implementing-supply-chain-security-with-in-toto

name	implementing-supply-chain-security-with-in-toto
description	Implement software supply chain integrity verification for container builds using the in-toto framework to create cryptographically signed attestations across CI/CD pipeline steps.
domain	cybersecurity
subdomain	container-security
tags	["in-toto","supply-chain-security","attestation","slsa","sigstore","container-security","cncf","provenance","sbom"]
version	1.0
author	mahipal
license	Apache-2.0
nist_csf	["PR.PS-01","PR.IR-01","ID.AM-08","DE.CM-01"]

Implementing Supply Chain Security with in-toto

Overview

in-toto is a CNCF graduated project that ensures the integrity of software supply chains from initiation to end-user installation. It creates a verifiable record of the entire software development lifecycle by generating cryptographically signed attestations (called "link metadata") at each step, proving what happened, who performed it, and what artifacts were produced. For container environments, in-toto verifies that images deployed to Kubernetes followed approved build processes and have not been tampered with.

When to Use

• When deploying or configuring implementing supply chain security with in toto 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

• Python 3.8+ or Go runtime for in-toto client libraries
• GPG or Ed25519 keys for signing attestations
• Container build pipeline (Docker, Buildah, or Kaniko)
• Container registry (Docker Hub, ECR, GCR, or Harbor)
• Kubernetes cluster for deployment verification

Core Concepts

Supply Chain Layout

The layout is the central policy document that defines:

• Steps: Ordered operations in the supply chain (clone, build, test, package, push)
• Functionaries: Authorized entities (people or CI systems) that perform each step
• Inspections: Client-side verification checks performed at verification time
• Expected artifacts: Input/output relationships between steps

from in_toto.models.layout import Layout, Step, Inspection
from securesystemslib.interface import import_ed25519_privatekey_from_file

# Create the supply chain layout
layout = Layout()
layout.set_relative_expiration(months=3)

# Define the code clone step
step_clone = Step(name="clone")
step_clone.expected_materials = []
step_clone.expected_products = [["CREATE", "src/*"]]
step_clone.pubkeys = [clone_functionary_keyid]
step_clone.expected_command = ["git", ]
step_clone.threshold = 


step_build = Step(name=)
step_build.expected_materials = [[, , , , , ]]
step_build.expected_products = [[, ]]
step_build.pubkeys = [build_functionary_keyid]
step_build.expected_command = [, ]
step_build.threshold = 


step_scan = Step(name=)
step_scan.expected_materials = [[, , , , , ]]
step_scan.expected_products = [[, ]]
step_scan.pubkeys = [scan_functionary_keyid]
step_scan.threshold = 

layout.steps = [step_clone, step_build, step_scan]