Can’t submit canvas html signature to database

We have a form written in Django and in this form there are fields where users can draw their signatures. We want to save the signatures drawn in these fields to the database and when we want to update them, we want them to come back in our form. I have to mentioned that before them we obey all the privacy and policy rules for users and they are aware of this In other words, our aim is to convert the signature drawn with canvas into a data that python can understand and save it,then we want to convert the data we saved back to canvas and make it appear on the html form. We would be glad if you can help with this.