This document, Part 1 – ACARS Message Security, which is the first part of a twopart specification, sets forth the provisions available to airlines and Datalink Service Providers (DSPs) to protect ACARS messages that are exchanged over traditional ACARS air-ground datalinks (VHF, HF, and SATCOM) and ground-ground communication networks. The provisions include specification of:

• Technical security controls (i.e., security mechanisms that are implemented primarily in hardware, software, and firmware), including encryption, message authentication, and data integrity algorithms.

• Message encoding, compression, and processing sequence for ACARS messages protected using AMS.

• Message format and content for ACARS messages protected using AMS.

• Protocol for exchanging ACARS messages protected using AMS.

Operational requirements for ACARS Message Security and specification of applications that may require ACARS Message Security are beyond the scope of this document. However, Part 2 of this specification provides important provisions and guidance for life cycle management of the cryptographic keys that are necessary for proper and secure operation of AMS.

Purpose of this Document

The purpose of this document is to provide an industry standard for ACARS Message Security (AMS), which permits ACARS datalink messages to be exchanged between aircraft and ground systems in a secure, authenticated manner using a uniform security framework. The security framework described herein is based on open international standards that are adapted to the ACARS datalink communications environment.