# The Credential Attestation Process

A Decentralized Identity (DID) is the starting point for building reputation on the Toto Chain, but it's the **credentials** attached to that DID that give it meaning and trust. The process of formally linking a verified credential to a user's account on the blockchain is called **attestation**.

This document outlines the step-by-step process for credential attestation on the Toto Chain.

### The Participants

The attestation process involves two primary parties:

1. **The User (or Claimer):** The individual who wants to add a verifiable credential to their DID to build their reputation.
2. **The Attestation Provider (AP):** A trusted entity, approved by the Technical Committee, that is responsible for verifying the user's claim and recording it on the chain.

### The Attestation Flow: From Claim to On-Chain Record

The process involves both off-chain communication and a final on-chain transaction.

**Step 1: Off-Chain Verification**

The process begins off-chain, directly between the User and the Attestation Provider's service (e.g., their website or application).

1. **User Initiates a Claim:** The user navigates to an Attestation Provider's service and requests to have a credential verified. For example, they might want to prove they own a specific email address.
2. **Provider Verifies the Claim:** The Attestation Provider uses its own methods to verify the user's claim. For an email, this typically involves sending a confirmation link to that address, which the user must click.
3. **Provider Prepares the Attestation:** Once the claim is verified, the Attestation Provider's service prepares the necessary data for the on-chain transaction. This includes generating a hash of the claim's content (`claimHash`).

**Step 2: On-Chain Attestation**

After off-chain verification, the Attestation Provider submits a transaction to the Toto Chain to formally record the attestation. This is done by calling a specific function, or **extrinsic**, on the chain.

The primary extrinsic for this is `attestation.add()`.

This function takes several important parameters:

* **`claimHash`**: A cryptographic hash of the content of the user's credential. This allows the chain to store a unique reference to the claim without storing the private details of the claim itself (like the actual email address).
* **`ctypeHash`**: The hash of the Credential Type (cType) that defines the structure of this claim. This tells the chain what *kind* of credential is being attested (e.g., "Email," "Social Media," etc.).
* **`authorization`**: (Optional) This field can be used for more complex scenarios, but for a standard attestation, it is often left empty.
* **`account`**: The on-chain account ID (DID) of the **user** for whom the credential is being attested.

When the Attestation Provider calls this function, the chain performs a crucial check: **it verifies that the transaction is being sent from a trusted, official Attestation Provider account.**

If the sender is a recognized AP, the transaction succeeds. The chain then creates an official, on-chain record linking the `claimHash` to the user's `account`, and the user's reputation score is updated according to the `ctypeWeight` associated with that `ctypeHash`.

This process creates a secure and privacy-preserving system where verifiable credentials can be added to a user's digital identity, forming the building blocks of a robust, decentralized reputation.


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