Update PKCS#11 references in template wpa_supplicant.conf

Ditch the legacy syntax and manual engine mangling and just give an
example using simple PKCS#11 URIs that'll work with both GnuTLS and
OpenSSL.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

wpa_supplicant/wpa_supplicant.conf

@@ -168,10 +168,13 @@ ap_scan=1
 fast_reauth=1
 
 # OpenSSL Engine support
-# These options can be used to load OpenSSL engines.
+# These options can be used to load OpenSSL engines in special or legacy
+# modes.
 # The two engines that are supported currently are shown below:
 # They are both from the opensc project (http://www.opensc.org/)
-# By default no engines are loaded.
+# By default the PKCS#11 engine is loaded if the client_cert or
+# private_key option appear to be a PKCS#11 URI, and these options
+# should not need to be used explicitly.
 # make the opensc engine available
 #opensc_engine_path=/usr/lib/opensc/engine_opensc.so
 # make the pkcs11 engine available
@@ -480,6 +483,10 @@ fast_reauth=1
 #	(EAP-TLS). Full path to the file should be used since working
 #	directory may change when wpa_supplicant is run in the background.
 #
+#	Certificates from PKCS#11 tokens can be referenced by a PKCS#11 URI.
+#
+#	For example: private_key="pkcs11:manufacturer=piv_II;id=%01"
+#
 #	Alternatively, a named configuration blob can be used by setting
 #	this to blob://blob_name.
 #
@@ -490,6 +497,9 @@ fast_reauth=1
 #	used since working directory may change when wpa_supplicant is run
 #	in the background.
 #
+#	Keys in PKCS#11 tokens can be referenced by a PKCS#11 URI.
+#	For example: private_key="pkcs11:manufacturer=piv_II;id=%01"
+#
 #	Windows certificate store can be used by leaving client_cert out and
 #	configuring private_key in one of the following formats:
 #
@@ -1587,22 +1597,10 @@ network={
 	group=CCMP TKIP
 	identity="user@example.com"
 	ca_cert="/etc/cert/ca.pem"
-	client_cert="/etc/cert/user.pem"
-
-	engine=1
-
-	# The engine configured here must be available. Look at
-	# OpenSSL engine support in the global section.
-	# The key available through the engine must be the private key
-	# matching the client certificate configured above.
-
-	# use the opensc engine
-	#engine_id="opensc"
-	#key_id="45"
 
-	# use the pkcs11 engine
-	engine_id="pkcs11"
-	key_id="id_45"
+	# Certificate and/or key identified by PKCS#11 URI (RFC7512)
+	client_cert="pkcs11:manufacturer=piv_II;id=%01"
+	private_key="pkcs11:manufacturer=piv_II;id=%01"
 
 	# Optional PIN configuration; this can be left out and PIN will be
 	# asked through the control interface