uard against interception or alteration of user or control plane data. The fact that almost all the user data is already encrypted at a higher layer or by the application does not change the political and reputa- tional cost of suffering a breach. Similarly, regulators in some countries are mandating encryption of segments of the transport network to safeguard the data integrity of subscribers. 11.5.1 PTP Security The current versions of the ITU-T telecom profiles have not adopted any of the security mechan- isms from the IEEE 1588-2008 version of the PTP standard. With the publication of the new secur- ity Annex P in the 1588-2019 release, one would expect that some security features will be incor- porated into future revisions of the telecom profiles. For that reason, some of the basic elements of implementing a more secure version of the transportation of timing are outlined in the following section, "Integrity Verification from IEEE 1588-2019." In the new edition of the 1588 standard, a multipronged approach to security has been developed and is described in the informative Annex P. All the prongs are optional for PTP and not required in a standard implementation (and are not yet adopted by the telecom profiles). Several prongs can be applied in parallel; they are not mutually exclusive. The four "prongs" of the approach in Annex P are as follows: Prong A: Authentication and integrity verification Prong B: The use of transport security Prong C: Architectural guidance Prong D: Monitoring and management mechanisms The following sections expand on these concepts and examine how they can be applied to future de- ployments. The focus is on one item: the encryption of the transport links with MACsec. Prong A: Authentication Field and Security Processing This prong includes methods to enhance the security of the timing signal using a field to carry a checksum that is used by the receiver: Section 16.14 of IEEE 1588-2019 describes a type, length, value field (TLV) that can be appen- ded to messages. This TLV includes