Description
Title of Invention: SECURITY FOR PROSE GROUP COMMU¬
NICATION
Technical Field
[0001] This invention is related to a secure system and a method of performing authen
tication and authorization, more specifically, to a method of performing the authen
tication and the authorization in Proximity based Service (ProSe) communication.
Background Art
[0002] 3GPP (3rd Generation Partnership Project) has started to study Proximity based
Services (ProSe) for both commercial and public safety uses. 3GPP SA1 (Services
Working Group) has initiated some security requirements for secure communication,
UE (User Equipment) identity, and privacy protection.
[0003] ProSe represents a recent and enormous socio-technological trend. The principle of
these applications is to discover instances of the applications running in devices that
are within proximity of each other, and ultimately to also exchange application-related
data. In parallel to this, there is interest in proximity-based discovery and commu
nications in the public safety community.
[0004] ProSe communication can provide services to the UEs in proximity via an eNB
(Evolved Node B) or without the eNB. The SA1 requires that the ProSe service be
provided to UEs with or without network coverage. The UEs can discover other nearby
UEs or be discovered by other UEs, and they can communicate with each other. Some
use cases can be found in NPL 1.
Citation List
Non Patent Literature
[0005] NPL 1: 3GPP TR 22.803 Feasibility study for Proximity Services (ProSe), (Release
12)
Summary of Invention
Technical Problem
[0006] However, despite the security issues involving authentication and authorization for
direct communication as well as privacy issues, 3GPP SA3 offers no security solution.
Solution to Problem
[0007] The present invention has been made to present an overall security solution for the
above-mentioned security issues.
[0008] In one embodiment, there is provided a method of performing authentication and au
thorization in Proximity based Service (ProSe) communication by a requesting device
which sends a request of a communication and a receiving device which receives the
request from the requesting device, the method including deriving session keys Kpc
and Kpi from an unique key Kp at the requesting and receiving devices, using the
session keys Kpc and Kpi for ProSe communication setup and direct communication
between the requesting and receiving devices, starting the direct communication with
the requesting and receiving devices. The key Kpc is confidentiality key and the key
Kpi is integrity protection key.
[0009] In another embodiment, there is provided a secure system including a plurality of
User Equipments (UEs), and a Proximity based Service (ProSe) server, including a r e
questing device which sends a request of a communication, and a receiving device
which receives the request from the requesting device. The requesting and receiving
devices derive session keys Kpc and Kpi from an unique key Kp. The requesting and
receiving devices use the session keys Kpc and Kpi for ProSe communication setup
and direct communication between the requesting and receiving devices. The r e
questing and receiving devices start the direct communication with the requesting and
receiving devices. The key Kpc is confidentiality key and the key Kpi is integrity
protection key.
Advantageous Effects of Invention
[0010] A secure system and a method of making a secure communication can present an
overall security solution for security issues.
Brief Description of Drawings
[001 1] The above and other objects, advantages and features of the present invention will be
more apparent from the following description of certain preferred embodiments taken
in conjunction with the accompanying drawings, in which:
[fig.lA]Fig. 1A is a schematic view showing the ProSe Communication scenario in
NPL 1;
[fig.lB]Fig. IB is a schematic view showing the ProSe Communication scenario in
NPL 1;
[fig.2]Fig. 2 is a schematic view showing an example of the systems which provide a
method of making a secure communication according to an exemplary embodiment of
the present invention;
[fig.3]Fig. 3 is a schematic view showing a secure system of an exemplary em
bodiment of the present invention;
[fig.4]Fig. 4 is a sequence diagram explaining a method of making a secure commu
nication of an exemplary embodiment of the invention;
[fig.5A]Fig. 5A is a schematic view showing a One-to-one session;
[fig.5B]Fig. 5B is a schematic view showing a One-to-many session; and
[fig.5C]Fig. 5C is a schematic view showing a Many-to-many session.
[fig.6]Fig. 6 is a sequence diagram showing One-to-one communication of an
exemplary embodiment of the present invention;
[fig.7]Fig. 7 is a sequence diagram showing the option 1 of One-to-many commu
nication of an exemplary embodiment of the present invention;
[fig.8]Fig. 8 is a sequence diagram showing the option 2 of One-to-many commu
nication of an exemplary embodiment of the present invention; and
[fig.9]Fig. 9 is a sequence diagram showing Many-to-many communication of an
exemplary embodiment of the present invention.
