-action
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+      - name: Run attest-provenance
+        id: attest-provenance
        uses: ./
        with:
-          milliseconds: 2000
+          subject-digest: 'sha256:7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32'
+          subject-name: 'subject'
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Dump output
+        run: jq < ${{ steps.attest-provenance.outputs.bundle-path }}

-      - name: Print Output
-        id: output
-        run: echo "${{ steps.test-action.outputs.time }}"
--- a/tests/index.test.ts
+++ b/tests/index.test.ts
@ -1,17 +0,0 @@
-/**
- * Unit tests for the action's entrypoint, src/index.ts
- */
-
-import * as main from '../src/main'
-
-// Mock the action's entrypoint
-const runMock = jest.spyOn(main, 'run').mockImplementation()
-
-describe('index', () => {
-  it('calls run when imported', async () => {
-    // eslint-disable-next-line @typescript-eslint/no-require-imports
-    require('../src/index')
-
-    expect(runMock).toHaveBeenCalled()
-  })
-})
--- a/tests/main.test.ts
+++ b/tests/main.test.ts
@ -1,89 +0,0 @@
-/**
- * Unit tests for the action's main functionality, src/main.ts
- *
- * These should be run as if the action was called from a workflow.
- * Specifically, the inputs listed in `action.yml` should be set as environment
- * variables following the pattern `INPUT_<INPUT_NAME>`.
- */
-
-import * as core from '@actions/core'
-import * as main from '../src/main'
-
-// Mock the action's main function
-const runMock = jest.spyOn(main, 'run')
-
-// Other utilities
-const timeRegex = /^\d{2}:\d{2}:\d{2}/
-
-// Mock the GitHub Actions core library
-let debugMock: jest.SpyInstance
-let errorMock: jest.SpyInstance
-let getInputMock: jest.SpyInstance
-let setFailedMock: jest.SpyInstance
-let setOutputMock: jest.SpyInstance
-
-describe('action', () => {
-  beforeEach(() => {
-    jest.clearAllMocks()
-
-    debugMock = jest.spyOn(core, 'debug').mockImplementation()
-    errorMock = jest.spyOn(core, 'error').mockImplementation()
-    getInputMock = jest.spyOn(core, 'getInput').mockImplementation()
-    setFailedMock = jest.spyOn(core, 'setFailed').mockImplementation()
-    setOutputMock = jest.spyOn(core, 'setOutput').mockImplementation()
-  })
-
-  it('sets the time output', async () => {
-    // Set the action's inputs as return values from core.getInput()
-    getInputMock.mockImplementation((name: string): string => {
-      switch (name) {
-        case 'milliseconds':
-          return '500'
-        default:
-          return ''
-      }
-    })
-
-    await main.run()
-    expect(runMock).toHaveReturned()
-
-    // Verify that all of the core library functions were called correctly
-    expect(debugMock).toHaveBeenNthCalledWith(1, 'Waiting 500 milliseconds ...')
-    expect(debugMock).toHaveBeenNthCalledWith(
-      2,
-      expect.stringMatching(timeRegex)
-    )
-    expect(debugMock).toHaveBeenNthCalledWith(
-      3,
-      expect.stringMatching(timeRegex)
-    )
-    expect(setOutputMock).toHaveBeenNthCalledWith(
-      1,
-      'time',
-      expect.stringMatching(timeRegex)
-    )
-    expect(errorMock).not.toHaveBeenCalled()
-  })
-
-  it('sets a failed status', async () => {
-    // Set the action's inputs as return values from core.getInput()
-    getInputMock.mockImplementation((name: string): string => {
-      switch (name) {
-        case 'milliseconds':
-          return 'this is not a number'
-        default:
-          return ''
-      }
-    })
-
-    await main.run()
-    expect(runMock).toHaveReturned()
-
-    // Verify that all of the core library functions were called correctly
-    expect(setFailedMock).toHaveBeenNthCalledWith(
-      1,
-      'milliseconds not a number'
-    )
-    expect(errorMock).not.toHaveBeenCalled()
-  })
-})
--- a/tests/wait.test.ts
+++ b/tests/wait.test.ts
@ -1,25 +0,0 @@
-/**
- * Unit tests for src/wait.ts
- */
-
-import { wait } from '../src/wait'
-import { expect } from '@jest/globals'
-
-describe('wait.ts', () => {
-  it('throws an invalid number', async () => {
-    const input = parseInt('foo', 10)
-    expect(isNaN(input)).toBe(true)
-
-    await expect(wait(input)).rejects.toThrow('milliseconds not a number')
-  })
-
-  it('waits with a valid number', async () => {
-    const start = new Date()
-    await wait(500)
-    const end = new Date()
-
-    const delta = Math.abs(end.getTime() - start.getTime())
-
-    expect(delta).toBeGreaterThan(450)
-  })
-})
--- a/action.yml
+++ b/action.yml
@ -1,24 +1,59 @@
-name: 'The name of your action here'
-description: 'Provide a description here'
-author: 'Your name or organization here'
+name: 'Attest Build Provenance'
+description: 'Generate provenance attestations for build artifacts'
+author: 'GitHub'

-# Add your action's branding here. This will appear on the GitHub Marketplace.
-branding:
-  icon: 'heart'
-  color: 'red'
-
-# Define your inputs here.
 inputs:
-  milliseconds:
-    description: 'Your input description here'
-    required: true
-    default: '1000'
-
-# Define your outputs here.
+  github-token:
+    description: >
+      The GitHub token used to make authenticated API requests.
+    default: ${{ github.token }}
+    required: false
+  subject-path:
+    description: >
+      Path to the artifact for which provenance will be generated. Must specify
+      exactly one of "subject-path" or "subject-digest".
+    required: false
+  subject-digest:
+    description: >
+      Digest of the subject for which provenance will be generated. Must be in
+      the form "algorithm:hex_digest" (e.g. "sha256:abc123..."). Must specify
+      exactly one of "subject-path" or "subject-digest".
+    required: false
+  subject-name:
+    description: >
+      Subject name as it should appear in the provenance statement. Required
+      unless "subject-path" is specified, in which case it will be inferred from
+      the path.
+  push-to-registry:
+    description: >
+      Whether to push the provenance statement to the image registry. Requires
+      that the "subject-name" parameter specify the fully-qualified image name
+      and that the "subject-digest" parameter be specified. Defaults to false.
+    default: false
+    required: false
 outputs:
-  time:
-    description: 'Your output description here'
+  bundle-path:
+    description: 'The path to the file containing the attestation bundle(s).'
