If you want to use WinSCP as an SFTP client to connect to your Cloud Platform infrastructure, you must convert your SSH key into a format compatible with WinSCP. To convert your key into the required .ppk format, you can use PuTTYgen.

PuTTYgen is included in the WinSCP installation package.

To use PuTTYgen to convert a key into .ppk format:

1. Open PuTTYgen, go to Conversions, and then click Import key.

   PuTTYgen displays a window to load your key.

2. Browse to your SSH private key, select the file, and then click Open. Your SSH private key may be in the Users\[user_name]\.ssh directory.

3. Enter the passphrase associated with the private key, and then click OK. Note the key fingerprint confirms the number of bits is 4096.

4. Go to File, and then click Save private key to save the key in .ppk format.

You can now use the .ppk file as your key when you use WinSCP.

For more information, see the PuTTYgen documentation, including the note about key formats.