Encryption: At Rest, In Transit, In Use

📋 At a Glance

Encryption protects data in three phases: At Rest (on disk/SSD), In Transit (on the network), In Use (during processing in RAM). For a self-hosted AI stack, the first two are mandatory, the third is a bonus for high-security scenarios.

The Three Encryption Layers

If you encrypt data on disk but send it unencrypted over the network, you have a gap. Encryption must cover all three states.

Three Encryption Layers: At Rest, In Transit, In Use

Data passes through three states — each needs its own protection.

Phase	What	Threat	Protection
At Rest	Data on disk/SSD	Hardware theft, filesystem access	LUKS, dm-crypt, Veracrypt
In Transit	Data on the network	Man-in-the-Middle, eavesdropping	TLS 1.3, WireGuard VPN, SSH Tunnel
In Use	Data in RAM during processing	Memory dumps, cold boot attacks	Confidential Computing, Intel SGX, AMD SEV

Encryption At Rest: Disk Encryption

At-rest encryption protects your data when someone physically accesses the disk — theft, disposal, repair. Without encryption, anyone can plug the drive into another machine and read everything.

LUKS (Linux Unified Key Setup)

LUKS is the standard for disk encryption on Linux. Most Linux distributions offer LUKS encryption during installation.

Encrypt an existing partition

# CAUTION: Create backup FIRST!

# Encrypt partition (all data will be erased!)
sudo cryptsetup luksFormat /dev/sdb1

# Open partition
sudo cryptsetup luksOpen /dev/sdb1 encrypted-data

# Create filesystem
sudo mkfs.ext4 /dev/mapper/encrypted-data

# Mount
sudo mount /dev/mapper/encrypted-data /mnt/secure-data

⚠️ Performance Impact

LUKS encryption on modern CPUs with AES-NI support has only about 1-3% performance overhead for sequential reads/writes. For random I/O (databases), overhead can be 5-10%. For AI workloads where the GPU is the bottleneck, you will not notice the difference.

What to Encrypt	Priority	Reason
Backup Volumes	MANDATORY	Backups contain everything — databases, configs, secrets
Database Volumes	HIGH	Customer data, credentials, AI training data
System Partition	MEDIUM	Protects configs and logs if stolen
Swap Partition	HIGH	RAM contents written to disk (secrets!)
Model Storage	LOW	Models are public, but your fine-tunes are not

Encryption In Transit: Network Encryption

Every connection between your services and to the internet must be encrypted. Even on your local network — networks get compromised, and ARP spoofing on a LAN is trivial.

Connection Type	Encryption	Configuration
Web Traffic (external)	TLS 1.3 (HTTPS)	Let's Encrypt or Cloudflare (automatic)
Remote Access	WireGuard VPN	Peer-to-peer, <1ms overhead, UDP-based
Server-to-Server	SSH Tunnel	ssh -L 5432:localhost:5432 user@db-server
Internal API Calls	mTLS or SSH Tunnel	Service mesh or manual tunnels
Docker Swarm Overlay	IPSec (automatic)	docker network create --opt encrypted

ℹ️ Encrypt Ollama API

Ollama listens on http://localhost:11434 by default — unencrypted. When other machines on the network access it, all prompt traffic flows in plaintext. Solution: reverse proxy with TLS in front, or SSH tunnel.

💡 WireGuard over OpenVPN

WireGuard is faster, simpler, and more secure than OpenVPN. The configuration fits in 10 lines. On Linux: sudo apt install wireguard. Netbird (netbird.io) offers a managed WireGuard solution for zero-trust networks.

Encryption In Use: RAM Protection

While an LLM processes your data, it sits unencrypted in RAM. An attacker with root access can read memory and extract prompts, responses, and model weights.

Technology	Availability	Protection	Overhead
Intel SGX	Xeon (server CPUs)	Enclaves in RAM	5-30%
AMD SEV-SNP	EPYC (server CPUs)	Encrypted VM memory	~2%
ARM CCA	ARMv9+	Realms (isolated regions)	Low
Software Solutions	Everywhere	Memory scrubbing, ASLR	Minimal

ℹ️ Irrelevant for most homelabs

Confidential Computing (Intel SGX, AMD SEV) is primarily relevant for cloud scenarios where you do not trust the hoster. In your own homelab, you control the hardware. The practical measures: encrypt swap (prevents plaintext RAM paging), enable screen lock (prevents physical access), and do not leave unnecessary root sessions open.

Encryption Checklist for Self-Hosted AI

Measure	Priority	Status Check
LUKS on backup volumes	MANDATORY	lsblk -o NAME,TYPE,FSTYPE \| grep crypt
Swap encrypted	MANDATORY	swapon --show + /etc/crypttab
TLS for all web services	MANDATORY	curl -vI https://your-service.local
SSH Key-Only (no password)	MANDATORY	grep PasswordAuth /etc/ssh/sshd_config
WireGuard for remote access	HIGH	wg show
Docker overlay encrypted	HIGH	docker network inspect --format '{{.Options}}'
Ollama behind reverse proxy	HIGH	curl -I https://ollama.local
Database connections TLS	MEDIUM	psql 'sslmode=require'

Encryption and GDPR

The GDPR requires "appropriate technical measures" to protect personal data (Art. 32). Encryption is explicitly mentioned as an example. Without encryption, you risk significantly higher penalties in case of a data breach.

⚠️ Encryption reduces notification obligation

GDPR Art. 34: If personal data was encrypted and the key was not compromised, the obligation to notify affected individuals in case of a data breach is waived. This is a strong incentive to deploy encryption everywhere.

💡 Learn more

More about data protection for AI applications in our GDPR Basics article and the GDPR Compliance Bundle.

Das Wichtigste

✓Three encryption phases: At Rest (disk), In Transit (network), In Use (RAM). The first two are mandatory.
✓LUKS for disks, TLS 1.3 for web traffic, WireGuard for remote access. All standard tools, no specialist knowledge needed.
✓Encrypt the swap partition! Otherwise RAM contents (prompts, API keys) end up in plaintext on disk.
✓GDPR Art. 32 explicitly mentions encryption. Encrypted data reduces notification obligations for breaches (Art. 34).
✓Ollama API runs unencrypted — put a reverse proxy with TLS or SSH tunnel in front.

Sources

LUKS / cryptsetup — Linux Disk Encryption Standard
WireGuard — Modern VPN Protocol
GDPR Art. 32, 34 — Security of processing, notification of data breaches
Confidential Computing Consortium — Encryption In Use Standards