sftp doesn't connect to android (via sftpplug)

[zaffi]

When I try to connect total commander via sftpplug,
I get this error: "public key has wrong format, see readme.txt..."

but the server works fine:
+ i can connect to the same IP:port via putty, so the server is responsive
+ I can connect to other (linux) servers via total commader.

I have followed the readme's instructions.:
i have x.oub, and x.pem

I even tried via putty-agent. But even though the agent's terminal connects to the android phone, sftpplug couldn NOT connect via the agent/

What else can I check?

My system:
total commander 9.0b13
sftpplug: downloaded today
libcurl.dll etc - updated this week.
windows 7
puttygen 0.68

[ghisler(Author)]

How does the first line in the pem file look like? It needs to be
-----BEGIN RSA PRIVATE KEY-----
or
-----BEGIN DSA PRIVATE KEY-----

There is a newer format which begins with
-----BEGIN OPENSSH PRIVATE KEY-----

which isn't supported yet.

[zaffi]

this version of puttygen has 3 different options:

-----BEGIN OPENSSH PRIVATE KEY-----
-----BEGIN RSA PRIVATE KEY-----
(and the "ssh.com" that I didn't try)

I tried both RSA and also OPENSSH version, as *.pem files, but still got the same error.

BTW:
And the pub file (openssh pub key) starts with "ssh-rsa "
and ends with "== rsa-key-20170224"

P.S.
I know very little about encryption; but I never saw a client that asks for the public key - why "sftpplug" requires the public key?

[ghisler(Author)]

This one is the correct format:
-----BEGIN RSA PRIVATE KEY-----

And the public key: "ssh-rsa "

Make sure you enter the path to the private and public key correctly!