Thank you Martin!

Setting up OpenSSH, will give that a try and report back.

@Keith: PuTTYgen indeed does not support AES-256-CBC-encrypted keys. Probably because afaik that format is never used by OpenSSH.

But you might be able to use OpenSSH ssh-keygen to convert the key to a format that PuTTYgen understands.
Try:

---

It's actually suggested above already.

The private key file generated by Kiteworks (for SFTP/SSH connection) starts with

Using WinSCP 6.3.3 with PuTTYgen 0.81, we use PuTTYgen to try to load the private key file.
We get PuTTYgen error:

Couldn't load private key (unsupported cipher)

I had the same problem with my SFTP server (Solarwinds Serv-U) generating CFB keys that cannot being understood by PuTTYgen.
Please refer to this page:
https://web.archive.org/web/20221210015643/https://parkwharf.com/blog/cipher-feedback-encryption-woes-on-windows/

With a simple command you can convert from CFB to CBC:

Note: change dsa by rsa if your CFB key is using RSA

Converted successfully with PuTTYgen 0.73

Seem to have solved this. Under some *NIX system (Linux or, as in my case, FreeBSD) change directory to where the private key is. Lets say it is named private.key.
Run this:

It is basically for changing the password for the private key.
It asks now for the filename, enter: private.key
Then it asks for the current password, enter it
Then it asks for the new password twice, you can enter something new or just the same one.
It will re-write the file private.key but now it is coded with AES-128-CBC which PUTTY DOES understand! Now it can be imported by PuTTYgen.
This way I solved the problem with the key coded with DES-EDE3-CFB which nothing could understand except one non-freeware program!

@PLEP: Are you sure you do not confuse server's host key with your account private key? Account private keys should not be generated on server-side.

Anyway, PuTTYgen does not support this cipher indeed. You would need to re-encrypt the key using another tool before you will be able to import the key to PuTTYgen.

Hi

Cipher method when using 'Generate key pair' on Core FTP server side (not possible to change it)

Here is the header:

Thanks

@PLEP: What cipher does your key use?
Can you post the key header?

Hi Martin,

I'm using Core FTP and on the other side they are using WinSCP.
I tried to convert a SSH private key to a PuTTY using PuTTYgen.
I got a error message "Couldn't load private key (unsupported cipher)"

Need help. Thanks

will convert the OpenSSH key to one PuTTY understands.

Thanx :)

You need to convert your OpenSSH key to PuTTY format. Use PuTTYgen tool.
https://beta.winscp.net/eng/docs/ui_puttygen#other_formats

Edit 2022: WinSCP now can convert the key on its own, when you select OpenSSH key in session settings:
https://beta.winscp.net/eng/docs/ui_login_authentication#private_key

I can't connect using SSH2 private key :( But it works with Secure CRT & SecureFX programs. Did I do something wrong or WinSCP don't support this method?