Federation

Trust lists say whom to trust inside one country. So how is a professional licence issued in Bishkek recognised by a hospital in Istanbul? Or an identity credential issued in Europe checked at a hotel in Baku? The answer is federationAn arrangement where each country keeps ownership of its own list, but the lists can recognise each other..

Not one centre, but lists that recognise each other

There are two possible approaches. The first is to gather every institution into one central register. That looks easy, but no state wants to hand the register of its institutions to someone else. The second is federation: each country publishes and runs its own list, and the lists are recognised by pointing to each other. Tamga Network chose the second.

In practice: only Kazakhstan decides who goes on Kazakhstan's list. The network's job is to find that list, show it, and make sure the key that signs it really belongs to Kazakhstan.

How is an external list recognised?

Another operator's list appears in the list of lists with three pieces of information:

• Address: where the list is published.
• Pinned signer: the fingerprint of the key that signs it. A list signed with any other key is rejected.
• Scope: what that list is allowed to say, for example "only institutions issuing identity credentials" or "only wallet providers". Entries outside the scope are ignored.

Each entry rests on an approval: recognising a list is a written decision. An external list keeps its own freshness; if it goes stale, only the questions that depend on it become "cannot decide right now". The Türkiye list and the other lists are not affected.

Europe's lists are published in a common format defined by ETSI. Because Tamga can read that format, EU credential types such as the identity credential and the driving licence can also be verified once their scope is defined.

How does a hand-over work?

Today Tamga runs the Türkiye list provisionally, on behalf of the state. When the state, or a body it authorises, is ready to publish its own list, the list of lists points to the new address and the new signer. Institution certificates, credential types and credentials already issued stay the same; for wallets and verifiers only the address changes. The network was designed for this hand-over from the start.