I'm making a project work that encrypt and decrypt the email text using rsa, the rsa function to create an extension thunderbird add-ons. and almost finished, but I get the awkwardness when starting encryption, namely refernce error: new BigInteger is not deifned. hopefully the master javascript can help me, and I wrote this project javascirpt. thanks, and I'll keep waiting for your reply.

BigInteger is most likely a library you need to link to...

Additonally, consider encrypting on the server side rather than the client side.