+    value: ${{ steps.attest.outputs.bundle-path }}

 runs:
-  using: node20
-  main: dist/index.js
+  using: 'composite'
+  steps:
+    - uses: ./generate-build-provenance-statement
+      id: generate-build-provenance-statement
+      with:
+        github-token: ${{ inputs.github-token }}
+        subject-path: ${{ inputs.subject-path }}
+        subject-digest: ${{ inputs.subject-digest }}
+        subject-name: ${{ inputs.subject-name }}
+        push-to-registry: ${{ inputs.push-to-registry }}
+    - uses: actions/attest
+      id: attest
+      with:
+        github-token: ${{ inputs.github-token }}
+        subject-path: ${{ inputs.subject-path }}
+        subject-digest: ${{ inputs.subject-digest }}
+        subject-name: ${{ inputs.subject-name }}
+        push-to-registry: ${{ inputs.push-to-registry }}
+        predicate-type: ${{ steps.generate-build-provenance-statement.outputs.predicate-type }}
+        predicate: ${{ steps.generate-build-provenance-statement.outputs.predicate }}
--- a/badges/coverage.svg
+++ b/badges/coverage.svg
@ -1 +1 @@
-<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="106" height="20" role="img" aria-label="Coverage: 100%"><title>Coverage: 100%</title><linearGradient id="s" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="r"><rect width="106" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#r)"><rect width="63" height="20" fill="#555"/><rect x="63" width="43" height="20" fill="#4c1"/><rect width="106" height="20" fill="url(#s)"/></g><g fill="#fff" text-anchor="middle" font-family="Verdana,Geneva,DejaVu Sans,sans-serif" text-rendering="geometricPrecision" font-size="110"><text aria-hidden="true" x="325" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="530">Coverage</text><text x="325" y="140" transform="scale(.1)" fill="#fff" textLength="530">Coverage</text><text aria-hidden="true" x="835" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="330">100%</text><text x="835" y="140" transform="scale(.1)" fill="#fff" textLength="330">100%</text></g></svg>
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="92" height="20" role="img" aria-label="Coverage: 0%"><title>Coverage: 0%</title><linearGradient id="s" x2="0" y2="100%"><stop offset="0" stop-color="#bbb" stop-opacity=".1"/><stop offset="1" stop-opacity=".1"/></linearGradient><clipPath id="r"><rect width="92" height="20" rx="3" fill="#fff"/></clipPath><g clip-path="url(#r)"><rect width="63" height="20" fill="#555"/><rect x="63" width="29" height="20" fill="#e05d44"/><rect width="92" height="20" fill="url(#s)"/></g><g fill="#fff" text-anchor="middle" font-family="Verdana,Geneva,DejaVu Sans,sans-serif" text-rendering="geometricPrecision" font-size="110"><text aria-hidden="true" x="325" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="530">Coverage</text><text x="325" y="140" transform="scale(.1)" fill="#fff" textLength="530">Coverage</text><text aria-hidden="true" x="765" y="150" fill="#010101" fill-opacity=".3" transform="scale(.1)" textLength="190">0%</text><text x="765" y="140" transform="scale(.1)" fill="#fff" textLength="190">0%</text></g></svg>
--- a/dist/index.js
+++ b/dist/index.js
--- a/dist/licenses.txt
+++ b/dist/licenses.txt
--- a/generate-build-provenance-statement/action.yml
+++ b/generate-build-provenance-statement/action.yml
@ -0,0 +1,43 @@
+name: 'Generate Build Provenance Statement'
+description: 'Generate provenance statement for build artifacts'
+author: 'GitHub'
+
+inputs:
+  github-token:
+    description: >
+      The GitHub token used to make authenticated API requests.
+    default: ${{ github.token }}
+    required: false
+  subject-path:
+    description: >
+      Path to the artifact for which provenance will be generated. Must specify
+      exactly one of "subject-path" or "subject-digest".
+    required: false
+  subject-digest:
+    description: >
+      Digest of the subject for which provenance will be generated. Must be in
+      the form "algorithm:hex_digest" (e.g. "sha256:abc123..."). Must specify
+      exactly one of "subject-path" or "subject-digest".
+    required: false
+  subject-name:
+    description: >
+      Subject name as it should appear in the provenance statement. Required
+      unless "subject-path" is specified, in which case it will be inferred from
+      the path.
+  push-to-registry:
+    description: >
+      Whether to push the provenance statement to the image registry. Requires
+      that the "subject-name" parameter specify the fully-qualified image name
+      and that the "subject-digest" parameter be specified. Defaults to false.
+    default: false
+    required: false
+outputs:
+  predicate:
+    description: >
+      The JSON-serialized of the attestation predicate.
+  predicate-type:
+    description: >
+      URI identifying the type of the predicate.
+runs:
+  using: node20
+  main: ../dist/index.js
--- a/package-lock.json
+++ b/package-lock.json
--- a/package.json
+++ b/package.json
@ -25,6 +25,7 @@
  },
  "scripts": {
    "bundle": "npm run format:write && npm run package",
+    "prepackage": "npm run build --workspace packages/attest",
    "ci-test": "jest",
    "coverage": "make-coverage-badge --output-path ./badges/coverage.svg",
    "format:write": "prettier --write **/*.ts",
@ -85,5 +86,8 @@
    "prettier-eslint": "^16.3.0",
    "ts-jest": "^29.1.2",
    "typescript": "^5.3.3"
-  }
+  },
+  "workspaces": [
+    "./packages/*"
+  ]
 }
--- a/packages/attest/dist/attest.d.ts
+++ b/packages/attest/dist/attest.d.ts
@ -0,0 +1,16 @@
+import { SignOptions } from './sign';
+import type { Attestation } from './shared.types';
+type AttestBaseOptions = SignOptions & {
+    subjectName: string;
+    subjectDigest: Record<string, string>;
+    token: string;
+    skipWrite?: boolean;
+};
+export type AttestOptions = AttestBaseOptions & {
+    predicateType: string;
+    predicate: object;
+};
+export type AttestProvenanceOptions = AttestBaseOptions;
+export declare function attest(options: AttestOptions): Promise<Attestation>;
+export declare function attestProvenance(options: AttestProvenanceOptions): Promise<Attestation>;
+export {};
--- a/packages/attest/dist/attest.js
+++ b/packages/attest/dist/attest.js
@ -0,0 +1,62 @@
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.attestProvenance = exports.attest = void 0;
+const bundle_1 = require("@sigstore/bundle");
+const provenance_1 = require("./provenance");
+const sign_1 = require("./sign");
+const store_1 = require("./store");
+const assert_1 = __importDefault(require("assert"));
+const crypto_1 = require("crypto");
+const INTOTO_PAYLOAD_TYPE = 'application/vnd.in-toto+json';
+const INTOTO_STATEMENT_V1_TYPE = 'https://in-toto.io/Statement/v1';
+async function attest(options) {
+    const subject = {
+        name: options.subjectName,
+        digest: options.subjectDigest
+    };
+    const statement = {
+        _type: INTOTO_STATEMENT_V1_TYPE,
+        subject: [subject],
+        predicateType: options.predicateType,
+        predicate: options.predicate
+    };
+    // Sign the provenance statement
+    const payload = {
+        body: Buffer.from(JSON.stringify(statement)),
+        type: INTOTO_PAYLOAD_TYPE
+    };
+    const bundle = await (0, sign_1.signPayload)(payload, options);
+    // Store the attestation
+    let attestationID;
+    if (options.skipWrite !== true) {
+        attestationID = await (0, store_1.writeAttestation)((0, bundle_1.bundleToJSON)(bundle), options.token);
+    }
+    return toAttestation(bundle, attestationID);
+}
+exports.attest = attest;
+async function attestProvenance(options) {
+    const predicate = (0, provenance_1.generateProvenancePredicate)(process.env);
+    return attest({
+        ...options,
+        predicateType: predicate.type,
+        predicate: predicate.params
+    });
+}
+exports.attestProvenance = attestProvenance;
+function toAttestation(bundle, attestationID) {
+    // Extract the signing certificate from the bundle
+    (0, assert_1.default)(bundle.verificationMaterial.content.$case === 'x509CertificateChain', 'Bundle must contain an x509 certificate chain');
+    const signingCert = new crypto_1.X509Certificate(bundle.verificationMaterial.content.x509CertificateChain.certificates[0].rawBytes);
