Finalize the project at Laravel

There is a script on JS to work with the signature CryptoPRO, it is necessary:

1.HTML make a page where we add JS code, on working with the plugin(Yes)
2. from this page we make an asynchronous request to the server to return the byte array of the pdf file in base64
3. Sign and upload the signature to the server
4. the server puts the signature and file in one archive and allows it to be downloaded to the client