CompTIA Section 8 – Cryptographic Solutions

Cryptographic Solutions – Detailed Study Revision Guide

Core Objectives

• Explain and distinguish between symmetric and asymmetric encryption algorithms.
• Understand key management lifecycle and its impact on secure communications.
• Evaluate hashing algorithms and their application in integrity assurance.
• Understand the structure and purpose of digital signatures and PKI.
• Compare data protection mechanisms at rest, in transit, and in use.
• Identify and explain cryptographic vulnerabilities and related attacks.

1. Cryptographic Fundamentals

Symmetric Encryption

• Uses one key for both encryption and decryption.
• Examples: AES (standard), DES (deprecated), Blowfish, ChaCha20
• Efficient for bulk data encryption.
• Drawback: Requires secure key exchange method.

Asymmetric Encryption

• Uses key pairs (public/private).
• Examples: RSA (widespread), ECC (efficient), Diffie-Hellman (key exchange)
• Enables digital signatures and non-repudiation.
• Slower than symmetric but critical for secure negotiation.

2. Hashing Algorithms

• Converts data into a fixed-length hash value.
• One-way: cannot be decrypted.
• Common algorithms: MD5 (obsolete), SHA-1 (insecure), SHA-256 (recommended)
• Applications: Password storage, digital signatures, file integrity verification
• Properties: Deterministic, collision-resistant, fast computation

3. Digital Signatures

• Hash of message is encrypted with sender’s private key.
• Recipient uses sender’s public key to verify authenticity.
• Ensures integrity, authenticity, and non-repudiation.
• Often used in software distribution and secure email.

4. Public Key Infrastructure (PKI)

• Framework for managing digital certificates and key pairs.
• Key components:
  • Certificate Authority (CA) – issues certificates
  • Registration Authority (RA) – verifies identities
  • Certificate Revocation List (CRL)
  • Online Certificate Status Protocol (OCSP)
• Trust model: Hierarchical vs. Web of Trust

5. Encryption Use Cases

Data at Rest

• Protects stored data (e.g., disk, file, database encryption)
• Tools: BitLocker, VeraCrypt, FDE solutions

Data in Transit

• Protects data moving across networks
• Protocols: TLS/SSL, IPSec, SSH, HTTPS

Data in Use

• Protects data while being processed
• Tools: Encrypted memory, HSMs

6. Cryptographic Attacks

• Birthday Attack – exploits hash collisions
• Replay Attack – retransmits captured data
• Man-in-the-Middle – intercepts and alters communications
• Known-plaintext / Ciphertext-only – targets algorithm weaknesses
• Downgrade Attack – forces use of weaker protocol
• Implementation Flaws – e.g., weak random number generators

Study Strategy

Tool	Action
Flashcards	Define terms and algorithm characteristics
Diagrams	Visualize asymmetric encryption and PKI flow
Practice Questions	Run 10–15 quiz questions per sub-topic
Summary Sheets	Create 1-page summary for each subsection

Exam Tips

• Watch for keywords: “shared key” = symmetric, “pair” = asymmetric
• Always consider purpose: encryption, hashing, signing
• PKI questions often test role of CA and OCSP
• Distinguish between data states: rest, transit, use