* Cisco purely password-based Lightweight
EAP(LEAP).
* Other vendors&Microsoft, use EAP and Transport Layer Security (EAP-TLS), which carries
out authentication through digital certificates.
If EAP-TLS is being used, the authentication
server and wireless device exchange digital certificates for
authentication purposes.
When
EAP-TLS is being used, the steps the server takes to authenticate to
the wireless device are basically the same as when an SSL connection is
being set up between a web server and web browser. Once the wireless
device receives and validates the server’s digital certificate, it
creates a master key, encrypts it with the server’s public key, and
sends it over to the authentication server. Now the wireless device and
authentication server have a master key, which they use to generate
individual symmetric session keys. Both entities use these session keys
for encryption and decryption purposes, and it is the use of these keys
that sets up a secure channel between the two devices.
* Protective EAP (PEAP), where only the server uses a digital
certificate.
If PEAP is being used instead, the user of the
wireless device sends the server a password and the server authenticates
to the wireless device with its digital certificate.
* EAP-TTLS provides
authentication that is as strong as EAP-TLS, but it does not require
user certificate. however require
server certificates.
User authentication is performed by
password, but the password credentials are transported in a securely
encrypted tunnel established based upon the server certificates.
* EAP-Tunneled TLS (EAP-TTLS) is an EAP
protocol that extends TLS.