The list of paths to trusted SSH key files controls the public / private key authentication that SFTP allows for.  This setting does not want you to enter in a 'trusted keys file', or a folder path, but rather the path to the actual key file itself.  So '/files/keys/' is bad, while '/files/keys/ben.pub' would be OK.  Separate multiple items with new lines.  Most SSH key formats are supported.

[attachments|ssh_keys.png]

There is also a more generic way to use this field.  If the key file has the exact name of the user logging in, you can instead reference the directory '/files/keys/'.  In this case there would need to be a file named 'ben' in that directory.

___OS X or Linux___
Generate a key pair by issuing this command in a Terminal window:

{{{ssh-keygen -t dsa}}}

Take the resulting public key and point CrushFTP to it as described above.

___Windows___

If you are unsure of how to generate a public / private key pair for your SFTP client, you may want to take a look at [puttygen|http://the.earth.li/~sgtatham/putty/latest/x86/puttygen.exe] for Windows to generate the keys.  CrushFTP can use the public key file you generate...do not put a password on it.