Disk Encryption

Disk Encryption for CEH: Complete Guide & Exam Tips

Why Disk Encryption is Important

Disk encryption is essential in cybersecurity because it protects data at rest from unauthorized access. If a device is lost, stolen, or improperly decommissioned, encrypted storage prevents attackers from accessing sensitive information. For organizations, disk encryption helps comply with regulations like GDPR, HIPAA, and PCI DSS that mandate data protection. In the context of ethical hacking, understanding disk encryption is crucial both for securing systems and identifying potential vulnerabilities.

What is Disk Encryption?

Disk encryption is a technology that converts data stored on a computer's storage media into an unreadable format that can only be deciphered with the correct authentication key. It can be applied to entire disk volumes (full-disk encryption), individual files, or containers that hold multiple files. Modern operating systems include built-in disk encryption tools like BitLocker (Windows), FileVault (macOS), and LUKS (Linux).

How Disk Encryption Works

1. Encryption Algorithms: Disk encryption typically uses symmetric encryption algorithms like AES (Advanced Encryption Standard) with key lengths of 128, 192, or 256 bits.

2. Authentication Methods: Users authenticate using passwords, PINs, hardware tokens, smart cards, or TPM (Trusted Platform Module) chips.

3. Encryption Process: When data is written to disk, it passes through the encryption engine, which uses the encryption key to transform it into ciphertext. When reading data, the process is reversed.

4. Key Management: Encryption keys can be stored in a TPM, on separate hardware tokens, or derived from user passwords. Key escrow systems allow organizations to recover data when users forget credentials.

5. Types of Disk Encryption:
- Full Disk Encryption (FDE): Encrypts everything on a drive including the OS
- File-Level Encryption: Encrypts individual files
- Volume Encryption: Encrypts specific partitions or logical volumes
- Container-Based Encryption: Creates encrypted containers for multiple files

Common Disk Encryption Tools

- BitLocker: Microsoft's encryption tool for Windows, supports TPM integration
- FileVault: Apple's encryption for macOS
- LUKS (Linux Unified Key Setup): Standard encryption for Linux systems
- VeraCrypt: Open-source, cross-platform disk encryption (successor to TrueCrypt)
- PGP: Can provide disk encryption along with its other cryptographic functions

Limitations of Disk Encryption

- Does not protect data in transit over networks
- Does not protect against attacks when the system is running and unlocked
- Can be vulnerable to cold boot attacks targeting RAM
- May be susceptible to evil maid attacks (physical tampering)
- Performance overhead on some systems

Exam Tips: Answering Questions on Disk Encryption

1. Know the algorithms: Memorize that AES is the most common algorithm for disk encryption, typically using 256-bit keys. Be familiar with other algorithms like Twofish and Serpent.

2. Understand attack vectors: Remember vulnerabilities specific to disk encryption:
- Cold boot attacks target encryption keys in RAM
- Evil maid attacks involve physical tampering
- Keyloggers can capture encryption passwords
- Backdoored firmware can compromise security

3. Differentiate protection states: Be clear on what disk encryption protects against (data access when powered off) and what it doesn't protect against (data in use while system is running).

4. Recognize implementation methods: Know the difference between hardware-based and software-based encryption solutions and their respective strengths.

5. Identify proper key management: Understand best practices for key storage, backup, and recovery methods.

6. Remember compliance requirements: Know which regulations require disk encryption and what they specify about implementation.

7. Watch for practical scenario questions: CEH exams often include scenario-based questions on selecting the appropriate encryption solution for specific needs.

8. Pay attention to terminology precision: The exam may try to confuse you with similar terms - know exactly what FDE, volume encryption, and file-level encryption refer to.

When answering multiple-choice questions about disk encryption, read all options carefully before selecting your answer, as there may be subtle technical differences that change the correctness of a statement.