＋ Add to collection

Install (CLI)

npx skillmds add mukul975/implementing-image-provenance-verification-with-cosign

Or Copy and Paste in Your Agent chat

Please install the Agent Skill "mukul975/implementing-image-provenance-verification-with-cosign" for me from skillmd.com. A SkillMD skill is a SKILL.md file — plain markdown plus a few companion files — that you save into my skills directory. Use whichever fetch route fits your setup: (1) if you have a terminal, run npx -y skillmds add mukul975/implementing-image-provenance-verification-with-cosign; (2) otherwise fetch the file manifest at https://api.skillmd.com/api/skills/mukul975/implementing-image-provenance-verification-with-cosign/bundle?format=manifest and download each listed file from its "url" into implementing-image-provenance-verification-with-cosign/ in your skills directory; (3) if the SkillMD MCP tools are connected, call skillmd_download with slug "mukul975/implementing-image-provenance-verification-with-cosign" and save the returned files under implementing-image-provenance-verification-with-cosign/. Show me the SKILL.md before saving if you'd like me to review it. If your skills directory is read-only (e.g. the Claude desktop app), save the files to a working folder instead and tell me — I'll add them through my app's skills settings.

README badge

Show this skill's registry status in your repo:

[![SkillMD](https://skillmd.com/badge/mukul975/implementing-image-provenance-verification-with-cosign.svg)](https://skillmd.com/skills/mukul975/implementing-image-provenance-verification-with-cosign)

implementing-image-provenance-verification-with-cosign

Name: implementing-image-provenance-verification-with-cosign
Rating: 4.2 (5 reviews)
Author: mukul975

mukul975/implementing-image-provenance-verification-with-cosign · Agent Skill (multi-file)

by mukul975 · bundle

Published Jul 5, 2026 · Last updated Jul 6, 2026

Sign and verify container image provenance using Sigstore Cosign with keyless OIDC-based signing, attestations, and Kubernetes admission enforcement.

SKILL.md

Implementing Image Provenance Verification with Cosign

Overview

Cosign is a Sigstore tool for signing, verifying, and attaching metadata to container images and OCI artifacts. It supports both key-based and keyless (OIDC) signing, integrates with Fulcio (certificate authority) and Rekor (transparency log), and enables supply chain security for container images.

When to Use

When deploying or configuring implementing image provenance verification with cosign capabilities in your environment
When establishing security controls aligned to compliance requirements
When building or improving security architecture for this domain
When conducting security assessments that require this implementation

Prerequisites

Cosign CLI installed
Docker or Podman for building images
OCI-compliant container registry (Docker Hub, GHCR, GCR, ECR)
OIDC provider account (GitHub, Google, Microsoft) for keyless signing

Installing Cosign

# Install via Go
go install github.com/sigstore/cosign/v2/cmd/cosign@latest

# Install via Homebrew
brew install cosign

# Install via script
curl -O -L "https://github.com/sigstore/cosign/releases/latest/download/cosign-linux-amd64"
sudo mv cosign-linux-amd64 /usr/local/bin/cosign
sudo chmod +x /usr/local/bin/cosign

# Verify installation
cosign version

Key-Based Signing

Generate Key Pair

# Generate cosign key pair (creates cosign.key and cosign.pub)
cosign generate-key-pair

# Generate key pair stored in KMS
cosign generate-key-pair --kms awskms:///alias/cosign-key
cosign generate-key-pair --kms gcpkms://projects/PROJECT/locations/LOCATION/keyRings/KEYRING/cryptoKeys/KEY
cosign generate-key-pair --kms hashivault://transit/keys/cosign

Sign Image with Key

# Sign an image
cosign sign --key cosign.key ghcr.io/myorg/myapp:v1.0.0

# Sign with annotations
cosign sign --key cosign.key \
  -a "build-id=12345" \
  -a "git-sha=$(git rev-parse HEAD)" \
  ghcr.io/myorg/myapp:v1.0.0

Verify Image with Key

# Verify signature
cosign verify --key cosign.pub ghcr.io/myorg/myapp:v1.0.0

# Verify with annotation check
cosign verify --key cosign.pub \
  -a "build-id=12345" \
  ghcr.io/myorg/myapp:v1.0.0

Keyless Signing (OIDC)

Sign with Keyless (Interactive)

