@vibhi, to comment about need to protect private information: note that Mattermost does not support end-to-end encryption for files nor messages. After verifying the identify of the server (via TLS), Mattermost assumes the user trusts the administrators running that server, as is often the case in workplace environments.
There’s some discussion about this feature request at https://mattermost.uservoice.com/forums/306457-general/suggestions/36662833-end-to-end-e2e-encryption-support.