AI‑Accelerated ISO 21434 Cybersecurity for Automotive Semiconductors

The challenge: ISO 21434 at semiconductor speed

Automotive semiconductor suppliers entering the OEM supply chain face a uniquely hard version of ISO 21434:

CSMS expectations apply immediately, even before a full vehicle program exists
TARAs must be repeated across products, variants, and customers
Evidence must be auditor‑grade, not exploratory
The work rarely lives in one place — architectures, assumptions, threat models, and mitigations are fragmented across teams and tools

In practice, this leads to a familiar outcome: strong security engineering teams spending the majority of their time assembling documentation rather than improving the system.

This post walks through a realistic end‑to‑end ISO 21434 Level‑2 TARA workflow for an automotive semiconductor platform, showing how teams can:

Fully satisfy CSMS and TARA auditor expectations
Maintain a single source of truth for workflow and status
Reduce hands‑on documentation effort by ~70% using AI

The solution pattern: structure + execution

The key insight is that ISO 21434 work has two very different jobs:

Workflow governance – defining what must exist, when, by whom, and in what state
Artifact execution – actually producing high‑quality TARAs, assumptions, threat scenarios, and mitigations

High‑performing teams separate these concerns.

In this use case:

A process‑centric platform manages the ISO 21434 CSMS lifecycle, roles, gates, and audit readiness
Saphira’s AI execution engine generates and iterates on the intermediate cybersecurity artifacts that normally consume weeks of expert time

Reference system: automotive SoC platform

For concreteness, we ground this walkthrough in a real automotive semiconductor scenario:

Product: Automotive‑grade SoC used in ADAS and centralized compute
Context: Deployed across multiple OEM programs
Interfaces: Cameras, radar, vehicle networks, OTA update pipeline
Security scope: Hardware root of trust, secure boot, firmware update, data paths

This example is derived from a real automotive TARA engagement; identifying details have been anonymized.

Step 1: ISO 21434 CSMS workflow (auditor view)

The cybersecurity program begins with a structured CSMS workflow aligned to ISO 21434, including:

Governance and responsibility assignment
Asset identification and security objectives
TARA definition and execution
Cybersecurity concept and requirements
Verification, validation, and monitoring

From an auditor’s perspective, this workflow must clearly show:

Who owns each activity
Status transitions (Draft → Review → Baseline)
Evidence traceability across lifecycle stages

This layer is intentionally tool‑agnostic with respect to content generation — its role is to ensure completeness and consistency.

Step 2: Defining TARA inputs (engineer view)

Rather than starting from blank threat tables, engineers provide high‑leverage inputs:

High‑level architecture diagrams (block‑level is sufficient)
Trust boundaries and interfaces
Operational assumptions and constraints
Safety and availability expectations

These inputs are exactly what engineers already have — but rarely exploit fully in traditional tools.

Step 3: AI‑assisted Level‑2 TARA generation

Using these inputs, Saphira generates a Level‑2 TARA aligned to ISO 21434, including:

Assets and security properties
Threat scenarios and attack paths
Impact and feasibility reasoning
Risk classification and prioritization

Crucially, this is not a one‑shot generation.

The system:

Flags ambiguous assumptions
Asks targeted clarification questions
Allows rapid iteration with the engineering team

This mirrors how real TARAs are developed — but collapses weeks of work into days.

Step 4: Traceability to cybersecurity requirements

Every generated threat scenario is automatically linked to:

Cybersecurity goals
Cybersecurity requirements
Allocations to HW, FW, and system controls

This traceability is preserved end‑to‑end, ensuring:

No orphaned threats
No unmotivated requirements
Clean evidence for audits and customer reviews

Step 5: CSMS completeness and audit readiness

From a CS auditor’s perspective, the result is a complete and inspectable CSMS:

All ISO 21434 activities accounted for
Clear ownership and baselined artifacts
Consistent rationale across documents

From the engineering team’s perspective:

Documentation effort reduced by ~70%
More time spent on actual design decisions
Faster response to OEM‑specific variations

Beyond ISO 21434: a unified compliance motion

A key advantage of this approach is that the same workflow foundation supports adjacent standards:

ASPICE 4.0 – aligned lifecycle and evidence
ISO 26262 – shared architecture and traceability
ISO 21448 (SOTIF) – reuse of operational assumptions
ISO 8800 – early AI‑related risk identification

Instead of parallel compliance efforts, teams work in a single, unified interface with a common expert model.

Why this matters for automotive semiconductor teams

For semiconductor suppliers scaling into automotive programs, this model:

De‑risks early OEM engagement
Improves audit outcomes
Dramatically lowers cost per TARA
Enables reuse across customers without copy‑paste

Most importantly, it allows security experts to focus on security, not paperwork.

What’s next

This use case represents an emerging pattern we are actively extending:

Deeper automation across cybersecurity concepts
Closer alignment between safety and security analyses
Faster adaptation to OEM‑specific interpretations

If you’re responsible for cybersecurity, safety, or compliance at an automotive semiconductor company and want to explore this approach, we’d love to compare notes.

All trademarks and product names are the property of their respective owners. This post describes a representative workflow and does not disclose customer‑confidential information.