window.crypto.signText is a digital signature technology that has been available to Firefox users for 20 years. It is used by government and banking sites. It can be used to participate in plebiscites.
The window.crypto interfaces were removed from Firefox 35 and later releases. An add-on was developed as a stop-gap measure for users; that add-on is deprecated and does not work since Firefox 57, but still work with Seamonkey.
this fork based on the original signTextJS-0.7.7 add-on by mozkeeler