What blockchain is (and isn’t)

The simplest definition: a shared, immutable ledger

Imagine an accounting ledger. Normally this ledger sits with one person who can alter the pages. On a blockchain, however, the same copy of the ledger lives on many computers (nodes), and once a record is written it cannot be changed retroactively.

Block and chain

Records are added not one by one but in groups (“blocks”). Each block contains the fingerprint (see hash) of the previous block. This chains the blocks together: if you try to alter a block, the fingerprints of every block after it break, and the tampering is exposed instantly.

Block 100

prevgenesis

data…

hash…a2

Block 101

prev…a2

data…

hash…c7

Block 102

prev…c7

data…

hash…e1

Consensus

So how do all these computers agree on what the next block will be? This is called a consensus mechanism. Bitcoin’s energy-intensive “Proof of Work” is the best known; but permissioned networks use far more efficient methods — for example the BFT (Byzantine Fault Tolerance) family, where specific, trusted nodes vote.

What is a permissioned network?

Unlike open networks anyone can join (Bitcoin, Ethereum), in a permissioned network it is clear who the validators are. The ledger Tamga plans is such a network: validators are not random people but trusted institutions and, in time, states.

Why is blockchain a “component, not the center” in Tamga?

This is crucial. Tamga Network is not a new blockchain network. Blockchain is only one part of Tamga and does a very limited job:

Written to the chain: only the non-personal data needed for trust — which institution is authorized to issue documents, institutions’ public keys, accreditation and revocation status.
NEVER written to the chain: your documents, your personal data, your diploma. These stay on your device (in your wallet).

Why is personal data not written to the chain?

Because a blockchain is immutable — but GDPR/KVKK grant you a “right to be forgotten.” Writing personal data to an immutable place conflicts with that right. Even an encrypted hash of the data is risky because it can be correlated. So the principle is clear: personal data never sits on the chain.

So as a user you never see the blockchain. Wallet, network fees, “gas,” tokens — you deal with none of it. You only use your digital identity; the blockchain works quietly in the background, only to make trust permanent.

Where Tamga stands today: signed trust lists first

A ledger only adds something when several independent parties run it. Run by one operator, it is just a slower database. So Tamga starts the way the EU itself does: with signed trust lists — versioned, hash-chained files that say which institutions may issue which documents, with their certificates and status. Every change is also written to a public anchor log.

Today (beta, pilot): signed trust lists + anchor log. No ledger.
Ledger (Besu, QBFT): only once at least two independent validator operators agree in writing. The list history is then replayed into the contracts and both are tested to give the same answers.
What does not change: institution and document-type identifiers are computed the same way in both, so no credential has to be reissued.