Security Information
Last updated: July 15, 2009
The test set can perform security procedures during the following call processing operations:
You can specify which security procedures are performed during these operations (
None
,
Auth & Int
, or
Auth Only
) using the
Security Operations
setting. Authentication and integrity protection are described in 3GPP TS 35.206, 24.008, 33.102, 25.331, and 35.202.
During authentication, both the UE and the network confirm that the other is valid by a series of computations based on a shared secret
Authentication Key
(K). The computations are performed using one of two
Authentication Algorithm
s, with K, SQN and the signalled values for
Random (RAND) Value
and
AMF Value
as inputs.
When integrity protection is enabled, the network encodes every RRC message with a digital signal (IK, which is derived from K, SQN, RAND and AMF). The UE rejects all RRC messages (except TC messages) that do not bear the proper digital signal.
Security Parameters
-
Security Operations
Security Operations
can be set to:
-
None
: No security procedures are performed during call processing operations.
-
Auth & Int
: Both authentication and integrity protection are performed during call processing operations.
-
Auth Only
: Only authentication is performed during call processing operations.
-
Auth, Int, & Ciph:
Authentication, Integrity Protection and Ciphering is performed during call processing operations.
GPIB command:
CALL:SECurity:OPERation
-
Authentication Algorithm
The test set supports both the normal operation authentication algorithm (
Milenage (Rijndael)
) and the conformance test algorithm described in 3GPP TS 34.108 (
Test 34.108
).
GPIB command:
CALL:SECurity:AUTHenticate:ALGorithm
-
Authentication Key
32 hex digits representing the 128-bit subscriber key (K). The default value of
Authentication Key
matches the Agilent USIM's "Applicative Key" as described at www.agilent.com/find/usim.
GPIB command:
CALL:SECurity:AUTHenticate[:KEY]
-
Operator Variant Parm Type
This setting specifies whether the
Operator Variant Auth Alg
contains the OP or OPc. If
Operator Variant Auth Alg
contains OP, the test set calculates OPc as per 3GPP TS 35.206.
GPIB command:
CALL:SECurity:AUTHenticate:OPVariant:PTYPe
-
Operator Variant Auth Alg
32 hex digits representing either the 128-bit OP or OPc. You must indicate, using the
Operator Variant Parm Type
setting, whether this setting contains OP or OPc.
GPIB command:
CALL:SECurity:AUTHenticate:OPVariant:PVALue
-
Random (RAND) Value
32 hex digits representing the 128-bit random challenge.
GPIB command:
CALL:SECurity:AUTHenticate:RANDom
-
AMF Value
4 hex digits representing the 16-bit authentication management field.
GPIB command:
CALL:SECurity:AUTHenticate:AMF
Reset Authentication SQN
The authentication sequence number (SQN) is set to zero each time the test set is powered on. It then increments each time an authentication procedure is performed. The SQN can be reset to zero by selecting
Reset Authen. SQN
or sending the
CALL:SECurity:AUTHenticate:SQN:RESet[:IMMediate]
command.
Security Results
During the authentication procedure (see
Security Ladder Diagrams
), the test set sends an Authentication Request message to the UE which contains RAND and AUTN (which is derived by the test set from K, SQN, AMF and RAND). If the UE determines that the AUTN contains a valid SQN and MAC, it sends an Authentication Response message to the test set, which includes RES. If the test set determines that the RES is valid, it returns an
Authentication Result: MM
or
Authentication Result: GMM
result (depending upon which domain has been authenticated) of
Success
. Otherwise, the test set sends the UE an Authentication Reject message and returns an
Authentication Result
of
Incorrect RES Length
or
RES Does Not Match
.
If the AUTN sent by the test set to the UE contains an invalid MAC or SQN, the UE sends an Authentication Failure message with the appropriate Cause information element (and AUTS if the failure cause is
Synch Failure
; the test set then initiates the re-synchronization procedure). The test set then reports this Cause value in both the
Authentication Result
(MM or GMM) and in the
UE Reported Failure Cause
result. For example, you can induce a
MAC Does Not Match
authentication failure as shown below by changing the
Authentication Key
setting in the test set to NOT match that in the UE's USIM (note that when using the
Test 34.108
Authentication Algorithm
, the mismatch must occur in the first 8 hex digits in order for authentication to fail).
Authentication Result
The authentication results reported by the test set include:
Authentication results are reported separately for the packet switched (PS) and circuit switched (CS) domains:
UE Reported Failure Cause
The
UE Reported Failure Cause
can be any number between 1 and 255. 3GPP TS 24.008 s10.5.3.6 and s10. 5.5.14 provide mappings of the numeric values to their equivalent causes. The causes relevant to authentication are shown below (see 3GPP TS 24.008 s4.3.2.5.1 and sG.3).
GPIB command:
CALL:MS:REPorted:AUTHenticate:FAILcause?
UE Reported Failure Cause
|
UE Reported Failure Cause
|
Description
|
|
|
20
|
MAC failure
|
"If the MS considers the MAC code (supplied by the core network in the AUTN parameter) to be invalid, it shall send an AUTHENTICATION FAILURE message to the network, with the reject cause 'MAC failure'."
|
|
21
|
Synch failure
|
"If the MS considers the SQN (supplied by the core network in the AUTN parameter) to be out of range, it shall send a AUTHENTICATION FAILURE message to the network, with the reject cause 'Synch failure' and a re-synchronization token AUTS provided by the USIM (see 3GPP TS 33.102 [5a])."
|
|
23
|
GSM authentication unacceptable
|
"In UMTS, an MS with a USIM inserted shall reject the authentication challenge if no Authentication Parameter AUTN IE was present in the AUTHENTICATION REQUEST message (i.e. a GSM authentication challenge has been received when the MS expects a UMTS authentication challenge). In such a case, the MS shall send the AUTHENTICATION FAILURE message to the network, with the reject cause "GSM authentication unacceptable"."
|