Simultaneous Authentication of Equals (SAE)
--------------------------------------------

  SAE provides secure password-based authentication for 802.11.
This reference implementation is written with an OS-specific
component which manages the wireless interface and communicates
with the host OS, and an OS-independent component which implements
the SAE protocol.

  The OS-specific components reside in directories named for their
respective OS, for example the freebsd OS-specific component is 
in freebsd/meshd.c. The OS-independent component is sae.c. The 
other .c files are helper modules. See PORTING for a description
of the interfaces the modules have to each other.

  Multiple meshd applications can communicate over a loopback
interface to simulate a wireless mesh. Each OS-specific component
supports communication over the loopback interface.

  A monitor application, mon, can be used to sniff interfaces for
SAE traffic and provide pithy output.

RESTRICTIONS

  Currently, the only OS with wireless support is freebsd. The
linux module only supports communication over loopback. Extending
the linux OS-specific module-- linux/meshd.c-- to support wireless
interfaces is the subject of on-going work.

  Only elliptic curves defined over a prime field are supported--
i.e. no characteristic two curves and no prime modulus groups.
Therefore the only groups currently supported are 19, 20, 21, 25
and 26 from the IANA registry of RFC 2409's "Diffie-Hellman groups".

  meshd currently only supports Atheros radios.

REQUIREMENTS

  libcrypto from OpenSSL, version 0.9.8 or later. Basically, all
you need is EC support that has the pre-defined groups.

BUILDING

  The file freebsd_6.4_RC1_diffs contains patches for a few
kernel files in freebsd 6.4_RC1 (other versions should be
straightforward to patch as the diffs are minor) to allow for the
sending of 802.11 authentication frames via a BPF. Rebuild the
OS with these patchs.

  Edit the Makefile to point $(LIBS) to OpenSSL and make.

HOW TO CONFIGURE

  Configuration of sae and meshd are done with sae.conf and meshd.conf,
respectively, in the config directory. These files contain attribute and
value pairs in the form:
		attribute=value

One attribute supports a prioritized list of values in the form of a
value list:
		attribute=value1 value2 value3 ...

Lines beginning with '#' are treated as comments and ignored. 

  Attributes for sae.conf are:

	group: a prioritized list of groups to support. This is
		the only attribute that supports a value-list.
		There is no default.
	password: the password to use for authentication. There is
		no default.
	retrans: the amount of seconds to wait before retransmitting.
		Default is 3.
	thresh: the number of open connections allowed before
		anti-clogging tokens are demanded. Default is 5.
	blacklist: how long to ignore peers which fail authentication.
		Default is 30.
	debug: a bitmask to selectively enable/disable debugging.
		error debugging is bit 0x01, protocol messaging is bit
		0x02, state machine transitions are bit 0x04,
		crypto debugging is bit 0x08, and very verbose crypto
		debugging can be turned on with bit 0x10.
	lifetime: how long a negotiated PMK is valid for. At then end
		of this period the key will be deleted and the peer
		will be authenticated again (if it's still around).
	giveup: the number of errors and/or state-machine resyncronizations
		allowed before the conversation is abandoned. Default
		is 5.

  Attributes for meshd.conf are:

	interface: the name of the wireless interface to use.
		Default is "ath0".
	ssid: the ssid to beacon. Default is "meshd".
	passive: whether meshd will initiate (0) an SAE connection
		or wait (1) until initiated to. Default is 0.
	debug: when set to 1 sends more information to stdout.
		Default is 0.
	mediaopt: the media selection option for the wireless interface.
		Values are 0 for STA; 1 for ADHOC; 2 for HOSTAP; and,
		3 for MONITOR. Default is ADHOC.
	band: which radio band to use, "11a", "11b", or "11g". Default
		is 11b.
	channel: which channel to use in the defined band. Default
		is 6.

HOW TO USE

meshd MUST be run as root. After it's built just run it. If a beacon
advertising the configured ssid is received meshd will attempt SAE
authentication to the sender. If the sender is configured in a 
compatible fashion authentication will happen. When run over the 
loopback interface meshd will generate a random BSSID and begin
sending pseudo-beacons over the loopback interface. When another meshd
module connects to the loopback authentication will commense.

Note: a mediaopt of HOSTAP will prevent beacons from being received by
meshd. A mediaopt of STA will not result in beacons being sent out
the radio. It is possible to configure two mesh points to not see each
other or to ignore each other.

KNOWN ISSUES

This implementation is based version 8.01 of IEEE 802.11s. The specification
is pretty stable but it may change before final ratification.