We are considering a feature like this.

Here is a feature request for one more item -
Not just encryption of data while on the wire
But persistent encryption for the file being sent to remote host.
This would be ideal while storing files on remote cloud hosts.

In the WinSCP Login window left pane where you have Session, Environment, Connection, SSH and Preferences,
In this Encryption page/tab - there should be room for
Private key (for decrypting)
Public key (for encrypting)
Only one type of BEST encryption (AES, SHA, 3DES, Blowfish, etc) to avoid end user confusion,
and no choice to end user.

While establishing the session to the remote system,
if the public key is populated with the location of key file,
all the uploads files be encrypted with the public key.

While establishing the session to the remote system,
if the private key is populated with the location of key file,
all the downloads files be decrypted with the private key.

The directory structure and the files names be exactly same, on the remote system,
only the contents of the individual files be encrypted/decrypted during transfers.

--

If public key were to be shared with someone, they can only encrypt during upload.
Once uploaded, without private, they can download encrypted only files, good for nothing.

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