AMHS Security and the PKI

The content of an AMHS message may optionally be protected by a digital signature. A digital signature ensures that the message content cannot be modified or corrupted without being detected, and that the recipient can be sure of the identity of the originator of the message. The technologies used to provide this protection are:

• A Public Key Cryptosystem (PKCS), used to generate and verify the digital signatures using digital 'certificates' allocated to each user that needs to create signed messages

• A Public Key Infrastructure (PKI), which is used to publish protected user's certificates. The PKI protects certificates from modification, corruption and substitution. It is intended that user's certificates are to be published through the ATN Directory.

In practice, the provision of security is some way off, simply because ANSPs need to implement opearational AMHS and the ATN Directory systems before implementing security techniques.

Confidentiality is not required within the international AMHS in support of the original AFTN traffic. However it might be required within an ANSP's own local applications and for newer non-AFTN applications of the AMHS.

The protection that digital signatures provide can only work with messages in the AMHS environment. As soon as a message leaves the AMHS (e.g. to flow through the AFTN), the digital signature must be deleted (because there is no equivalent protection provided by the AFTN). 

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