+    // Determine if we can provide a link to the transparency log
+    const tlogEntries = bundle.verificationMaterial.tlogEntries;
+    const tlogID = tlogEntries.length > 0 ? tlogEntries[0].logIndex : undefined;
+    return {
+        bundle: (0, bundle_1.bundleToJSON)(bundle),
+        certificate: signingCert.toString(),
+        tlogID,
+        attestationID
+    };
+}
--- a/packages/attest/dist/index.d.ts
+++ b/packages/attest/dist/index.d.ts
@ -0,0 +1,4 @@
+export { AttestOptions, AttestProvenanceOptions, attest, attestProvenance } from './attest';
+export { generateProvenancePredicate } from './provenance';
+export { generateSBOMPredicate } from './sbom';
+export type { Attestation, Predicate, Subject, SBOM } from './shared.types';
--- a/packages/attest/dist/index.js
+++ b/packages/attest/dist/index.js
@ -0,0 +1,10 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.generateSBOMPredicate = exports.generateProvenancePredicate = exports.attestProvenance = exports.attest = void 0;
+var attest_1 = require("./attest");
+Object.defineProperty(exports, "attest", { enumerable: true, get: function () { return attest_1.attest; } });
+Object.defineProperty(exports, "attestProvenance", { enumerable: true, get: function () { return attest_1.attestProvenance; } });
+var provenance_1 = require("./provenance");
+Object.defineProperty(exports, "generateProvenancePredicate", { enumerable: true, get: function () { return provenance_1.generateProvenancePredicate; } });
+var sbom_1 = require("./sbom");
+Object.defineProperty(exports, "generateSBOMPredicate", { enumerable: true, get: function () { return sbom_1.generateSBOMPredicate; } });
--- a/packages/attest/dist/provenance.d.ts
+++ b/packages/attest/dist/provenance.d.ts
@ -0,0 +1,9 @@
+/// <reference types="node" />
+/// <reference types="node" />
+/// <reference types="node" />
+/// <reference types="node" />
+/// <reference types="node" />
+import type { Predicate, Subject } from './shared.types';
+export declare const SLSA_PREDICATE_V1_TYPE = "https://slsa.dev/provenance/v1";
+export declare const generateProvenancePredicate: (env: NodeJS.ProcessEnv) => Predicate;
+export declare const generateProvenance: (subject: Subject, env: NodeJS.ProcessEnv) => object;
--- a/packages/attest/dist/provenance.js
+++ b/packages/attest/dist/provenance.js
@ -0,0 +1,65 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.generateProvenance = exports.generateProvenancePredicate = exports.SLSA_PREDICATE_V1_TYPE = void 0;
+const INTOTO_STATEMENT_V1_TYPE = 'https://in-toto.io/Statement/v1';
+exports.SLSA_PREDICATE_V1_TYPE = 'https://slsa.dev/provenance/v1';
+const GITHUB_BUILDER_ID_PREFIX = 'https://github.com/actions/runner';
+const GITHUB_BUILD_TYPE = 'https://slsa-framework.github.io/github-actions-buildtypes/workflow/v1';
+const generateProvenancePredicate = (env) => {
+    const workflow = env.GITHUB_WORKFLOW_REF || /* istanbul ignore next */ '';
+    // Split just the path and ref from the workflow string.
+    // owner/repo/.github/workflows/main.yml@main =>
+    //   .github/workflows/main.yml, main
+    const [workflowPath, workflowRef] = workflow
+        .replace(`${env.GITHUB_REPOSITORY}/`, '')
+        .split('@');
+    return {
+        type: exports.SLSA_PREDICATE_V1_TYPE,
+        params: {
+            buildDefinition: {
+                buildType: GITHUB_BUILD_TYPE,
+                externalParameters: {
+                    workflow: {
+                        ref: workflowRef,
+                        repository: `${env.GITHUB_SERVER_URL}/${env.GITHUB_REPOSITORY}`,
+                        path: workflowPath
+                    }
+                },
+                internalParameters: {
+                    github: {
+                        event_name: env.GITHUB_EVENT_NAME,
+                        repository_id: env.GITHUB_REPOSITORY_ID,
+                        repository_owner_id: env.GITHUB_REPOSITORY_OWNER_ID
+                    }
+                },
+                resolvedDependencies: [
+                    {
+                        uri: `git+${env.GITHUB_SERVER_URL}/${env.GITHUB_REPOSITORY}@${env.GITHUB_REF}`,
+                        digest: {
+                            gitCommit: env.GITHUB_SHA
+                        }
+                    }
+                ]
+            },
+            runDetails: {
+                builder: {
+                    id: `${GITHUB_BUILDER_ID_PREFIX}/${env.RUNNER_ENVIRONMENT}`
+                },
+                metadata: {
+                    invocationId: `${env.GITHUB_SERVER_URL}/${env.GITHUB_REPOSITORY}/actions/runs/${env.GITHUB_RUN_ID}/attempts/${env.GITHUB_RUN_ATTEMPT}`
+                }
+            }
+        }
+    };
+};
+exports.generateProvenancePredicate = generateProvenancePredicate;
+const generateProvenance = (subject, env) => {
+    const predicate = (0, exports.generateProvenancePredicate)(env);
+    return {
+        _type: INTOTO_STATEMENT_V1_TYPE,
+        subject: [subject],
+        predicateType: predicate.type,
+        predicate: predicate.params
+    };
+};
+exports.generateProvenance = generateProvenance;
--- a/packages/attest/dist/sbom.d.ts
+++ b/packages/attest/dist/sbom.d.ts
@ -0,0 +1,2 @@
+import type { SBOM, Predicate } from './shared.types';
+export declare const generateSBOMPredicate: (sbom: SBOM) => Predicate;
--- a/packages/attest/dist/sbom.js
+++ b/packages/attest/dist/sbom.js
@ -0,0 +1,32 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.generateSBOMPredicate = void 0;
+const generateSBOMPredicate = (sbom) => {
+    if (sbom.type === 'spdx') {
+        return generateSPDXIntoto(sbom.object);
+    }
+    if (sbom.type === 'cyclonedx') {
+        return generateCycloneDXIntoto(sbom.object);
+    }
+    throw new Error('Unsupported SBOM format');
+};
+exports.generateSBOMPredicate = generateSBOMPredicate;
+// ref: https://github.com/in-toto/attestation/blob/main/spec/predicates/spdx.md
+const generateSPDXIntoto = (sbom) => {
+    const spdxVersion = sbom?.['spdxVersion'];
+    if (!spdxVersion) {
+        throw new Error('Cannot find spdxVersion in the SBOM');
+    }
+    const version = spdxVersion.split('-')[1];
+    return {
+        type: `https://spdx.dev/Document/v${version}`,
+        params: sbom
+    };
+};
+// ref: https://github.com/in-toto/attestation/blob/main/spec/predicates/cyclonedx.md
+const generateCycloneDXIntoto = (sbom) => {
+    return {
+        type: 'https://cyclonedx.org/bom',
+        params: sbom
+    };
+};
--- a/packages/attest/dist/shared.types.d.ts
+++ b/packages/attest/dist/shared.types.d.ts
@ -0,0 +1,19 @@
+import type { SerializedBundle } from '@sigstore/bundle';
+export type Subject = {
+    name: string;
+    digest: Record<string, string>;
+};
+export type Predicate = {
+    type: string;
+    params: object;
+};
+export type Attestation = {
+    bundle: SerializedBundle;
+    certificate: string;
+    tlogID?: string;
+    attestationID?: string;
+};
+export type SBOM = {
+    type: 'spdx' | 'cyclonedx';
+    object: object;
+};
--- a/packages/attest/dist/shared.types.js
+++ b/packages/attest/dist/shared.types.js
@ -0,0 +1,2 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
--- a/packages/attest/dist/sign.d.ts
+++ b/packages/attest/dist/sign.d.ts
@ -0,0 +1,16 @@
+/// <reference types="node" />
+import { Bundle } from '@sigstore/bundle';
+import { IdentityProvider } from '@sigstore/sign';
+export type Payload = {
+    body: Buffer;
+    type: string;
+};
+export type SignOptions = {
+    fulcioURL: string;
+    rekorURL?: string;
+    tsaServerURL?: string;
+    identityProvider?: IdentityProvider;
+    timeout?: number;
+    retry?: number;
+};
+export declare const signPayload: (payload: Payload, options: SignOptions) => Promise<Bundle>;
--- a/packages/attest/dist/sign.js
+++ b/packages/attest/dist/sign.js
@ -0,0 +1,46 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.signPayload = void 0;
+const sign_1 = require("@sigstore/sign");
+const OIDC_AUDIENCE = 'sigstore';
+const DEFAULT_TIMEOUT = 10000;
+const DEFAULT_RETRIES = 3;
+// Signs the provided payload with Sigstore.