# Keyless sign - opens browser for OIDC auth
cosign sign ghcr.io/myorg/myapp:v1.0.0

# The signature, certificate, and Rekor entry are created automatically

Sign with Keyless (CI/CD - Non-Interactive)

# GitHub Actions (uses OIDC token automatically)
cosign sign ghcr.io/myorg/myapp:v1.0.0 \
  --yes

# With explicit identity token
cosign sign ghcr.io/myorg/myapp:v1.0.0 \
  --identity-token=$(cat /var/run/sigstore/cosign/oidc-token) \
  --yes

Verify Keyless Signature

# Verify by email identity
cosign verify ghcr.io/myorg/myapp:v1.0.0 \
  --certificate-identity=builder@example.com \
  --certificate-oidc-issuer=https://accounts.google.com

# Verify by GitHub Actions workflow
cosign verify ghcr.io/myorg/myapp:v1.0.0 \
  --certificate-identity=https://github.com/myorg/myrepo/.github/workflows/build.yml@refs/heads/main \
  --certificate-oidc-issuer=https://token.actions.githubusercontent.com

# Verify with regex matching
cosign verify ghcr.io/myorg/myapp:v1.0.0 \
  --certificate-identity-regexp=".*@example.com" \
  --certificate-oidc-issuer=https://accounts.google.com

Attestations (SLSA Provenance)

Attach SBOM Attestation

# Generate SBOM
syft ghcr.io/myorg/myapp:v1.0.0 -o cyclonedx-json > sbom.cdx.json

# Attach SBOM as attestation
cosign attest --key cosign.key \
  --type cyclonedx \
  --predicate sbom.cdx.json \
  ghcr.io/myorg/myapp:v1.0.0

# Verify attestation
cosign verify-attestation --key cosign.pub \
  --type cyclonedx \
  ghcr.io/myorg/myapp:v1.0.0

Attach Vulnerability Scan Attestation

# Run scan and save results
grype ghcr.io/myorg/myapp:v1.0.0 -o json > vuln-scan.json

# Attach scan results as attestation
cosign attest --key cosign.key \
  --type vuln \
  --predicate vuln-scan.json \
  ghcr.io/myorg/myapp:v1.0.0

SLSA Provenance Attestation

# Attach SLSA provenance
cosign attest --key cosign.key \
  --type slsaprovenance \
  --predicate provenance.json \
  ghcr.io/myorg/myapp:v1.0.0

# Verify SLSA provenance
cosign verify-attestation --key cosign.pub \
  --type slsaprovenance \
  ghcr.io/myorg/myapp:v1.0.0

CI/CD Integration

GitHub Actions

name: Sign and Publish
on:
  push:
    tags: ['v*']

permissions:
  contents: read
  packages: write
  id-token: write  # Required for keyless signing

jobs:
  build-sign:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: sigstore/cosign-installer@v3

      - name: Login to GHCR
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build and push
        id: build
        uses: docker/build-push-action@v5
        with:
          push: true
          tags: ghcr.io/${{ github.repository }}:${{ github.ref_name }}

      - name: Sign image (keyless)
        run: |
          cosign sign --yes \
            ghcr.io/${{ github.repository }}@${{ steps.build.outputs.digest }}

      - name: Generate and attach SBOM
        run: |
          syft ghcr.io/${{ github.repository }}@${{ steps.build.outputs.digest }} -o cyclonedx-json > sbom.json
          cosign attest --yes \
            --type cyclonedx \
            --predicate sbom.json \
            ghcr.io/${{ github.repository }}@${{ steps.build.outputs.digest }}

Kubernetes Admission Enforcement

Policy Controller (Sigstore)

# Install policy-controller
helm repo add sigstore https://sigstore.github.io/helm-charts
helm install policy-controller sigstore/policy-controller \
  --namespace cosign-system --create-namespace

# Enforce signed images in namespace
apiVersion: policy.sigstore.dev/v1beta1
kind: ClusterImagePolicy
metadata:
  name: require-signed-images
spec:
  images:
    - glob: "ghcr.io/myorg/**"
  authorities:
    - keyless:
        url: https://fulcio.sigstore.dev
        identities:
          - issuer: https://token.actions.githubusercontent.com
            subjectRegExp: "https://github.com/myorg/.*"
      ctlog:
        url: https://rekor.sigstore.dev

