> Is there a way, to create an additional user (under my account) that will be limited to performing specific actions (like only file upload, without the option to delete or download anything)?
All data that lftp send to SFTP/FTPS are encrypted.
You can use a command like this to start lftp:
lftp -u your_username -e 'set ftp:passive-mode on;' ftps://ftp.storagemadeeasy.com lftp will ask you to enter the password. When you will typing the password then it will be hidden.