+const signPayload = async (payload, options) => {
+    const artifact = {
+        data: payload.body,
+        type: payload.type
+    };
+    // Sign the artifact and build the bundle
+    return initBundleBuilder(options).create(artifact);
+};
+exports.signPayload = signPayload;
+// Assembles the Sigstore bundle builder with the appropriate options
+const initBundleBuilder = (opts) => {
+    const identityProvider = opts.identityProvider || new sign_1.CIContextProvider(OIDC_AUDIENCE);
+    const timeout = opts.timeout || DEFAULT_TIMEOUT;
+    const retry = opts.retry || DEFAULT_RETRIES;
+    const witnesses = [];
+    const signer = new sign_1.FulcioSigner({
+        identityProvider: identityProvider,
+        fulcioBaseURL: opts.fulcioURL,
+        timeout: timeout,
+        retry: retry
+    });
+    if (opts.rekorURL) {
+        witnesses.push(new sign_1.RekorWitness({
+            rekorBaseURL: opts.rekorURL,
+            entryType: 'dsse',
+            timeout: timeout,
+            retry: retry
+        }));
+    }
+    if (opts.tsaServerURL) {
+        witnesses.push(new sign_1.TSAWitness({
+            tsaBaseURL: opts.tsaServerURL,
+            timeout: timeout,
+            retry: retry
+        }));
+    }
+    return new sign_1.DSSEBundleBuilder({ signer, witnesses });
+};
--- a/packages/attest/dist/store.d.ts
+++ b/packages/attest/dist/store.d.ts
@ -0,0 +1 @@
+export declare const writeAttestation: (attestation: unknown, token: string) => Promise<string>;
--- a/packages/attest/dist/store.js
+++ b/packages/attest/dist/store.js
@ -0,0 +1,51 @@
+"use strict";
+var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
+    if (k2 === undefined) k2 = k;
+    var desc = Object.getOwnPropertyDescriptor(m, k);
+    if (!desc || ("get" in desc ? !m.__esModule : desc.writable || desc.configurable)) {
+      desc = { enumerable: true, get: function() { return m[k]; } };
+    }
+    Object.defineProperty(o, k2, desc);
+}) : (function(o, m, k, k2) {
+    if (k2 === undefined) k2 = k;
+    o[k2] = m[k];
+}));
+var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
+    Object.defineProperty(o, "default", { enumerable: true, value: v });
+}) : function(o, v) {
+    o["default"] = v;
+});
+var __importStar = (this && this.__importStar) || function (mod) {
+    if (mod && mod.__esModule) return mod;
+    var result = {};
+    if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
+    __setModuleDefault(result, mod);
+    return result;
+};
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.writeAttestation = void 0;
+const github = __importStar(require("@actions/github"));
+const make_fetch_happen_1 = __importDefault(require("make-fetch-happen"));
+const CREATE_ATTESTATION_REQUEST = 'POST /repos/{owner}/{repo}/attestations';
+// Upload the attestation to the repository's attestations endpoint. Returns the
+// ID of the uploaded attestation.
+const writeAttestation = async (attestation, token) => {
+    const octokit = github.getOctokit(token, { request: { fetch: make_fetch_happen_1.default } });
+    try {
+        const response = await octokit.request(CREATE_ATTESTATION_REQUEST, {
+            owner: github.context.repo.owner,
+            repo: github.context.repo.repo,
+            data: { bundle: attestation }
+        });
+        return response.data?.id;
+    }
+    catch (err) {
+        /* istanbul ignore next */
+        const message = err instanceof Error ? err.message : err;
+        throw new Error(`Failed to persist attestation: ${message}`);
+    }
+};
+exports.writeAttestation = writeAttestation;
--- a/packages/attest/jest.config.js
+++ b/packages/attest/jest.config.js
@ -0,0 +1,5 @@
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  testMatch: ['**/__tests__/*.test.ts'],
+};
--- a/packages/attest/package.json
+++ b/packages/attest/package.json
@ -0,0 +1,44 @@
+{
+  "name": "@actions/attest",
+  "version": "0.0.0",
+  "description": "Base library for Sigstore",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "scripts": {
+    "clean": "shx rm -rf dist *.tsbuildinfo",
+    "build": "tsc --build",
+    "test": "jest"
+  },
+  "files": [
+    "dist"
+  ],
+  "author": "bdehamer@github.com",
+  "license": "Apache-2.0",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/github/attest-js.git"
+  },
+  "bugs": {
+    "url": "https://github.com/github/attest-js/issues"
+  },
+  "homepage": "https://github.com/github/attest-js/tree/main/packages/core#readme",
+  "publishConfig": {
+    "provenance": true
+  },
+  "devDependencies": {
+    "@sigstore/mock": "^0.6.4",
+    "@total-typescript/shoehorn": "^0.1.1",
+    "@tsconfig/node18": "^18.2.2",
+    "@types/make-fetch-happen": "^10.0.4",
+    "nock": "^13.5.1"
+  },
+  "dependencies": {
+    "@actions/github": "^6.0.0",
+    "@sigstore/bundle": "^2.2.0",
+    "@sigstore/sign": "^2.2.3",
+    "make-fetch-happen": "^13.0.0"
+  },
+  "engines": {
+    "node": "^18.17.0 || >=20.5.0"
+  }
+}
--- a/packages/attest/src/tests/snapshots/provenance.test.ts.snap
+++ b/packages/attest/src/tests/snapshots/provenance.test.ts.snap
@ -0,0 +1,51 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`generateProvenance returns a provenance hydrated from env vars 1`] = `
+{
+  "_type": "https://in-toto.io/Statement/v1",
+  "predicate": {
+    "buildDefinition": {
+      "buildType": "https://slsa-framework.github.io/github-actions-buildtypes/workflow/v1",
+      "externalParameters": {
+        "workflow": {
+          "path": ".github/workflows/main.yml",
+          "ref": "main",
+          "repository": "https://github.com/owner/repo",
+        },
+      },
+      "internalParameters": {
+        "github": {
+          "event_name": "push",
+          "repository_id": "repo-id",
+          "repository_owner_id": "owner-id",
+        },
+      },
+      "resolvedDependencies": [
+        {
+          "digest": {
+            "gitCommit": "babca52ab0c93ae16539e5923cb0d7403b9a093b",
