It's possible to use local storage or Aws s3, Azure, Google Cloud to store files.
When storing locally it makes all the documents 100% owned by you - but in some cases companies might want to bring a third party files storages to ensure the integrity of the documents.
But as was mentioned before in the comments - maybe bringing AWS QLDB as a third party to ensure the consistency of data with a local files storages is the best option. This way all documents can be logged with a third party so they can't be altered - while to content of the documents won't be shared with any third party.
But as was mentioned before in the comments - maybe bringing AWS QLDB as a third party to ensure the consistency of data with a local files storages is the best option. This way all documents can be logged with a third party so they can't be altered - while to content of the documents won't be shared with any third party.