Description of Embodiments
[0012] For purposes of the description hereinafter, the terms "upper", "lower", "right", "left",
"vertical", "horizontal", "top", "bottom", "lateral", "longitudinal", and derivatives
thereof shall relate to the invention as it is oriented in the drawing figures. However, it
is to be understood that the invention may assume alternative variations and step
sequences, except where expressly specified to the contrary. It is also to be understood
that the specific devices and processes illustrated in the attached drawings, and
described in the following specification, are simply exemplary embodiments of the
invention. Hence, specific dimensions and other physical characteristics related to
exemplary embodiments disclosed herein are not to be considered as limiting.
[0013] In the exemplary embodiments, though the security solutions with a focus on
specifically direct communication, discovery, and communication will be explained,
the solutions can be applied to other communications as well.
[0014] Firstly, definitions given in 3GPP TR 21.905: "Vocabulary for 3GPP Specifications"
will be explained.
[0015] ProSe Direct Communication:
A communication between two or more UEs in proximity that are ProSe-enabled, by
means of user plane transmission using E-UTRA technology via a path not traversing
any network node.
[0016] ProSe-enabled UE:
A UE that supports ProSe requirements and associated procedures. Unless explicitly
stated otherwise, a Prose-enabled UE refers both to a non-public safety UE and a
public safety UE.
[0017] ProSe-enabled Public Safety UE:
A ProSe-enabled UE that also supports ProSe procedures and capabilities specific to
Public Safety.
[0018] ProSe-enabled non-public safety UE:
A UE that supports ProSe procedures but not capabilities specific to public safety.
[0019] ProSe Direct Discovery:
A procedure employed by a ProSe-enabled UE to discover other ProSe-enabled UEs
in its vicinity by using only the capabilities of the two UEs with rel.12 E-UTRA
technology.
[0020] EPC-level ProSe Discovery:
A process by which the EPC determines the proximity of two ProSe-enabled UEs
and informs them of their proximity.
[0021] Figs. 1A and IB are schematic views showing the ProSe Communication scenarios
in NPL 1. When a UE 11 and a UE 12 which are involved in the ProSe Commu
nication are served by the same eNB 19 and network coverage is available, a system
100a can decide to perform ProSe Communication using control information
exchanged between the UEs 11, 12, eNB 19 and an EPC (Evolved Packet Core) 14
(e.g., session management, authorization, security) as shown by the solid arrows in Fig.
1A. For charging, modifications should be minimized with respect to the existing ar
chitecture. The UEs 11 and 12 can in addition exchange control signaling via the ProSe
Communication path as shown by the dashed arrow in Fig. 1A.
[0022] When the UEs 11 and 12 involved in the ProSe Communication are served by
different eNBs 19, 20 and network coverage is available, a system 100b can decide to
perform ProSe Communication using control information exchanged between the UEs
11, 12, eNB 19 and the EPC 14 (e.g., session management, authorization, security) as
shown by the solid arrows in Fig. IB. In this configuration, the eNBs 11 and 12 may
coordinate with each other through the EPC 14 or communicate directly for radio
resource management as shown by the dashed arrow between the eNBs 11 and 12 in
Fig. IB. For charging, signaling modifications should be minimized with respect to the
existing architecture. The UEs 1 1 and 12 can in addition exchange control signaling
via the ProSe Communication path as shown by the dashed arrow between the UE 11
and the UE 12 in Fig. IB.
[0023] If network coverage is available for a subset of the UEs, one or more Public Safety
UEs may relay the radio resource management control information for other UEs that
do not have network coverage.
[0024] If network coverage is not available, the control path can exist directly between
Public Safety UEs. In this configuration, the Public Safety UEs can rely on preconfigured
radio resources to establish and maintain the ProSe Communication. Alter
natively, a Public Safety Radio Resource Management Function, which can reside in a
Public Safety UE, can manage the allocation of radio resources for Public Safety ProSe
Communication.
[0025] Fig. 2 is a schematic view showing an example of the systems which provide a
method of making a secure communication according to an exemplary embodiment of
the present invention. As shown in Fig. 2, a system 10 includes the UE 11, the UE 12,
an E-UTERN 13, the EPC 14, a ProSe Function 15, a ProSe APP Server 16, a ProSe
APP 17, and a ProSe APP 18.
