📘 PKI (CISSP Exam Survival)

📘 PKI Crash-Memory Guide (CISSP Exam Survival)

✅ Designed for test day memorization
🧠 Anchored to CISSP Domains
🎯 Focused on key exam facts

🔐 What is PKI?

Public Key Infrastructure (PKI) is the framework that manages digital certificates and asymmetric key pairs to enable secure communication.

Appears in:

  • ✅ Domain 3: Security Architecture and Engineering

  • ✅ Domain 5: Identity and Access Management (IAM)

  • ✅ Domain 7: Security Operations (for revocation, incident response)

🔑 1. Public/Private Key Basics

Action Key Used Purpose
Encrypt Receiver’s Public Key 🔒 Confidentiality
Decrypt Receiver’s Private Key
Sign Sender’s Private Key ✍️ Integrity, Non-repudiation
Verify Signature Sender’s Public Key 🧾 Authentication

💡 Mnemonic:
"Public encrypts, private decrypts. Private signs, public verifies."

🏛 2. PKI Core Components

Component Function CISSP Domain
CA (Certificate Authority) Issues and signs digital certs D3, D5
RA (Registration Authority) Verifies identity before cert issuance D5
CRL (Certificate Revocation List) Publishes revoked certificates (slow) D7
OCSP (Online Cert Status Protocol) Real-time cert validation (fast) D7
X.509 Certificate Digital ID containing subject, public key, issuer, etc. D3

🧠 Certificate = Signed statement binding a public key to an identity.

🔄 3. Trust Models in PKI

Model How It Works Common Use
Hierarchical Root CA → Intermediate CA → End Entity Most secure (e.g., TLS)
Web of Trust Peer-to-peer trust, manual signing PGP
Bridge CA Links multiple CAs together Gov/military cross-certification

Appears in: Domain 3, Domain 5

⛔ 4. Revocation vs Expiration

Concept Description Domain
Expiration Cert is no longer valid after date D7
Revocation Cert is invalidated before expiration (compromised) D7
CRL List published by CA — checked by clients D7
OCSP Real-time API check for revocation D7

⚙️ 5. PKI in Practice

  • Digital Signature:

    • Signed with private key

    • Verified with public key

    • Provides authentication, integrity, non-repudiation

  • Confidential Message:

    • Encrypted with receiver’s public key

    • Decrypted with receiver’s private key

Appears in: Domain 3 (crypto), Domain 5 (IAM), Domain 7 (incident response)

🧠 6. Symmetric vs Asymmetric (Quick Recap)

Feature Symmetric Asymmetric
Keys Same key Key pair (public/private)
Speed Fast Slower
Use Case Encrypt bulk data Key exchange, signatures
Algorithms AES, DES RSA, ECC

🔁 7. Memory Drill: One-Minute Recall

Say this out loud 3x:

"Public encrypts, private decrypts.
Private signs, public verifies.
CA issues, RA validates, CRL revokes.
Trust the chain or it breaks."

🧾 8. Flashcard Summary (Exam Ready)

Question Answer
What does PKI manage? Asymmetric key pairs and digital certificates
What does a CA do? Issues and signs certificates
What provides real-time revocation status? OCSP
What is the standard format for certs? X.509
What provides non-repudiation in PKI? Digital signatures (private key used to sign)
Which key encrypts data sent to someone? Their public key
Which key is used to verify a digital signature? The sender’s public key

Comments

Post a Comment

Popular posts from this blog

🧭 CISSP Study Note: Guidelines

🧭 CISSP Study Note: Guidelines 🔍 Definition Guidelines are suggested practices, recommendations, or expectations that help individuals or teams perform tasks effectively and consistently to achieve organizational goals, standards, and strategic objectives . Unlike policies or standards, guidelines are not mandatory —they offer flexibility while still encouraging best practices. 🧠 Why It Matters in Cybersecurity In a security framework, not every situation can be addressed with a rigid rule . Guidelines fill that gap by offering direction without strict enforcement , helping professionals: Make informed decisions Handle exceptions responsibly Align behavior with organizational goals Maintain consistency across teams They also support user education, secure configurations, and best practices adoption without limiting operational flexibility. 📋 Guidelines vs. Policies vs. Standards Term Binding? Purpose Policy ✅ Mandatory Defines what must be...
Read more

💸 CISSP Study Note: Risk Transference

 💸 CISSP Study Note: Risk Transference 🔍 Definition Risk Transference is the process of shifting the financial or operational impact of a risk to a third party , typically through contracts, insurance, or outsourcing agreements . While the risk itself doesn’t disappear, its burden is transferred , meaning someone else becomes responsible for managing or absorbing the consequences . 🧠 Why It Matters in Cybersecurity Not all risks are feasible to mitigate or avoid directly—especially high-cost, low-probability events . Risk transference allows organizations to: Focus on their core competencies Offload specialized or high-risk tasks Limit financial exposure Improve recovery options without investing heavily in in-house controls 📌 Transference does NOT eliminate the risk—it shifts the responsibility or financial impact. 🧾 Common Methods of Risk Transference Method Description Cybersecurity Insurance Transfers financial losses from cyberattack...
Read more

📏 CISSP Study Note: Standards

📏 CISSP Study Note: Standards 🔍 Definition Standards are specific, mandatory rules or technical specifications that define how policies must be implemented and how performance or behavior must conform to meet organizational or regulatory expectations. They are non-negotiable , measurable, and enforceable, often serving as the baseline for procedures and audits . While policies tell you what to do, standards tell you exactly how it must be done. 🧠 Why It Matters in Cybersecurity Standards are critical for ensuring consistency , reliability , and compliance across systems, teams, and departments. They help: Reduce ambiguity in control implementation Align practices with compliance frameworks Support repeatable, auditable processes Simplify training, onboarding, and cross-team coordination 🧩 Standards in the Policy Hierarchy Level Purpose Policy High-level directive—“What must be done” Standard ✅ Mandatory specification—“How it must ...
Read more