> For the complete documentation index, see [llms.txt](https://docs.fetcch.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fetcch.xyz/pull-payments-layer/how-it-works/how-is-it-stored.md).

# How is it stored?

Let's delve into the storage and structure of transaction requests to understand how they're stored and verified:

**1. Structure of Transaction Request**

Transaction requests can reside in one of three states:

* **Fulfilled:** This state is achieved once a user has successfully paid a transaction request.
* **Pending:** This is the state when a transaction request is freshly created but hasn't been processed by the user.
* **Expired:** A transaction request transitions to this state when the current time surpasses its set expiration time.

**2. Storage Mechanism**

For ensuring security and traceability:

* Every version undergoes a `SHA-256` hashing process.
* If the second version of a transaction request is absent, a placeholder `null` SHA-256 hash (e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855) steps in.
* These hashes are then funneled into a merkle root generator function. The resulting merkle root is diligently stored on the target blockchain. This setup empowers users to authenticate whether their off-chain transaction requests are legitimate.

**3. Verification Process**

For payment platforms like wallets, there are a couple of options:

* **Trust Offchain Data:** Platforms can choose to rely on offchain data, but they should be fully aware of the associated risks.
* **Verify Offchain Data:** If platforms opt for verification:
  * They can solicit a proof from the offchain server.
  * Using the acquired proof, they can invoke the `verifyMerkleProof` function on their provider's contract.
  * By submitting the proof alongside the owner's address, they'll receive a straightforward `true` or `false` response, denoting the validity of the transaction request.

<figure><img src="/files/7tMGlC4CGMrNbUFpbXSw" alt=""><figcaption></figcaption></figure>

Note: Change transaction requests to pull payments

In essence, this framework ensures both the integrity and traceability of transaction requests, offering users and platforms a secure and transparent experience.


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