Upload Attachment in Base64-Asana API

Hi Asana Team,

I am trying to send my file in base64 format through Asana Attachment API but my file is getting corrupt after uploading.
My question is: Is there a form-data header I can use to tell Asana that the payload is base64 data? or any parameter to send in the request to tell Asana about the format?

I would really appreciate your help.
Thanks,
Ayushi