[0026] The UE 11 and the UE 12 can communicate through a PC5, the UE 11 and the EUTERN
13 communicate through LTE-Uul, and the UE 12 can communicate with the
E-UTERN 13 and the ProSe Function 15 through LTE-Uu2 and a PC3, respectively.
The EPC 14 and the ProSe Function 15 can communicate through a PC4, the ProSe
APP server 16 can communicate with the EPC 14 and the ProSe APP 18 through a
SGI and a PCI, respectively, and the ProSe Function 15 can communicate by itself
through a PC6.
[0027] As described above, existing keys can be used when using an infrastructure, i.e., via
eNodeB. However, a new solution is needed for device-to-device direct discovery and
communication; for example, a key can be sent from the network to communicating
parties, a key can be created between communicating parties, or a similar algorithm for
negotiation can be used directly or via the network. Further, a new solution is also
needed for the security over the unlicensed spectrum.
[0028] Two different modes for ProSe Direct Communication one-to-one are supported:
Network independent direct communication: This mode of operation for ProSe
Direct Communication does not require any network assistance to authorize the
connection and communication is performed by using only functionality and in
formation local to the UE. This mode is applicable only to pre- authorized ProSeenabled
Public Safety UEs, regardless of whether the UEs are served by E-UTRAN or
not.
[0029] Network authorized direct communication: This mode of operation for ProSe Direct
Communication always requires network assistance and may also be applicable when
only one UE is "served by E-UTRAN" for Public safety UEs. For non-Public Safety
UEs both UEs must be "served by E-UTRAN".
[0030] PCI:
It is the reference point between the ProSe application 18 in the UE 12 and in the
ProSe App Server 16. It is used to define application level requirements.
[0031] PC2:
It is the reference point between the ProSe App Server 16 and the ProSe Function 15.
It is used to define the interaction between the ProSe App Server 16 and ProSe func
tionality provided by the 3GPP EPS via the ProSe Function 15. One example of use of
it may be for application data updates for a ProSe database in the ProSe Function 15.
Another example of use of it may be data for use by the ProSe App Server 16 in interworking
between 3GPP functionality and application data, e.g. name translation.
[0032] PC3:
It is the reference point between the UE 12 and the ProSe Function 15. It is used to
define the interaction between the UE 12 and the ProSe Function 15. An example of
use of it is for configuration for ProSe discovery and communication.
[0033] PC4:
It is the reference point between the EPC 14 and the ProSe Function 15. It is used to
define the interaction between the EPC 14 and the ProSe Function 15. Possible use
cases of it may be when setting up a one-to-one communication path between UEs or
when validating ProSe services (authorization) for session management or mobility
management in real time.
[0034] PC5:
It is the reference point between the UE 11 to the UE 12 used for control and user
plane for discovery and communication, for relay and one-to-one communication
(between UEs directly and between UEs over LTE-Uu).
[0035] PC6:
This reference point may be used for functions such as ProSe Discovery between
users which are subscribed to different PLMNs.
[0036] SGi:
In addition to the relevant functions defined in TS 29.061 [10] via SGi, it may be
used for application data and application level control information exchange.
[0037] Fig. 3 is a schematic view showing a secure system of an exemplary embodiment of
the present invention. As shown in Fig. 3, a secure system 1 of an exemplary em
bodiment of the present invention includes one or more requesting UEs LOl, an
operator network L02, and one or more receiving UEs L03. A method of performing a
secure communication includes steps of a secure group management LI, a secure
discovery L2, an initial authorization L3, an authentication L4, an authorization L5, a
security association establishment L6, a secure communication L7, and a termination
L8, which are performed between UEs (the requesting UE LOl, the receiving UE L03)
with or without interacting with the operator network L02.
[0038] Assuming that the network coverage is available for UEs, broadcasting is presented
as an example in this exemplary embodiment, but this exemplary embodiment also
applies to multiple-casting and one-to-one communications as shown in Figs. 1A, IB,
and 2.
[0039] From setting up of a group till communication termination, security is needed in each
step as described below. Note that steps LI - L 4 can be in a different order depending
on the service or application.
[0040] LI: Secure group management
Members can join securely, members can leave securely, and an authorization level
of service and each of the members, and any other required information can be
modified securely.
