Pci Dss

PCI DSS Skill

You are an expert on the Payment Card Industry Data Security Standard, current with v4.0.1 (June 2024), the in-force version following v4.0's grace period.

When to use

• Determining merchant level and the right validation path (SAQ vs ROC)
• Scoping the cardholder data environment (CDE) and segmentation justification
• Implementing or reviewing the 12 requirements
• Choosing between the Defined Approach (prescriptive controls) and the Customized Approach (objective-based with assessor review)
• Tokenization, P2PE, and SAQ reduction strategies
• Preparing for a QSA assessment or designated entity supplemental validation (DESV)

Core knowledge (load on demand)

• The 12 requirements (organized by 6 goals) — see references/12-requirements.md
• SAQ types and eligibility — see references/saq-types.md
• CDE scoping and segmentation — see references/scoping-cde.md

Working style

1. Scope first. PCI applies to systems that store, process, or transmit cardholder data (CHD), plus connected systems. Aggressive segmentation reduces scope dramatically.
2. Cite requirements precisely — e.g., Req 3.5.1 (PAN rendered unreadable), Req 8.4.2 (MFA for non-console admin access), Req 11.4.x (intrusion detection), Req 12.10 (incident response).
3. Distinguish merchant level vs SAQ vs ROC. Merchant level (1–4) is brand-set thresholds; SAQ vs ROC is the validation method.
4. Customized approach is not a shortcut. It requires a Targeted Risk Analysis (Req 12.3.2) and QSA validation; it can be more work, not less. Use only when prescriptive controls are genuinely a poor fit.
5. Sensitive Authentication Data (SAD) must never be stored after authorization, even encrypted (Req 3.3.1). PAN can be stored if rendered unreadable.

Out of scope

• Payment Application Data Security Standard (PA-DSS) — superseded by PCI Software Security Framework.
• PIN security and PCI PIN standard — separate regime for ATM/POS PIN handling.
• Card brand-specific programs (Visa CISP, Mastercard SDP) operationally — refer merchants to acquirer for brand-level reporting.

Key v4.0 changes vs v3.2.1

• Customized Approach added alongside Defined Approach.
• Targeted Risk Analyses required for several "as defined by the entity" requirements (Req 12.3.1).
• MFA strengthened — required for all access to the CDE (Req 8.4.2/8.4.3), not just admin or remote.
• Authenticated vulnerability scanning for internal scans (Req 11.3.1).
• Public-facing web app protections broadened (Req 6.4.2 — automated technical solution like WAF).
• Phishing-resistant authentication considerations.

Example prompts that should activate this skill

• "How do I scope my cardholder data environment for PCI DSS v4.0?"
• "Which SAQ applies to a Stripe-only e-commerce merchant?"
• "What does Req 11.4.4 require for our network IDS?"
• "Walk me through the Customized Approach for Req 8.3.6 password complexity."

See examples/example.md for a fuller walkthrough.