+          },
+          "uri": "git+https://github.com/owner/repo@refs/heads/main",
+        },
+      ],
+    },
+    "runDetails": {
+      "builder": {
+        "id": "https://github.com/actions/runner/github-hosted",
+      },
+      "metadata": {
+        "invocationId": "https://github.com/owner/repo/actions/runs/run-id/attempts/run-attempt",
+      },
+    },
+  },
+  "predicateType": "https://slsa.dev/provenance/v1",
+  "subject": [
+    {
+      "digest": {
+        "sha256": "7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32",
+      },
+      "name": "subjecty",
+    },
+  ],
+}
+`;
--- a/packages/attest/src/tests/attest.test.ts
+++ b/packages/attest/src/tests/attest.test.ts
@ -0,0 +1,154 @@
+import { mockFulcio, mockRekor, mockTSA } from '@sigstore/mock'
+import nock from 'nock'
+import { attestProvenance } from '../attest'
+
+describe('attest functions', () => {
+  // Capture original environment variables and GitHub context so we can restore
+  // them after each test
+  const originalEnv = process.env
+
+  // Fake an OIDC token
+  const subject = 'foo@bar.com'
+  const oidcPayload = { sub: subject, iss: '' }
+  const oidcToken = `.${Buffer.from(JSON.stringify(oidcPayload)).toString(
+    'base64'
+  )}.}`
+
+  const tokenURL = 'https://token.url'
+  const fulcioURL = 'https://fulcio.url'
+  const rekorURL = 'https://rekor.url'
+  const tsaServerURL = 'https://tsa.url'
+  const attestationID = '1234567890'
+
+  beforeEach(async () => {
+    jest.clearAllMocks()
+
+    nock(tokenURL)
+      .get('/')
+      .query({ audience: 'sigstore' })
+      .reply(200, { value: oidcToken })
+
+    // Mock Fulcio endpoint
+    await mockFulcio({ baseURL: fulcioURL, strict: false })
+
+    // Set-up GHA environment variables
+    process.env = {
+      ...originalEnv,
+      ACTIONS_ID_TOKEN_REQUEST_URL: tokenURL,
+      ACTIONS_ID_TOKEN_REQUEST_TOKEN: 'token'
+    }
+  })
+
+  afterEach(() => {
+    // Restore the original environment
+    process.env = originalEnv
+  })
+
+  describe('#attestProvenance', () => {
+    const env = {
+      GITHUB_REPOSITORY: 'owner/repo',
+      GITHUB_REF: 'refs/heads/main',
+      GITHUB_SHA: 'babca52ab0c93ae16539e5923cb0d7403b9a093b',
+      GITHUB_WORKFLOW_REF: 'owner/repo/.github/workflows/main.yml@main',
+      GITHUB_SERVER_URL: 'https://github.com',
+      GITHUB_EVENT_NAME: 'push',
+      GITHUB_REPOSITORY_ID: 'repo-id',
+      GITHUB_REPOSITORY_OWNER_ID: 'owner-id',
+      GITHUB_RUN_ID: 'run-id',
+      GITHUB_RUN_ATTEMPT: 'run-attempt',
+      RUNNER_ENVIRONMENT: 'github-hosted'
+    }
+
+    beforeEach(() => {
+      process.env = { ...process.env, ...env }
+    })
+
+    describe('when the timestamp authority URL is set', () => {
+      beforeEach(async () => {
+        await mockTSA({ baseURL: tsaServerURL })
+
+        // Mock GH attestations API
+        nock('https://api.github.com')
+          .post(/^\/repos\/.*\/.*\/attestations$/)
+          .reply(201, { id: attestationID })
+      })
+
+      it('attests provenance', async () => {
+        const attestation = await attestProvenance({
+          subjectName: 'subjective',
+          subjectDigest: {
+            sha256:
+              '7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32'
+          },
+          token: 'token',
+          fulcioURL,
+          tsaServerURL
+        })
+
+        expect(attestation).toBeDefined()
+        expect(attestation.bundle).toBeDefined()
+        expect(attestation.certificate).toMatch(/-----BEGIN CERTIFICATE-----/)
+        expect(attestation.tlogID).toBeUndefined()
+        expect(attestation.attestationID).toBe(attestationID)
+      })
+    })
+
+    describe('when the transparency log URL is set', () => {
+      beforeEach(async () => {
+        await mockRekor({ baseURL: rekorURL })
+
+        // Mock GH attestations API
+        nock('https://api.github.com')
+          .post(/^\/repos\/.*\/.*\/attestations$/)
+          .reply(201, { id: attestationID })
+      })
+
+      it('attests provenance', async () => {
+        const attestation = await attestProvenance({
+          subjectName: 'subjective',
+          subjectDigest: {
+            sha256:
+              '7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32'
+          },
+          token: 'token',
+          fulcioURL,
+          rekorURL
+        })
+
+        expect(attestation).toBeDefined()
+        expect(attestation.bundle).toBeDefined()
+        expect(attestation.certificate).toMatch(/-----BEGIN CERTIFICATE-----/)
+        expect(attestation.tlogID).toBeDefined()
+        expect(attestation.attestationID).toBe(attestationID)
+      })
+    })
+
+    describe('when skipWrite is set to true', () => {
+      beforeEach(async () => {
+        await mockRekor({ baseURL: rekorURL })
+        await mockTSA({ baseURL: tsaServerURL })
+      })
+
+      it('attests provenance', async () => {
+        const attestation = await attestProvenance({
+          subjectName: 'subjective',
+          subjectDigest: {
+            sha256:
+              '7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32'
+          },
+          token: 'token',
+          fulcioURL,
+          rekorURL,
+          tsaServerURL,
+          skipWrite: true
+        })
+
+        expect(attestation).toBeDefined()
+        expect(attestation.bundle).toBeDefined()
+        expect(attestation.certificate).toMatch(/-----BEGIN CERTIFICATE-----/)
+        expect(attestation.tlogID).toBeDefined()
+        expect(attestation.attestationID).toBeUndefined()
+      })
+    })
+  })
+})
--- a/packages/attest/src/tests/index.test.ts
+++ b/packages/attest/src/tests/index.test.ts
@ -0,0 +1,32 @@
+import { fromPartial } from '@total-typescript/shoehorn'
+import {
+  AttestOptions,
+  AttestProvenanceOptions,
+  Attestation,
+  Predicate,
+  Subject,
+  attest,
+  attestProvenance
+} from '..'
