# Attestation

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**Outdated Documentation:** This page covers the architecture used for USC V1, which was deprecated on 2026-03-30. For the latest documentation, please visit: [usc documentation](https://docs.creditcoin.org/usc)
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Attestation is the process by which the Creditcoin Decentralized Oracle keeps track of the finalized state of external source chains. State transitions of each source chain are monitored by a set of attestors. Each attestor submits an attestation, a cryptographic commitment showing their view of new blocks in the source chain. Since no single attestor can be fully trusted, we require consensus among independent attestors.

## **Attestation Process**

The attestation process is roughly outlined below:

* Attestors constantly monitor the *source chain* for new finalized blocks.
* Attestors then check the Creditcoin chain to see if they are eligible to attest at a given block height, using a mechanism such as a [*VRF*](https://en.wikipedia.org/wiki/Verifiable_random_function).
* If an attestor is eligible, it summarizes the progress of the source chain height from the last finalized attestation on Creditcoin to the current height (say *h*) based on their view. All eligible attestors for that block height sign their attestation and submit it to Creditcoin as their "vote" for the source chain at height *h*.
* Creditcoin validators verify the eligibility of votes received for a given block height. Each signed attestation from an attestor acts as a vote, and valid attestations with the same value (i.e., same digest) are accumulated. Once the accumulated votes for a particular attestation cross the required threshold, that attestation is confirmed and added to on-chain storage.

## Attestation Diagram

<figure><img src="/files/EQHrLO1pWWzPZzFt1X2e" alt=""><figcaption></figcaption></figure>


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