Initially, the TL-location and TL-signing certificates are specified in the Official Gazette.

Later, following the decision of TDRA to modify the TL-location or the set of TL-signing certificates, TDRA might, as a machine-processable approach, publish these modifications in the UAE trusted list itself.

Such an instance of the trusted list is hereafter referred to as a ‘pivot TL’, as it represents a pivot point in the historical values of the TL-location and the TL-signing certificates. These pivot TLs form a chain of changes (changes of TL-location or TL-signing certificates) starting from the initial situation published in the Official Gazette up to the current one. These pivot TLs are archived for later reference.

To conclude on the current list of TL-signing certificates in order to validate the signature of the TL as explained above, one shall reconstruct that chain of pivot TLs. The following paragraphs explain how to reconstruct that chain.

From a technical perspective, the TL-location, TL-signing certificates, and the location of archived pivot TLs are included in the UAE trusted list such as:

• the <OtherTSLPointer> with AE <SchemeTerritory> contain the TL-location together with the PEM representation of the TL-signing certificates;
• the <SchemeInformationURI>, in reverse chronological order – that is, showing the most recent publication first – contains the list of:

• zero or more URLs where the archived preceding pivot TLs are published, back until and followed by
• the URL of the latest publication relevant to UAE trusted list in the Official Gazette.

In this respect, once the decision of TDRA to modify the TL-location or TL-signing certificates is reflected in a publication of a pivot TL, relying parties may detect these modifications in a machine processable way in the UAE trusted list, namely from changes of:

• the <OtherTSLPointer> with AE <SchemeTerritory>;
• the <SchemeInformationURI>.

When verifying the authenticity and integrity of the UAE trusted list, relying parties should, starting from the TL-location specified in the latest publication relevant to UAE trusted list in the Official Gazette, reconstruct the chain of pivot TLs to conclude on the current set of TL-signing certificates:

1. Based on the content of the UAE TL published at the TL-location, retrieve the

   location(s) of all pivot TLs present in <SchemeInformationURI>;

2. If no pivot TL is present, the current set of TL-signing certificates is the initial list in

   the above-mentioned publication of the Official Gazette

3. If pivot TLs are present: In the chronological order, for each pivot TL published at

pivot TL location(s), verify the authenticity and integrity of the list; using:

• for the first pivot TL, the set of initial TL-signing certificates specified in the above-mentioned publication of the Official Gazette; or
• for following pivot TLs, using the set of certificates specified in <OtherTSLPointer> with AE <SchemeTerritory> of the previous pivot TL in that ordered list;
• The final result is the current set of TL-signing certificates.

Transition period regarding the changes of TL-signing certificates or TL-location

After the publication of the pivot TL announcing changes in TL-signing certificates or TL-location, relying parties have 15 days (the duration of the transition period) to take these changes into account.

It is highly recommended to take these changes into account during the transition period rather than after it:

• During the transition period, this will have no impact on the ability to verify the authenticity and integrity of the UAE trusted list, as TDRA will take the relevant measures (e.g. not using the newly-announced [TL-signing] certificates during the transition period, or publishing the TL at both locations during the transition period)
• After the transition period, this may have an impact on the ability to verify the authenticity and integrity of the UAE trusted list, as TDRA may decide to:

• Sign/seal the UAE trusted list with one of the newly-announced TL-signing certificates.
• Remove the UAE trusted list from the previous TL-location.

Read more about The technical specifications and formats relating to the United Arab Emirates trusted list.