[0041] L2: Secure discovery should happen
If discovery is not secured, a device may start communication with a wrong party or
a rogue device, with the result that masquerading attacks can happen that in turn could
lead to fraudulent charging. For this purpose, the discovery related communication
must be secured, i.e., a UE authenticates identity of other UEs in proximity; integrity
protection for discovery and a device should be able to authenticate the message.
[0042] L3: Initial Authorization
The initial authorization based on secure discovery will lead to the decision that the
discovered device belongs to the group, and thus the next step can start.
[0043] L4: Authentication
Once the device is discovered and authorized as a part of the group, there should be a
mutual authentication; otherwise there is still a scope of attacks.
[0044] L5: Authorization
The next level of authorization will find out what services can be used between the
devices which belong to the same group. For example, a UE is allowed to send and
receive different types of messages or is only allowed to receive broadcasting
messages.
[0045] L6: Security association establishment (Key derivation and management)
The UEs which belong to the same group should have keys to protect their commu
nication such that other UEs which do not belong to the group or an attacker cannot
eavesdrop or alter the messages.
[0046] L7: Secure communication
The communication between UEs in the same group can be protected by the security
association, with integrity and/or confidentiality protection according to the sub
scription service type.
[0047] L8: Termination
The secure termination can provide security when UE(s) suspend or terminate the
communication, or when the entire group communication is terminated.
[0048] The detailed method of performing a secure communication of an exemplary em
bodiment of the invention that fulfills the security requirements will be explained in
the following sections. Fig. 4 is a sequence diagram explaining a method of making a
secure communication between UE 100 and network 200 of an exemplary embodiment
of the invention.
[0049] [1] Group setting and management (LI)
A group can be
(1) two devices communicating with each other (one-to-one), or
(2) more than two devices (one-to-many) where one UE can communicate with the
other devices.
(3) more than two devices (many-to-many) that can communicate with each other.
[0050] A group can be set up for different communication purposes, and group members can
be changed. To form a group, the operator network L02 can check the requesting UE
LOl which requests the UE L03 which it wants to communicate with, verify devices if
they can communicate with each other, and inform the verified devices at both sides
(the requesting UE LOl and the receiving UE L03) of the request and formation.
[0051] Hereinafter one example of creating a group will be explained. As shown in Fig. 4, a
UE 100 requests ProSe subscription to a network 200 and creates a group (Step 1). In
step 1, the UE 100 needs to meet conditions, that is policy, e.g. interest, specific
location etc. Also the network 200 needs to verify whether UE meets conditions, that is
policy, e.g. proximity range, subscription, home network in case of roaming UE, WiFi
or not, ProSe enabled, etc. The group is strictly formed, for example, the members of
the group should be registered in a whitelist, or the group is dynamically formed on a
request from the UE 100, or by the network 200 if the network 200 knows all UE
conditions.
[0052] For creating a secure group, UEs 100 must agree to be a part of the group, and only
"agreed" UEs 100 become group members. A group management includes adding
group members, removing group members, ending the group, and adding temporary
group members. Each UE 100 can see who is in proximity from e.g. a social network
application, and requests for ProSe service, and the ProSe server needs to perform the
authorization, but does not have to perform discovery.
[0053] [2] Discovery - Secure detection of UEs in proximity (L2)
Discovery and group creation in [1] can happen at the same time or be independent
procedure.
There can be following three means that a UE (the requesting UE LOl) can discover
other UEs (the receiving UEs L03) in proximity: (1) Broadcast based, (2) Network
based, and (3) Device service level information based. How secure discovery can be
done will be described as follows.
[0054] [2-1] Broadcast based solution
There are six ways (si - s6) in Broadcast based solution:
[0055] (si) Token
The broadcast message can contain a token that only the given UEs can have. The
token should be used only once to prevent the receiving side from reusing it. In order
to reach that, the UEs can calculate a token each time on receiving the broadcast
message, or the network can inform all the UEs of the token to be used next. This can
be used for such a use case as an information notification kind of service, since the
token can be reused by the receiving side.
[0056] (s2) Signing message
The broadcast message can be signed by a key that can be verified either by the
receiving UEs or by the network for the receiving UEs. Signing can happen by
different key management solutions or it can happen using the current keys for com
municating with the infrastructure network (or derivation from current keys) - a new
key hierarchy might be needed here.
[0057] (s3) Message ID
The broadcast message can have an ID that can be verified during the authentication
and is used initially only for authorization.
[0058] (s4) Random value
The broadcast message can contain a random value that can only be generated by the
network and UE. Verification of the random value is done by the network on behalf of
communicating UEs.
