Drone Encryption and Authentication

Introduction

Encryption and authentication protect drone communications from interception and manipulation.

Video Encryption

Analog vs Digital

Analog (5.8 GHz FPV) unencrypted. Digital (DJI, Walksnail) supports encryption.

DJI

OcuSync/Lightbridge use AES. Keys from binding. Early versions weak.

Digital FPV

• Walksnair: AES-128 optional
• DJI O3: mandatory
• HDZero: varies

Overhead

Encryption adds 10-50ms latency. Hardware acceleration helps.

Control Authentication

Binding

TX/RX establish shared secret. Button, QR, or phrase.

Challenge-Response

Random challenge, computed HMAC response. Prevents replay.

Session Keys

Binding keys derive session keys. Limits exposure.

MAVLink Signing

HMAC-SHA256, 13-byte signature. Timestamps prevent replay.

Firmware Security

Code Signing

Manufacturers sign firmware. Drones verify with public keys.

Secure Boot

Bootloader verifies signature. Chain of trust.

Rollback Prevention

Version numbers prevent downgrade to vulnerable versions.

Encrypted Firmware

Prevents reverse engineering. Keys in secure elements.

Key Management

Generation

CSRNG creates unpredictable keys. Hardware RNG preferred.

Storage

• Secure elements: ATECC608A
• TPM: hardware modules
• Encrypted flash

Rotation

Periodic updates limit exposure.

Revocation

CRLs or online status for compromised keys.

Protocols

PSK

Simple but vulnerable to extraction.

Diffie-Hellman

Secure key exchange. Ephemeral provides forward secrecy.

ECC

ECDH/ECDSA: smaller keys, same security.

Certificates

X.509 binds identity to key. Scalable PKI.

Threats

Eavesdropping

Encryption prevents disclosure.

MITM

Mutual auth prevents interception.

Replay

Sequence numbers, timestamps prevent.

Key Extraction

Secure elements mitigate.

Best Practices

• Use established libraries
• Constant-time operations
• Secure RNG
• Defense in depth

Conclusion

Encryption, authentication, firmware signing are fundamental. Proper key management essential.