Windows CHMOD 600

I realize this is somewhat old but I just found the solution for myself in Windows 7. And it looks like this question went unresolved. I had all of the same errors including Cygwin missing cygintl-2.dll on chmod as you noted in the comments.

After extensive research and not finding any answers I ran:

C:\Users\mztriz\.ssh>ssh -v

OpenSSH_3.8.1p1, OpenSSL 0.9.7d 17 Mar 2004 usage: ssh [-1246AaCfghkNnqsTtVvXxY] [-b bind_address] [-c cipher_spec] [-D port] [-e escape_char] [-F configfile] [-i identity_file] [-L port:host:hostport] [-l login_name] [-m mac_spec] [-o option] [-p port] [-R port:host:hostport] [user@]hostname [command]

As you can see the version of OpenSSH I was running was quite outdated. However, I didn't know this because a quick google search of OpenSSH for Windows returns this old version.

After looking into the versioning I found OpenSSH for Windows 6.9p1-1 in the downloads section of that website.

This newer version of OpenSSH seems to fix all of the issues you mention.

I ran into the same problem on windows 10. I fixed it by doing the following steps.

1:- Right-click on the target file and select properties then select Security Tab

2:- Click Advanced and then make sure inheritance is disabled.

3:- Click apply and then click Edit in the security menu

4:- Remove all users except Admin user, which should have full control *Admin account should have all checkboxes checked on Allow column except special permission.

5:- Click Apply and then click OK.

You are good to go. This worked for Amazon EC2 .pem file and gave almost the same working as Chmod 600 on Linux.