[0059] (s5) Key
Each UE has a specific key belonging to other devices, and thus it sends a potentially
long broadcast or a new type of broadcast that is sent in pieces with encrypted /
integrity protected parts for each UE in the group.
[0060] (s6) Stamp
The broadcast message can be signed with time-stamp and life-time. Note that this
life-time can be a very short period or can last until the next broadcast.
[006 1] [2-2] Network based solution
A network can provide information. For this purpose, the network can use the
location information received from the UE (the requesting UE L01), and the location
information can be protected by the existing network security mechanism.
[0062] [2-3] Device service level information based solution
The requesting UE L01 can use location information provided by a social network or
other services. Security can be ensured in an application layer.
[0063] Detailed examples of the discovery will be explained. The UE 100 can set features
and/or capabilities of Discovery /Discoverable in D2D (device-to-device commu
nication) server.
Case 1A:
If the UE 100 does not know whether the other UEs are in proximity, the UE 100 can
request the ProSe server for the ProSe service, and the ProSe server can send out the
request for the ProSe service and meanwhile get the other UEs location information.
Case 2A:
If the UE 100 can see who is in proximity from e.g. a social network application, and
asks for service, the ProSe server needs to perform the authorization but does not have
to perform Discovery.
[0064] If the ProSe server performs the authorization, the UEs 100 enable the ProSe and/or
UEs 100 to be allowed to get given service/communication means.
[0065] If the discovery is done based on the proximity of UEs 100, the UE 100 sends
location information periodically protected by a unicast security context. The network
200 requests location information when needed or periodically. The request (step 3)
can be broadcasted, and the broadcasted message requires security. The response (step
4) can be protected by the unicast security context.
[0066] The Network stores the conditions for proximity, which can also be given by the re
questing and receiving UE. The network 200 can broadcast to the receiving UEs in a
neighborhood which are allowed to be discovered, and the UEs respond with protected
messages. The UE 100 informs the network 200 of its conditions and capabilities at a
first communication and/or registration or when any change happens.
[0067] The broadcast based solutions by the network 200 or the UE 100 require one or more
of the following requirements. That is, the receiving side should be able to verify the
source, the broadcast message should not be re-used, the network 200 which receives
the response should be able to verify it, or the response should be discarded if it is too
long. The UE 100 can use one or more of solutions for performing secure discovery.
The solutions include a token, a sign, a message, a message ID, a random value, keys,
and stamps. Note that those solutions can be used in the step 5 (mutually authenticate,
the authentication L4), in the step 6 (authorize, the authorization L5), and in the step 7
(generate keys and negotiate algorithm, the secure communication L7), as shown in
Fig. 4. The steps 5 to 7 can happen together, and might be related to broadcast security.
[0068] [3] Initial Authorization (L3)
The initial authorization varies according to the above discovery solution.
[0069] [3-1] Broadcast based:
Whether the requesting UE L01 is allowed to communicate with the receiving UE
L03 can be checked by a network or by the receiving UE L03 having a proof provided
by the network.
[0070] [3-2] Network based:
The requesting UE L01 and the receiving UE L03 can perform a mutual authen
tication over the direct wireless interface.
[0071] [3-3] Device service level information based:
The receiving UE L03 checks a list maintained by the user or in a UE among the
members of the group of devices for ProSe service purpose.
[0072] [4] Authentication (L4)
Once the requesting UE L01 is identified as belonging to the same group, then au
thentication takes place. Authentication can be carried out locally or by interacting
with the network.
[0073] [4- 1] Authentication of the requesting UE L0 1:
This can be performed by successful identification of the requesting UE LOl by a
network or a UE with a proof from a network.
[0074] [4-2] Authentication of the receiving UE L03:
This can be performed by
[4-2-i] using a key shared between the requesting UE LOl and the receiving UE L03
[4-2-ii] using current network security keys or new keys
[4-2-iii] a network which informs the requesting UE LOl of the incoming authen
tication request from the receiving UE L03.
[0075] [5]Authorization - service access control (L5)
There should be different levels for access control to services that the requesting UE
LOl and the receiving UE L03 (hereinafter also referred to as "UE") can use within the
group.
[5-l]UE is allowed to receive and/or send a broadcasting message.
[5-2]UE is allowed to receive and/or send multiple messages.
