As mentioned in the Intro to Cygwin page, Cygwin is able to give POSIX binaries the ability to authenticate to the Windows SID subsystem.

To take advantage of this feature for:

SSH authenticationEdit

Install the OpenSSH daemon according to SSHD

Be sure to set the CYGWIN variable for the daemon to 'ntsec'

Windows usernames with spacesEdit

According to the Cygwin FAQ , these usernames will cause problems for Cygwin. Avoid using them.

From the official Cygwin documentationEdit

Using Windows security in Cygwin