How to use smartcards with OpenSSH?

OpenSSH contains experimental support for authentication using
Cyberflex smartcards and TODOS card readers, in addition to the cards with
PKCS #15 structure supported by OpenSC. 

WARNING: Smartcard support is still in development. Keyfile formats, etc
are still subject to change.

To enable this you need to:

(1) install sectok or OpenSC

	Sources are instructions are available from
	http://www.citi.umich.edu/projects/smartcard/sectok.html

	or

	http://www.opensc.org/

(2) enable SMARTCARD support in OpenSSH:

	$ ./configure --with-sectok[=/path/to/libsectok] [options]

	or

	$ ./configure --with-opensc[=/path/to/opensc] [options]

(3) load the Java Cardlet to the Cyberflex card:

	$ sectok
	sectok> login -d
	sectok> jload /usr/libdata/ssh/Ssh.bin
	sectok> quit

(4) load a RSA key to the card:

	please don't use your production RSA keys, since
	with the current version of sectok/ssh-keygen
	the private key file is still readable

	$ ssh-keygen -f /path/to/rsakey -U 1
	(where 1 is the reader number, you can also try 0)

	In spite of the name, this does not generate a key.
	It just loads an already existing key on to the card.

(5) optional:

	Change the card password so that only you can
	read the private key:

	$ sectok
	sectok> login -d
	sectok> setpass
	sectok> quit

	This prevents reading the key but not use of the
	key by the card applet.

	Do not forget the passphrase.  There is no way to
	recover if you do.

	IMPORTANT WARNING: If you attempt to login with the
	wrong passphrase three times in a row, you will
	destroy your card.

(6) tell the ssh client to use the card reader:

	$ ssh -I 1 otherhost

(7) or tell the agent (don't forget to restart) to use the smartcard:

	$ ssh-add -s 1

-markus,
Tue Jul 17 23:54:51 CEST 2001