資安概念 (Cybersecurity Concept)
是什麼？
Important
「為了達成 CS Goals，在概念層級規劃的解決方案」。
介於「目標」與「技術細節」之間的橋樑。
Concept Phase 的四件套關係
Item Definition
↓
TARA (Clause 15)
↓
Cybersecurity Goals (Clause 9.4)
+
Cybersecurity Claims (Clause 9.5)
↓
Cybersecurity Concept (Clause 9.5) ← 概念解決方案
↓
Cybersecurity Requirements (Clause 10) ← 可實作的需求
CS Concept 內容
cybersecurity_concept:
item: "TCU-2026"
version: 1.0
for_each_cs_goal:
- cs_goal: CG-001 (Firmware integrity)
concept_solution:
- approach: "Secure boot chain + signed updates"
- mechanisms:
- "ROM-based boot loader verifies bootloader signature"
- "Bootloader verifies application signature before execution"
- "OTA payloads signed by OEM signing key"
- "Signature keys in HSM (no extraction)"
- constraints:
- "Must support post-quantum migration path"
- "Boot time < 500ms (vehicle requirement)"
- assumptions:
- "HSM is provisioned at production with unique device key"
- "OEM signing infrastructure is secured (separate item)"
- cs_goal: CG-002 (Cellular link confidentiality)
concept_solution:
- approach: "TLS 1.3 with certificate pinning + per-device key"
- mechanisms:
- "TLS 1.3 mandated; older versions rejected"
- "Server certificate pinning to OEM backend CA"
- "Client certificate per device (provisioned at production)"
- "Perfect Forward Secrecy via ECDHE"
- constraints:
- "Must work with 4G fallback when 5G unavailable"
for_each_cs_claim:
- cs_claim: CL-001 (OBD physical security)
validation_approach:
- "Operational guidance to vehicle owner"
- "Secondary protection: OBD diagnostic Security Access (UDS 0x27)"
CS Concept 的「層次」
Functional Concept（功能性概念）
└── 「會用什麼方法達成」
範例：「使用 secure boot + signed update」
Technical Concept（技術性概念，可選此階段或下階段）
└── 「具體技術選擇」
範例：「使用 ECDSA P-256 + SHA-256」
Tip
ISO 21434 不強制兩者切分。常見作法：
- Functional Concept 在 Concept Phase（Clause 9）
- Technical 細化 在 Product Development（Clause 10）
CS Concept 應涵蓋的層面
1. 保護機制 (Protection Mechanisms)
├── 預防 (Prevention)：如加密、簽章、權限
├── 偵測 (Detection)：如 IDS、Log 監控
└── 反應 (Response)：如降級、隔離
2. 多層防禦 (Defense in Depth)
├── 不依賴單一機制
└── 失效時的 fallback
3. 攻擊面降低 (Attack Surface Reduction)
├── 移除不必要的功能/介面
└── 最小化權限
4. 監控與審計
├── Log 機制
└── 異常通報
CS Concept 與架構設計的關係
CS Concept (Clause 9)
↓
(進入 Clause 10)
↓
Security Architecture
↓
各元件分配責任
↓
每個元件的 CS Requirements
↓
實作
CS Concept 範例（簡化）
┌────────────────────────────┐
│ Cybersecurity Concept │
│ for TCU-2026 │
└─────────────┬───────────────┘
│
┌─────────────────────┼─────────────────────┐
↓ ↓ ↓
┌───────────┐ ┌───────────┐ ┌───────────┐
│ Boot Chain │ │ Comms │ │ Update │
│ Security │ │ Security │ │ Security │
└─────┬─────┘ └─────┬─────┘ └─────┬─────┘
│ │ │
┌─────┴─────┐ ┌─────┴─────┐ ┌─────┴─────┐
│ Secure │ │ TLS │ │ Signed │
│ Boot │ │ 1.3 │ │ Image │
├──────────┤ ├──────────┤ ├───────────┤
│ Cert Chain│ │ Cert Pin │ │ Anti-Roll │
│ in ROM │ │ + mTLS │ │ -back │
├──────────┤ ├──────────┤ ├───────────┤
│ HSM-backed│ │ ECDHE PFS│ │ HSM Sig │
│ verify │ │ │ │ Verify │
└──────────┘ └──────────┘ └───────────┘
CS Concept 的批准與凍結
TARA 完成
↓
CS Goals draft
↓
CS Concept v0.x（多輪 review）
↓
與 Safety Concept 對齊
↓
CS Concept v1.0 baselined
↓
進入 Clause 10 Product Development
Warning
CS Concept 一旦 baseline，變更需經變更管理（影響 TARA 與 CS Case）。
證照考點
高頻考點
- CS Concept 介於 Goal 與 Requirement 之間
- 包含：保護機制、Defense in Depth、攻擊面降低、監控
- CS Concept 是 Cybersecurity Case 的設計論證
- 變更需經影響評估
- CS Concept 是 Clause 9 的核心 WP
- CS Concept 須與 Safety Concept 對齊
Related Notes
- 06-Concept-Phase/01-Item-Definition
- 06-Concept-Phase/02-Cybersecurity-Goals
- 06-Concept-Phase/03-Cybersecurity-Claims
- 07-Product-Development/01-Design-Requirements
- 12-TARA-Methods/01-TARA-Overview