+
+it('exports functions', () => {
+  expect(attestProvenance).toBeInstanceOf(Function)
+  expect(attest).toBeInstanceOf(Function)
+})
+
+it('exports types', async () => {
+  const attestation: Attestation = fromPartial({})
+  expect(attestation).toBeDefined()
+
+  const attestOptions: AttestOptions = fromPartial({})
+  expect(attestOptions).toBeDefined()
+
+  const attestProvenanceOptions: AttestProvenanceOptions = fromPartial({})
+  expect(attestProvenanceOptions).toBeDefined()
+
+  const subject: Subject = fromPartial({})
+  expect(subject).toBeDefined()
+
+  const predicate: Predicate = fromPartial({})
+  expect(predicate).toBeDefined()
+})
--- a/packages/attest/src/tests/provenance.test.ts
+++ b/packages/attest/src/tests/provenance.test.ts
@ -0,0 +1,30 @@
+import { generateProvenance } from '../provenance'
+import type { Subject } from '../shared.types'
+
+describe('generateProvenance', () => {
+  const subject: Subject = {
+    name: 'subjecty',
+    digest: {
+      sha256: '7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32'
+    }
+  }
+
+  const env = {
+    GITHUB_REPOSITORY: 'owner/repo',
+    GITHUB_REF: 'refs/heads/main',
+    GITHUB_SHA: 'babca52ab0c93ae16539e5923cb0d7403b9a093b',
+    GITHUB_WORKFLOW_REF: 'owner/repo/.github/workflows/main.yml@main',
+    GITHUB_SERVER_URL: 'https://github.com',
+    GITHUB_EVENT_NAME: 'push',
+    GITHUB_REPOSITORY_ID: 'repo-id',
+    GITHUB_REPOSITORY_OWNER_ID: 'owner-id',
+    GITHUB_RUN_ID: 'run-id',
+    GITHUB_RUN_ATTEMPT: 'run-attempt',
+    RUNNER_ENVIRONMENT: 'github-hosted'
+  }
+
+  it('returns a provenance hydrated from env vars', () => {
+    const provenance = generateProvenance(subject, env)
+    expect(provenance).toMatchSnapshot()
+  })
+})
--- a/packages/attest/src/tests/sign.test.ts
+++ b/packages/attest/src/tests/sign.test.ts
@ -0,0 +1,105 @@
+import { mockFulcio, mockRekor, mockTSA } from '@sigstore/mock'
+import nock from 'nock'
+import { Payload, signPayload } from '../sign'
+
+describe('signProvenance', () => {
+  const originalEnv = process.env
+
+  // Fake an OIDC token
+  const subject = 'foo@bar.com'
+  const oidcPayload = { sub: subject, iss: '' }
+  const oidcToken = `.${Buffer.from(JSON.stringify(oidcPayload)).toString(
+    'base64'
+  )}.}`
+
+  // Dummy provenance to be signed
+  const provenance = {
+    _type: 'https://in-toto.io/Statement/v1',
+    subject: {
+      name: 'subjective',
+      digest: {
+        sha256:
+          '7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32'
+      }
+    }
+  }
+
+  const payload: Payload = {
+    body: Buffer.from(JSON.stringify(provenance)),
+    type: 'application/vnd.in-toto+json'
+  }
+
+  const fulcioURL = 'https://fulcio.url'
+  const rekorURL = 'https://rekor.url'
+  const tsaServerURL = 'https://tsa.url'
+
+  beforeEach(() => {
+    // Mock OIDC token endpoint
+    const tokenURL = 'https://token.url'
+
+    process.env = {
+      ...originalEnv,
+      ACTIONS_ID_TOKEN_REQUEST_URL: tokenURL,
+      ACTIONS_ID_TOKEN_REQUEST_TOKEN: 'token'
+    }
+
+    nock(tokenURL)
+      .get('/')
+      .query({ audience: 'sigstore' })
+      .reply(200, { value: oidcToken })
+  })
+
+  afterEach(() => {
+    process.env = originalEnv
+  })
+
+  describe('when visibility is public', () => {
+    beforeEach(async () => {
+      await mockFulcio({ baseURL: fulcioURL, strict: false })
+      await mockRekor({ baseURL: rekorURL })
+    })
+
+    it('returns a bundle', async () => {
+      const att = await signPayload(payload, { fulcioURL, rekorURL })
+
+      expect(att).toBeDefined()
+      expect(att.mediaType).toEqual(
+        'application/vnd.dev.sigstore.bundle+json;version=0.2'
+      )
+
+      expect(att.content.$case).toEqual('dsseEnvelope')
+      expect(att.verificationMaterial.content.$case).toEqual(
+        'x509CertificateChain'
+      )
+      expect(att.verificationMaterial.tlogEntries).toHaveLength(1)
+      expect(
+        att.verificationMaterial.timestampVerificationData?.rfc3161Timestamps
+      ).toHaveLength(0)
+    })
+  })
+
+  describe('when visibility is private', () => {
+    beforeEach(async () => {
+      await mockFulcio({ baseURL: fulcioURL, strict: false })
+      await mockTSA({ baseURL: tsaServerURL })
+    })
+
+    it('returns a bundle', async () => {
+      const att = await signPayload(payload, { fulcioURL, tsaServerURL })
+
+      expect(att).toBeDefined()
+      expect(att.mediaType).toEqual(
+        'application/vnd.dev.sigstore.bundle+json;version=0.2'
+      )
+
+      expect(att.content.$case).toEqual('dsseEnvelope')
+      expect(att.verificationMaterial.content.$case).toEqual(
+        'x509CertificateChain'
+      )
+      expect(att.verificationMaterial.tlogEntries).toHaveLength(0)
+      expect(
+        att.verificationMaterial.timestampVerificationData?.rfc3161Timestamps
+      ).toHaveLength(1)
+    })
+  })
+})
--- a/packages/attest/src/tests/store.test.ts
+++ b/packages/attest/src/tests/store.test.ts
@ -0,0 +1,45 @@
+import nock from 'nock'
+import { writeAttestation } from '../store'
+
+describe('writeAttestation', () => {
+  const originalEnv = process.env
+  const attestation = { foo: 'bar ' }
+  const token = 'token'
+
+  beforeEach(() => {
+    process.env = {
+      ...originalEnv,
+      GITHUB_REPOSITORY: 'foo/bar'
+    }
+  })
+
+  afterEach(() => {
+    process.env = originalEnv
+  })
+
+  describe('when the api call is successful', () => {
+    beforeEach(() => {
+      nock('https://api.github.com')
+        .matchHeader('authorization', `token ${token}`)
+        .post('/repos/foo/bar/attestations', { bundle: attestation })
+        .reply(201, { id: '123' })
+    })
+
+    it('persists the attestation', async () => {
+      await expect(writeAttestation(attestation, token)).resolves.toEqual('123')
+    })
+  })
+
+  describe('when the api call fails', () => {
+    beforeEach(() => {
+      nock('https://api.github.com')
+        .matchHeader('authorization', `token ${token}`)
+        .post('/repos/foo/bar/attestations', { bundle: attestation })
+        .reply(500, 'oops')
+    })
+
+    it('persists the attestation', async () => {
+      await expect(writeAttestation(attestation, token)).rejects.toThrow(/oops/)
+    })
+  })
+})
--- a/packages/attest/src/attest.ts
+++ b/packages/attest/src/attest.ts
@ -0,0 +1,88 @@
+import { Bundle, bundleToJSON } from '@sigstore/bundle'
+import { generateProvenancePredicate } from './provenance'
+import { Payload, SignOptions, signPayload } from './sign'
+import { writeAttestation } from './store'
+
+import assert from 'assert'
+import { X509Certificate } from 'crypto'
+import type { Attestation, Subject } from './shared.types'
+
+const INTOTO_PAYLOAD_TYPE = 'application/vnd.in-toto+json'
+const INTOTO_STATEMENT_V1_TYPE = 'https://in-toto.io/Statement/v1'
+
+type AttestBaseOptions = SignOptions & {
+  subjectName: string
+  subjectDigest: Record<string, string>
+  token: string
+  skipWrite?: boolean
+}
+
+export type AttestOptions = AttestBaseOptions & {