Kyverno Integration

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: verify-image-signature
spec:
  validationFailureAction: Enforce
  rules:
    - name: verify-cosign-signature
      match:
        any:
          - resources:
              kinds: ["Pod"]
      verifyImages:
        - imageReferences:
            - "ghcr.io/myorg/*"
          attestors:
            - entries:
                - keyless:
                    subject: "https://github.com/myorg/*"
                    issuer: "https://token.actions.githubusercontent.com"
                    rekor:
                      url: https://rekor.sigstore.dev

Transparency Log (Rekor)

# Search Rekor for image signatures
rekor-cli search --email builder@example.com

# Get specific entry
rekor-cli get --uuid <entry-uuid>

# Verify entry inclusion
cosign verify ghcr.io/myorg/myapp:v1.0.0 \
  --certificate-identity=builder@example.com \
  --certificate-oidc-issuer=https://accounts.google.com

Best Practices

Use keyless signing in CI/CD for automated pipelines
Sign by digest not by tag for immutable references
Attach SBOM attestations alongside signatures
Enforce signatures at admission with policy-controller or Kyverno
Use OIDC identity verification instead of just key verification
Store keys in KMS (AWS KMS, GCP KMS, HashiCorp Vault) for key-based signing
Verify the full chain: signature + certificate + Rekor inclusion
Include build metadata as annotations on signatures

---
name: implementing-image-provenance-verification-with-cosign
description: Sign and verify container image provenance using Sigstore Cosign with keyless OIDC-based signing, attestations, and Kubernetes admission enforcement.
license: Apache-2.0
---

# Implementing Image Provenance Verification with Cosign

## Overview

Cosign is a Sigstore tool for signing, verifying, and attaching metadata to container images and OCI artifacts. It supports both key-based and keyless (OIDC) signing, integrates with Fulcio (certificate authority) and Rekor (transparency log), and enables supply chain security for container images.


## When to Use

- When deploying or configuring implementing image provenance verification with cosign capabilities in your environment
- When establishing security controls aligned to compliance requirements
- When building or improving security architecture for this domain
- When conducting security assessments that require this implementation

## Prerequisites

- Cosign CLI installed
- Docker or Podman for building images
- OCI-compliant container registry (Docker Hub, GHCR, GCR, ECR)
- OIDC provider account (GitHub, Google, Microsoft) for keyless signing

## Installing Cosign

```bash
# Install via Go
go install github.com/sigstore/cosign/v2/cmd/cosign@latest

# Install via Homebrew
brew install cosign

# Install via script
curl -O -L "https://github.com/sigstore/cosign/releases/latest/download/cosign-linux-amd64"
sudo mv cosign-linux-amd64 /usr/local/bin/cosign
sudo chmod +x /usr/local/bin/cosign

# Verify installation
cosign version
```

## Key-Based Signing

### Generate Key Pair

```bash
# Generate cosign key pair (creates cosign.key and cosign.pub)
cosign generate-key-pair

# Generate key pair stored in KMS
cosign generate-key-pair --kms awskms:///alias/cosign-key
cosign generate-key-pair --kms gcpkms://projects/PROJECT/locations/LOCATION/keyRings/KEYRING/cryptoKeys/KEY
cosign generate-key-pair --kms hashivault://transit/keys/cosign
```

### Sign Image with Key

```bash
# Sign an image
cosign sign --key cosign.key ghcr.io/myorg/myapp:v1.0.0

# Sign with annotations
cosign sign --key cosign.key \
  -a "build-id=12345" \
  -a "git-sha=$(git rev-parse HEAD)" \
  ghcr.io/myorg/myapp:v1.0.0
```

### Verify Image with Key

```bash
# Verify signature
cosign verify --key cosign.pub ghcr.io/myorg/myapp:v1.0.0

# Verify with annotation check
cosign verify --key cosign.pub \
  -a "build-id=12345" \
  ghcr.io/myorg/myapp:v1.0.0
```

## Keyless Signing (OIDC)

### Sign with Keyless (Interactive)

```bash
# Keyless sign - opens browser for OIDC auth
cosign sign ghcr.io/myorg/myapp:v1.0.0

# The signature, certificate, and Rekor entry are created automatically
```

### Sign with Keyless (CI/CD - Non-Interactive)

```bash
# GitHub Actions (uses OIDC token automatically)
cosign sign ghcr.io/myorg/myapp:v1.0.0 \
  --yes

# With explicit identity token
cosign sign ghcr.io/myorg/myapp:v1.0.0 \
  --identity-token=$(cat /var/run/sigstore/cosign/oidc-token) \
  --yes
```

