implementing-code-signing-for-artifacts

name	implementing-code-signing-for-artifacts
description	This skill covers implementing code signing for build artifacts to ensure integrity and authenticity throughout the software supply chain. It addresses signing binaries, packages, and containers using GPG, Sigstore, and platform-specific signing tools, establishing trust chains, and verifying signatures in deployment pipelines.
domain	cybersecurity
subdomain	devsecops
tags	["devsecops","cicd","code-signing","supply-chain","sigstore","secure-sdlc"]
version	1.0.0
author	mahipal
license	Apache-2.0
nist_csf	["PR.PS-01","GV.SC-07","ID.IM-04","PR.PS-04"]
mitre_attack	["T1195","T1554","T1059.004","T1610","T1611"]
source	https://github.com/mukul975/Anthropic-Cybersecurity-Skills
source_commit	04450304b12645cb2b974ab96d28c0664758a88d

Implementing Code Signing for Artifacts

When to Use

• When establishing artifact integrity verification to prevent supply chain tampering
• When compliance requires cryptographic proof that build artifacts are authentic and unmodified
• When distributing software to customers who need to verify publisher identity
• When implementing zero-trust deployment pipelines that reject unsigned artifacts
• When meeting SLSA Level 2+ requirements for provenance and integrity

Do not use for encrypting artifacts (signing provides integrity, not confidentiality), for container image signing specifically (use cosign), or for source code authentication (use commit signing).

Prerequisites

• GPG key pair for traditional signing or Sigstore account for keyless signing
• Code signing certificate from a Certificate Authority for public distribution
• CI/CD pipeline with access to signing keys or identity provider
• Verification infrastructure in deployment pipelines

Workflow

Step 1: Generate and Manage Signing Keys

# Generate GPG key for artifact signing
gpg --full-generate-key --batch <<EOF
Key-Type: eddsa
Key-Curve: ed25519
Subkey-Type: eddsa
Subkey-Curve: ed25519
Name-Real: CI Build System
Name-Email: [e-mail]
Expire-Date: 1y
%no-protection
EOF

# Export public key for distribution
gpg --armor --export [e-mail] > signing-key.pub

# Export private key for CI/CD (store in secrets manager)
gpg --armor --export-secret-keys [e-mail] > signing-key.priv

Step 2: Sign Build Artifacts in CI/CD

# .github/workflows/build-sign.yml
name: Build and Sign

on:
  push:
    tags: ['v*']

jobs:
  build-sign:
    runs-on: ubuntu-latest
    permissions:
      contents: write
      id-token: