Implementing AES Encryption for Data at Rest

Overview

AES (Advanced Encryption Standard) is a symmetric block cipher standardized by NIST (FIPS 197) used to protect classified and sensitive data. This skill covers implementing AES-256 encryption in GCM mode for encrypting files and data stores at rest, including proper key derivation, IV/nonce management, and authenticated encryption.

When to Use

• When deploying or configuring implementing aes encryption for data at rest capabilities in your environment
• When establishing security controls aligned to compliance requirements
• When building or improving security architecture for this domain
• When conducting security assessments that require this implementation

Prerequisites

• Familiarity with cryptography concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

Objectives

• Implement AES-256-GCM encryption and decryption for files
• Derive encryption keys from passwords using PBKDF2 and Argon2
• Manage initialization vectors (IVs) and nonces securely
• Encrypt and decrypt entire directory trees
• Implement authenticated encryption to detect tampering
• Handle large files with streaming encryption

Key Concepts

AES Modes of Operation

Mode	Authentication	Parallelizable	Use Case
GCM	Yes (AEAD)	Yes	Network data, file encryption
CBC	No	Decrypt only	Legacy systems, disk encryption
CTR	No	Yes	Streaming encryption