### Verify Keyless Signature

```bash
# Verify by email identity
cosign verify ghcr.io/myorg/myapp:v1.0.0 \
  --certificate-identity=builder@example.com \
  --certificate-oidc-issuer=https://accounts.google.com

# Verify by GitHub Actions workflow
cosign verify ghcr.io/myorg/myapp:v1.0.0 \
  --certificate-identity=https://github.com/myorg/myrepo/.github/workflows/build.yml@refs/heads/main \
  --certificate-oidc-issuer=https://token.actions.githubusercontent.com

# Verify with regex matching
cosign verify ghcr.io/myorg/myapp:v1.0.0 \
  --certificate-identity-regexp=".*@example.com" \
  --certificate-oidc-issuer=https://accounts.google.com
```

## Attestations (SLSA Provenance)

### Attach SBOM Attestation

```bash
# Generate SBOM
syft ghcr.io/myorg/myapp:v1.0.0 -o cyclonedx-json > sbom.cdx.json

# Attach SBOM as attestation
cosign attest --key cosign.key \
  --type cyclonedx \
  --predicate sbom.cdx.json \
  ghcr.io/myorg/myapp:v1.0.0

# Verify attestation
cosign verify-attestation --key cosign.pub \
  --type cyclonedx \
  ghcr.io/myorg/myapp:v1.0.0
```

### Attach Vulnerability Scan Attestation

```bash
# Run scan and save results
grype ghcr.io/myorg/myapp:v1.0.0 -o json > vuln-scan.json

# Attach scan results as attestation
cosign attest --key cosign.key \
  --type vuln \
  --predicate vuln-scan.json \
  ghcr.io/myorg/myapp:v1.0.0
```

### SLSA Provenance Attestation

```bash
# Attach SLSA provenance
cosign attest --key cosign.key \
  --type slsaprovenance \
  --predicate provenance.json \
  ghcr.io/myorg/myapp:v1.0.0

# Verify SLSA provenance
cosign verify-attestation --key cosign.pub \
  --type slsaprovenance \
  ghcr.io/myorg/myapp:v1.0.0
```

## CI/CD Integration

### GitHub Actions

```yaml
name: Sign and Publish
on:
  push:
    tags: ['v*']

permissions:
  contents: read
  packages: write
  id-token: write  # Required for keyless signing

jobs:
  build-sign:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: sigstore/cosign-installer@v3

      - name: Login to GHCR
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build and push
        id: build
        uses: docker/build-push-action@v5
        with:
          push: true
          tags: ghcr.io/${{ github.repository }}:${{ github.ref_name }}

      - name: Sign image (keyless)
        run: |
          cosign sign --yes \
            ghcr.io/${{ github.repository }}@${{ steps.build.outputs.digest }}

      - name: Generate and attach SBOM
        run: |
          syft ghcr.io/${{ github.repository }}@${{ steps.build.outputs.digest }} -o cyclonedx-json > sbom.json
          cosign attest --yes \
            --type cyclonedx \
            --predicate sbom.json \
            ghcr.io/${{ github.repository }}@${{ steps.build.outputs.digest }}
```

## Kubernetes Admission Enforcement

### Policy Controller (Sigstore)

```bash
# Install policy-controller
helm repo add sigstore https://sigstore.github.io/helm-charts
helm install policy-controller sigstore/policy-controller \
  --namespace cosign-system --create-namespace
```

```yaml
# Enforce signed images in namespace
apiVersion: policy.sigstore.dev/v1beta1
kind: ClusterImagePolicy
metadata:
  name: require-signed-images
spec:
  images:
    - glob: "ghcr.io/myorg/**"
  authorities:
    - keyless:
        url: https://fulcio.sigstore.dev
        identities:
          - issuer: https://token.actions.githubusercontent.com
            subjectRegExp: "https://github.com/myorg/.*"
      ctlog:
        url: https://rekor.sigstore.dev
```

### Kyverno Integration

```yaml
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: verify-image-signature
spec:
  validationFailureAction: Enforce
  rules:
    - name: verify-cosign-signature
      match:
        any:
          - resources:
              kinds: ["Pod"]
      verifyImages:
        - imageReferences:
            - "ghcr.io/myorg/*"
          attestors:
            - entries:
                - keyless:
                    subject: "https://github.com/myorg/*"
                    issuer: "https://token.actions.githubusercontent.com"
                    rekor:
                      url: https://rekor.sigstore.dev
```

