Encryption at Rest and in Transit

Overview

Encryption protects data confidentiality by transforming readable information into unreadable format using cryptographic keys. Modern systems implement encryption both at rest (stored data) and in transit (data being transmitted).

Encryption at Rest

Database Encryption

• Transparent Data Encryption (TDE): Automatic encryption/decryption
• Column-level encryption: Encrypt sensitive columns
• Application-level encryption: Encrypt before storing
• Full-disk encryption: Encrypt entire storage devices

File System Encryption

• Operating system level: BitLocker, FileVault, LUKS
• Cloud storage: AWS S3 encryption, Azure Storage encryption
• Key management: Separate keys from encrypted data

Encryption in Transit

TLS/SSL

• Transport Layer Security: Secure communication protocol
• Certificate-based: Public key infrastructure (PKI)
• Perfect Forward Secrecy: Session keys not compromised if long-term keys are
• Version considerations: Use TLS 1.2+ only

VPN and Network Security

• IPSec: Network layer encryption
• WireGuard: Modern VPN protocol
• Zero-trust networks: Encrypt all internal communication

Key Management

Key Lifecycle

• Generation: Secure random key creation
• Distribution: Safe key sharing
• Rotation: Regular key updates
• Revocation: Invalidate compromised keys
• Destruction: Secure key deletion

Key Management Systems (KMS)

• Hardware Security Modules (HSM): Tamper-resistant key storage
• Cloud KMS: AWS KMS, Azure Key Vault, Google Cloud KMS
• Key escrow: Recovery mechanisms for lost keys

Best Practices

1. Use Strong Encryption: AES-256, RSA-4096+
2. Separate Keys from Data: Never store keys with encrypted data
3. Regular Key Rotation: Automated rotation schedules
4. Monitor Access: Log all key usage
5. Defense in Depth: Multiple layers of encryption

Encryption is essential for protecting sensitive data in modern distributed systems.