> For the complete documentation index, see [llms.txt](https://docs.oklg.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.oklg.io/dapps/trusted-timestamping.md).

# Trusted Timestamping

### Direct Link

<https://app.oklg.io/#/timestamping>

### Smart Contract

<https://github.com/moontography/contracts/blob/master/contracts/OKLGTrustedTimestamping.sol>

### How many supported blockchains?

All OKLG-supported blockchains

### Cost of using service?

$2 USD per digital signature stored

### How to add a digital signature to the blockchain?

1. Once in the Trusted Timestamping dApp, you can simply click the **Add File to Calculate its Signature** button.\ <img src="/files/-MgNn4NBOkrp-3XjJfQO" alt="" data-size="original"><br>
2. The signature (or SHA256 hash of the file contents) will show in the UI. You can now click **Submit File Signature to Blockchain** to initiate the transaction.\ <img src="/files/-MgNnzqyfGF2n9c5g1FM" alt="" data-size="original"> <br>
3. You can now review all of your digital signatures you've stored in the table below. Note the signatures are tied to the address, so if/when you ever switch addresses your list will obviously reset. <img src="/files/-MgNoG7BezCeIsCGNGK0" alt="" data-size="original"> <br>