OpenSSH public keys not working with Cygwin

Question

I'm having trouble using OpenSSH for Windows using public key authentication. I've generated key pairs and transferred the keys to the remote server correctly but when I use ssh on windows it keeps prompting for a password. I transferred the same private key to my mac and was presented with an error that the permissions were too open (644) and would be ignored unless it was set to 600. "chmod 600 id_rsa" and boom, it worked. I can't seem to figure out a way to change this on windows via a script however and I'm unable to do so with the gui.

There must be a simple way to do this right? Is there a built in windows command for this? Im currently using XP but need this to also work on vista and 7.

Edit3: I scrapped the FAT32 support and downloaded a full cygwin install just to help diagnose the problem and used chmod 600 to set the permissions (which set the windows equivalent luckily). Still a failure. So I guess the issue isn't permissions but something else that is causing the the the keys to fail.

EDIT2: I managed to find a cacls command that might do what I need, but it will only work on NTFS file systems apparently and I need to support FAT32.

Edit1: When I run openSSH in 3x verbose mode, this is what I get:

OpenSSH_3.8.1p1, OpenSSL 0.9.7d 17 Mar 2004
debug2: ssh_connect: needpriv 0
debug1: Connecting to SERVER.NAME.HERE.CA [134.153.48.1] port 22.
debug1: Connection established.
debug1: identity file /home/jtg733/.ssh/identity type -1
debug3: Not a RSA1 key file /home/jtg733/.ssh/id_rsa.
debug2: key_type_from_name: unknown key type '-----BEGIN'
debug3: key_read: missing keytype
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug3: key_read: missing whitespace
debug2: key_type_from_name: unknown key type '-----END'
debug3: key_read: missing keytype
debug1: identity file /home/jtg733/.ssh/id_rsa type 1
debug1: identity file /home/jtg733/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1-hpn13v11lpk
debug1: match: OpenSSH_5.9p1-hpn13v11lpk pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_3.8.1p1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha1,diffie-hellman-  group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se,aes128-ctr,aes192-ctr,aes256-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour,aes192-cbc,aes256-cbc,aes128-ctr
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour,aes192-cbc,aes256-cbc,aes128-ctr
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: none,zlib@openssh.com
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: 
debug2: kex_parse_kexinit: first_kex_follows 0 
debug2: kex_parse_kexinit: reserved 0 
debug2: mac_init: found hmac-md5
debug1: kex: server->client aes128-cbc hmac-md5 none
debug2: mac_init: found hmac-md5
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug2: dh_gen_key: priv key bits set: 127/256
debug2: bits set: 534/1024
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug3: check_host_in_hostfile: filename /home/jtg733/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 2
debug3: check_host_in_hostfile: filename /home/jtg733/.ssh/known_hosts
debug3: check_host_in_hostfile: match line 3
debug1: Host 'SERVER.NAME.HERE.CA' is known and matches the RSA host key.
debug1: Found key in /home/jtg733/.ssh/known_hosts:2
debug2: bits set: 522/1024
debug1: ssh_rsa_verify: signature correct
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug2: key: /home/jtg733/.ssh/identity (0x0)
debug2: key: /home/jtg733/.ssh/id_rsa (0x100e9cb8)
debug2: key: /home/jtg733/.ssh/id_dsa (0x0)
debug1: Authentications that can continue: publickey,password,hostbased
debug3: start over, passed a different list publickey,password,hostbased
debug3: preferred publickey,keyboard-interactive,password
debug3: authmethod_lookup publickey
debug3: remaining preferred: keyboard-interactive,password
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Trying private key: /home/jtg733/.ssh/identity
debug3: no such identity: /home/jtg733/.ssh/identity
debug1: Offering public key: /home/jtg733/.ssh/id_rsa
debug3: send_pubkey_test
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,password,hostbased
debug1: Trying private key: /home/jtg733/.ssh/id_dsa
debug3: no such identity: /home/jtg733/.ssh/id_dsa
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password

So it appears to get the key, send the test packet and then jumps right into the next round of authentication.

Answer 1

For some reason generating the keys server side and then using scp to copy the server generated private key from the server onto the windows box and then using the cygwin chmod 600 worked like a charm.

I still have no idea why the server wouldn't accept the windows public key but windows would accept the server's private key. Seems like computer Voodoo to me.

Answer 2

You should be able to do it programmatically with the win32security API, but I don't know enough about ACL and Windows to give you a more complete answer.

You also should be able to right click the file, go to security, and set it there.

But you may have other issues at play on Windows - I haven't used OpenSSH enough to know.