+  predicateType: string
+  predicate: object
+}
+
+export type AttestProvenanceOptions = AttestBaseOptions
+
+export async function attest(options: AttestOptions): Promise<Attestation> {
+  const subject: Subject = {
+    name: options.subjectName,
+    digest: options.subjectDigest
+  }
+
+  const statement = {
+    _type: INTOTO_STATEMENT_V1_TYPE,
+    subject: [subject],
+    predicateType: options.predicateType,
+    predicate: options.predicate
+  }
+
+  // Sign the provenance statement
+  const payload: Payload = {
+    body: Buffer.from(JSON.stringify(statement)),
+    type: INTOTO_PAYLOAD_TYPE
+  }
+  const bundle = await signPayload(payload, options)
+
+  // Store the attestation
+  let attestationID: string | undefined
+  if (options.skipWrite !== true) {
+    attestationID = await writeAttestation(bundleToJSON(bundle), options.token)
+  }
+
+  return toAttestation(bundle, attestationID)
+}
+
+export async function attestProvenance(
+  options: AttestProvenanceOptions
+): Promise<Attestation> {
+  const predicate = generateProvenancePredicate(process.env)
+  return attest({
+    ...options,
+    predicateType: predicate.type,
+    predicate: predicate.params
+  })
+}
+
+function toAttestation(bundle: Bundle, attestationID?: string): Attestation {
+  // Extract the signing certificate from the bundle
+  assert(
+    bundle.verificationMaterial.content.$case === 'x509CertificateChain',
+    'Bundle must contain an x509 certificate chain'
+  )
+
+  const signingCert = new X509Certificate(
+    bundle.verificationMaterial.content.x509CertificateChain.certificates[0].rawBytes
+  )
+
+  // Determine if we can provide a link to the transparency log
+  const tlogEntries = bundle.verificationMaterial.tlogEntries
+  const tlogID = tlogEntries.length > 0 ? tlogEntries[0].logIndex : undefined
+
+  return {
+    bundle: bundleToJSON(bundle),
+    certificate: signingCert.toString(),
+    tlogID,
+    attestationID
+  }
+}
--- a/packages/attest/src/index.ts
+++ b/packages/attest/src/index.ts
@ -0,0 +1,10 @@
+export {
+  AttestOptions,
+  AttestProvenanceOptions,
+  attest,
+  attestProvenance
+} from './attest'
+export { generateProvenancePredicate } from './provenance'
+export { generateSBOMPredicate } from './sbom'
+
+export type { Attestation, Predicate, Subject, SBOM } from './shared.types'
--- a/packages/attest/src/provenance.ts
+++ b/packages/attest/src/provenance.ts
@ -0,0 +1,72 @@
+import type { Predicate, Subject } from './shared.types'
+
+const INTOTO_STATEMENT_V1_TYPE = 'https://in-toto.io/Statement/v1'
+export const SLSA_PREDICATE_V1_TYPE = 'https://slsa.dev/provenance/v1'
+
+const GITHUB_BUILDER_ID_PREFIX = 'https://github.com/actions/runner'
+const GITHUB_BUILD_TYPE =
+  'https://slsa-framework.github.io/github-actions-buildtypes/workflow/v1'
+
+export const generateProvenancePredicate = (
+  env: NodeJS.ProcessEnv
+): Predicate => {
+  const workflow = env.GITHUB_WORKFLOW_REF || /* istanbul ignore next */ ''
+  // Split just the path and ref from the workflow string.
+  // owner/repo/.github/workflows/main.yml@main =>
+  //   .github/workflows/main.yml, main
+  const [workflowPath, workflowRef] = workflow
+    .replace(`${env.GITHUB_REPOSITORY}/`, '')
+    .split('@')
+
+  return {
+    type: SLSA_PREDICATE_V1_TYPE,
+    params: {
+      buildDefinition: {
+        buildType: GITHUB_BUILD_TYPE,
+        externalParameters: {
+          workflow: {
+            ref: workflowRef,
+            repository: `${env.GITHUB_SERVER_URL}/${env.GITHUB_REPOSITORY}`,
+            path: workflowPath
+          }
+        },
+        internalParameters: {
+          github: {
+            event_name: env.GITHUB_EVENT_NAME,
+            repository_id: env.GITHUB_REPOSITORY_ID,
+            repository_owner_id: env.GITHUB_REPOSITORY_OWNER_ID
+          }
+        },
+        resolvedDependencies: [
+          {
+            uri: `git+${env.GITHUB_SERVER_URL}/${env.GITHUB_REPOSITORY}@${env.GITHUB_REF}`,
+            digest: {
+              gitCommit: env.GITHUB_SHA
+            }
+          }
+        ]
+      },
+      runDetails: {
+        builder: {
+          id: `${GITHUB_BUILDER_ID_PREFIX}/${env.RUNNER_ENVIRONMENT}`
+        },
+        metadata: {
+          invocationId: `${env.GITHUB_SERVER_URL}/${env.GITHUB_REPOSITORY}/actions/runs/${env.GITHUB_RUN_ID}/attempts/${env.GITHUB_RUN_ATTEMPT}`
+        }
+      }
+    }
+  }
+}
+
+export const generateProvenance = (
+  subject: Subject,
+  env: NodeJS.ProcessEnv
+): object => {
+  const predicate = generateProvenancePredicate(env)
+  return {
+    _type: INTOTO_STATEMENT_V1_TYPE,
+    subject: [subject],
+    predicateType: predicate.type,
+    predicate: predicate.params
+  }
+}
--- a/packages/attest/src/sbom.ts
+++ b/packages/attest/src/sbom.ts
@ -0,0 +1,34 @@
+import type { SBOM, Predicate } from './shared.types'
+
+export const generateSBOMPredicate = (sbom: SBOM): Predicate => {
+  if (sbom.type === 'spdx') {
+    return generateSPDXIntoto(sbom.object)
+  }
+  if (sbom.type === 'cyclonedx') {
+    return generateCycloneDXIntoto(sbom.object)
+  }
+  throw new Error('Unsupported SBOM format')
+}
+
+// ref: https://github.com/in-toto/attestation/blob/main/spec/predicates/spdx.md
+const generateSPDXIntoto = (sbom: object): Predicate => {
+  const spdxVersion = (sbom as { spdxVersion?: string })?.['spdxVersion']
+  if (!spdxVersion) {
+    throw new Error('Cannot find spdxVersion in the SBOM')
+  }
+
+  const version = spdxVersion.split('-')[1]
+
+  return {
+    type: `https://spdx.dev/Document/v${version}`,
+    params: sbom
+  }
+}
+
+// ref: https://github.com/in-toto/attestation/blob/main/spec/predicates/cyclonedx.md
+const generateCycloneDXIntoto = (sbom: object): Predicate => {
+  return {
+    type: 'https://cyclonedx.org/bom',
+    params: sbom
+  }
+}
--- a/packages/attest/src/shared.types.ts
+++ b/packages/attest/src/shared.types.ts
@ -0,0 +1,22 @@
+import type { SerializedBundle } from '@sigstore/bundle'
+export type Subject = {
+  name: string
+  digest: Record<string, string>
+}
+
+export type Predicate = {
+  type: string
+  params: object
+}
+
+export type Attestation = {
+  bundle: SerializedBundle
+  certificate: string
+  tlogID?: string
+  attestationID?: string
+}
+
+export type SBOM = {
+  type: 'spdx' | 'cyclonedx'
+  object: object
+}
--- a/packages/attest/src/sign.ts
+++ b/packages/attest/src/sign.ts
@ -0,0 +1,82 @@
+import { Bundle } from '@sigstore/bundle'
+import {
+  BundleBuilder,
+  CIContextProvider,
+  DSSEBundleBuilder,
+  FulcioSigner,
+  IdentityProvider,
+  RekorWitness,
+  TSAWitness,
+  Witness
+} from '@sigstore/sign'
+
+const OIDC_AUDIENCE = 'sigstore'
+const DEFAULT_TIMEOUT = 10000
+const DEFAULT_RETRIES = 3
+
+export type Payload = {
+  body: Buffer
+  type: string
+}
+
+export type SignOptions = {
+  fulcioURL: string
+  rekorURL?: string
+  tsaServerURL?: string
+  identityProvider?: IdentityProvider
+  timeout?: number
+  retry?: number
+}
+
+// Signs the provided payload with Sigstore.
