Setting permissions for SFTP transfer (during transfer, not after)

[Ben Edwards]

When I SFTP a file onto a box I get the permissions -rw-r--r--, but I
want the permissions -rw-rw----. For security reasons I don't want to
transfer the file then change the permissions, I want the file to have
the permissions from when it first exists. To specify the requirement
a bit more formally:

"To enable a user to SFTP a files onto a box with the permissions set
to user and group readwrite and no access to world. These permissions
must be set at the beginning of the transfer (rather than after using
chmod). This is to ensure users can not read, change or delete the
file at any time (during or after the transfer)."

This can either be done as a SFTP set-up of something the user does
when transferring the files.
any Ideas?

Ben