## Transparency Log (Rekor)

```bash
# Search Rekor for image signatures
rekor-cli search --email builder@example.com

# Get specific entry
rekor-cli get --uuid <entry-uuid>

# Verify entry inclusion
cosign verify ghcr.io/myorg/myapp:v1.0.0 \
  --certificate-identity=builder@example.com \
  --certificate-oidc-issuer=https://accounts.google.com
```

## Best Practices

1. **Use keyless signing** in CI/CD for automated pipelines
2. **Sign by digest** not by tag for immutable references
3. **Attach SBOM attestations** alongside signatures
4. **Enforce signatures** at admission with policy-controller or Kyverno
5. **Use OIDC identity** verification instead of just key verification
6. **Store keys in KMS** (AWS KMS, GCP KMS, HashiCorp Vault) for key-based signing
7. **Verify the full chain**: signature + certificate + Rekor inclusion
8. **Include build metadata** as annotations on signatures

Files

This skill is a package of 8 files. Install with the command above, or download the folder.

📄SKILL.md entry
📁assets
📄template.md 1.3 KB
📁references
📄api-reference.md 1.9 KB
📄standards.md 1.3 KB
📄workflows.md 1.2 KB
📁scripts
⚙️agent.py 7.5 KB
⚙️process.py 6.0 KB
📄LICENSE 11.0 KB

mukul975/Anthropic-Cybersecurity-Skills/tree/main/skills/implementing-image-provenance-verification-with-cosign commit · 673da1f3b0

▌
securing-container-registry-images · mukul975 bundle
Scan container images for vulnerabilities with Trivy and Grype, generate SBOMs, sign images with Cosign and Sigstore, configure registry access controls, and enforce security gates in CI/CD pipelines.

24.6k
repo stars
▌
implementing-code-signing-for-artifacts · mukul975 bundle
Sign build artifacts (binaries, packages, containers) with GPG, Sigstore, and platform-specific tools to ensure integrity and authenticity throughout the software supply chain.

24.6k
repo stars
▌
verifying-build-provenance-with-slsa-sigstore · mukul975 bundle
Verify signed artifacts and SLSA build provenance with Sigstore cosign and slsa-verifier, enforce keyless OIDC identity, and apply SLSA Build levels to harden the software supply chain.

24.6k
repo stars
▌
implementing-sigstore-for-software-signing · mukul975 bundle
Signs and verifies software artifacts using Sigstore's keyless signing, Rekor transparency log, and Fulcio certificate authority, integrating into CI/CD pipelines and Kubernetes admission controls.

24.6k
repo stars
▌
implementing-supply-chain-security-with-in-toto · mukul975 bundle
Verify container image integrity across CI/CD pipelines using the in-toto framework to generate and check cryptographically signed attestations.

24.6k
repo stars
▌
implementing-aqua-security-for-container-scanning · mukul975 bundle
Deploy Aqua Security's Trivy scanner to detect vulnerabilities, misconfigurations, secrets, and license issues in container images across CI/CD pipelines and registries.

24.6k
repo stars

Frequently asked questions

How do I install the implementing-image-provenance-verification-with-cosign skill?

Run npx skillmds add mukul975/implementing-image-provenance-verification-with-cosign in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

What does the implementing-image-provenance-verification-with-cosign skill do?

Sign and verify container image provenance using Sigstore Cosign with keyless OIDC-based signing, attestations, and Kubernetes admission enforcement. It is listed under DevOps & Infra, Security, CI/CD, Containers & Kubernetes, Secure Coding on SkillMD.

Is implementing-image-provenance-verification-with-cosign safe to use?

SkillMD's automated safety review verdict for this skill is CAUTION. Independent scanners report: SkillSpector: PASS, Skill Scanner: PASS. Capability flags: executes scripts, makes network calls, reads secrets. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with implementing-image-provenance-verification-with-cosign?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is implementing-image-provenance-verification-with-cosign free to use?

Yes. Installing skills from SkillMD is free. This skill is licensed under Apache-2.

Who published implementing-image-provenance-verification-with-cosign?

mukul975 (@mukul975) published this skill. Their other Agent Skills are listed on their SkillMD profile.