+export const signPayload = async (
+  payload: Payload,
+  options: SignOptions
+): Promise<Bundle> => {
+  const artifact = {
+    data: payload.body,
+    type: payload.type
+  }
+
+  // Sign the artifact and build the bundle
+  return initBundleBuilder(options).create(artifact)
+}
+
+// Assembles the Sigstore bundle builder with the appropriate options
+const initBundleBuilder = (opts: SignOptions): BundleBuilder => {
+  const identityProvider =
+    opts.identityProvider || new CIContextProvider(OIDC_AUDIENCE)
+  const timeout = opts.timeout || DEFAULT_TIMEOUT
+  const retry = opts.retry || DEFAULT_RETRIES
+  const witnesses: Witness[] = []
+
+  const signer = new FulcioSigner({
+    identityProvider: identityProvider,
+    fulcioBaseURL: opts.fulcioURL,
+    timeout: timeout,
+    retry: retry
+  })
+
+  if (opts.rekorURL) {
+    witnesses.push(
+      new RekorWitness({
+        rekorBaseURL: opts.rekorURL,
+        entryType: 'dsse',
+        timeout: timeout,
+        retry: retry
+      })
+    )
+  }
+
+  if (opts.tsaServerURL) {
+    witnesses.push(
+      new TSAWitness({
+        tsaBaseURL: opts.tsaServerURL,
+        timeout: timeout,
+        retry: retry
+      })
+    )
+  }
+
+  return new DSSEBundleBuilder({ signer, witnesses })
+}
--- a/packages/attest/src/store.ts
+++ b/packages/attest/src/store.ts
@ -0,0 +1,27 @@
+import * as github from '@actions/github'
+import fetch from 'make-fetch-happen'
+
+const CREATE_ATTESTATION_REQUEST = 'POST /repos/{owner}/{repo}/attestations'
+
+// Upload the attestation to the repository's attestations endpoint. Returns the
+// ID of the uploaded attestation.
+export const writeAttestation = async (
+  attestation: unknown,
+  token: string
+): Promise<string> => {
+  const octokit = github.getOctokit(token, { request: { fetch } })
+
+  try {
+    const response = await octokit.request(CREATE_ATTESTATION_REQUEST, {
+      owner: github.context.repo.owner,
+      repo: github.context.repo.repo,
+      data: { bundle: attestation }
+    })
+
+    return response.data?.id
+  } catch (err) {
+    /* istanbul ignore next */
+    const message = err instanceof Error ? err.message : err
+    throw new Error(`Failed to persist attestation: ${message}`)
+  }
+}
--- a/packages/attest/tsconfig.json
+++ b/packages/attest/tsconfig.json
@ -0,0 +1,18 @@
+{
+  "extends": "@tsconfig/node18/tsconfig.json",
+  "compilerOptions": {
+    "composite": true,
+    "rootDir": "src",
+    "outDir": "dist",
+    "declaration": true,
+    "noFallthroughCasesInSwitch": true,
+    "noImplicitOverride": true,
+    "allowUnreachableCode": false,
+    "noImplicitReturns": true,
+    "noUnusedParameters": true
+  },
+  "exclude": [
+    "./dist",
+    "**/__tests__"
+  ]
+}
--- a/src/main.ts
+++ b/src/main.ts
@ -1,5 +1,5 @@
+import { generateProvenancePredicate } from '@actions/attest'
 import * as core from '@actions/core'
-import { wait } from './wait'

 /**
 * The main function for the action.
@ -7,20 +7,14 @@ import { wait } from './wait'
 */
 export async function run(): Promise<void> {
  try {
-    const ms: string = core.getInput('milliseconds')
+    // Calculate subject from inputs and generate provenance
+    const predicate = generateProvenancePredicate(process.env)

-    // Debug logs are only output if the `ACTIONS_STEP_DEBUG` secret is true
-    core.debug(`Waiting ${ms} milliseconds ...`)
-
-    // Log the current timestamp, wait, then log the new timestamp
-    core.debug(new Date().toTimeString())
-    await wait(parseInt(ms, 10))
-    core.debug(new Date().toTimeString())
-
-    // Set outputs for other workflow steps to use
-    core.setOutput('time', new Date().toTimeString())
-  } catch (error) {
+    core.setOutput('predicate', predicate.params)
+    core.setOutput('predicate-type', predicate.type)
+  } catch (err) {
+    const error = err instanceof Error ? err : new Error(`${err}`)
    // Fail the workflow run if an error occurs
-    if (error instanceof Error) core.setFailed(error.message)
+    core.setFailed(error.message)
  }
 }
--- a/src/wait.ts
+++ b/src/wait.ts
@ -1,14 +0,0 @@
-/**
- * Wait for a number of milliseconds.
- * @param milliseconds The number of milliseconds to wait.
- * @returns {Promise<string>} Resolves with 'done!' after the wait is over.
- */
-export async function wait(milliseconds: number): Promise<string> {
-  return new Promise(resolve => {
-    if (isNaN(milliseconds)) {
-      throw new Error('milliseconds not a number')
-    }
-
-    setTimeout(() => resolve('done!'), milliseconds)
-  })
-}
--- a/tsconfig.json
+++ b/tsconfig.json
@ -15,5 +15,9 @@
    "skipLibCheck": true,
    "newLine": "lf"
  },
-  "exclude": ["./dist", "./node_modules", "./__tests__", "./coverage"]
+  "include": [ "/src/*" ],
+  "exclude": ["./dist", "./node_modules", "./__tests__", "./coverage"],
+  "references": [
+    { "path": "./packages/attest" }
+  ]
 }
				`@ -0,0 +1 @@`
				`export declare const writeAttestation: (attestation: unknown, token: string) => Promise<string>;`