Q: IS THERE A SIMPLE PROGRAM OR WEBSITE THAT WILL ALLOW ME TO COLLABORATE ENCRYPTED DOCUMENTS WITH OTHERS THAT ARE USING IPHONE OR ANDROID?

A: Sure. Google drive with google doc files. Encrypted in transit and at rest.

Original post: https://www.quora.com/Is-there-a-simple-program-or-website-that-will-allow-me-to-collaborate-encrypted-documents-with-others-that-are-using-iPhone-or-Android/answer/Marc-Mintz-4