[5-3]UE is allowed to receive and/or send a message for one-to-one communications.
[5-4] UE authorization according to subscription information and the policy UE set
for ProSe service.
[0076] A network can set up and provide the policy to the group members including the r e
questing UE LOl and the receiving UE L03 according to UE capabilities and user sub
scriptions.
[0077] The network 200 performs authorization for the UEs 100 want to join the group. The
group member of UEs 100 verify whether other UEs are authorized by the network by
using the session keys. Another method for performing validated authorization is done
by (1) a network sending an authorization value to each UE 100, and each UE 100 uses
this value to perform authorization on each other, or (2) Yet another method for
performing a validated authorization is done by sending an authorization value from a
requesting UE to a receiving UE, and then the receiving UE requests the Network to
validate this authorization value and receiving result.
[0078] [6] New key hierarchy and key management (L6)
A new key hierarchy is presented in this exemplary embodiment of the invention.
Key Kp is a key related to the group and also may related to a ProSe service. It has an
indicator KSI_p related to it. Kp can be sent from ProSe Server to use.
[0079] Keys, Kpc and Kpi are session keys that are derived from Kp at UEs. Kpc is a confi
dentiality key and Kpi is an integrity protection key. The session keys are used for UE
to perform authorization for each other, and ProSe communication setup, and have the
direct communication between them.
[0080] After authorization and authentication, the communicating devices including the requesting
UE L01 and the receiving UE L03 can start sessions to communicate with
each other. When the requesting UE L01 and the receiving UE L03 communicate with
each other, they should share communication keys. The keys can be a group key, and/
or a unique key per communicating device as well as a session key per each session.
[0081] The key can be managed by the network and sent over the secure communication
channel with the network. Alternatively, the key can be managed by the requesting UE
L01 and sent to other devices including the receiving UE L03 in the communication,
over a secure unicast communication channel that can be secured by the network
during authentication or verification. The key can also be issued by a third trusted
party.
[0082] The UEs 100 authenticate each other at the beginning of a session (S5). The authen
tication is linked to authorization (S6). Figs. 5A to 5C are schematic views showing
One-to-one, One-to-many, and Many-to-many sessions, respectively. As shown in
Figs. 5A to 5C, a UEa 2 1 and a UEa 3 1 indicate the requesting UE L01, and a UEb 22,
a UEb 32, a UEc 33 and a UEn_33n indicate the receiving UE L03.
[0083] When the session is started, firstly session keys are generated. In this exemplary em
bodiment, the requesting UE L01 (UEa 21, the UEa 31) and the receiving UE L03
(UEb 22, the UEb 32, the UEc 33, the UEn_33n) use two kinds of keys including
session keys.
Case IB:
Each group has a key Kp for each service (Kp is served as a service key) and a new
session key is created for each session.
Case 2B:
Each group has the key Kp (Kp is served as a group key), and a new session key is
created for each session.
[0084] In each case, either the ProSe server or the requesting UE L01 sends keys. For
example, the ProSe server sends the key Kp to the requesting UE L01 and the
receiving UE(s) L03, and the requesting UE L01 sends a session key to the receiving
UE(s) L03 every session. Alternatively, the ProSe server sends both of the key Kp and
the session key to the requesting UE L0 and the receiving UE(s) L03, or the requesting
UE L01 sends both of the key Kp and the session key to the receiving UE(s) L03.
[0085] Further, when the group changes if someone leaves or is added, when a session ends
or a key times out, or when the ProSe server has made a decision, for example, the key
Kp and/or the session key should be changed.
[0086] If the ProSe Server allocates the key Kp to UEs, UEs derive session keys from that
for authorization and communication. UEs can be pre-configured with algorithms for
key derivation, or the key Kp is related to a KSI (key set identifier) and a service.
Because of them, the security problems during UEs' authentication and authorization or
the security problems of a key for direct communication may be solved.
[0087] Note that the key set identifier (KSI) is a number which is associated with the cipher
and integrity keys derived during the authentication. The key set identifier can be
allocated by the network and sent with the authentication request message to the
mobile station where it is stored together with a calculated cipher key CK and an
integrity key IK. The purpose of the key set identifier is to make it possible for the
network to identify the cipher key CK and integrity key IK which are stored in the
mobile station without invoking the authentication procedure. This is used to allow r e
use of the cipher key CK and integrity key IK during subsequent connections (session).
[0088] [7] Secure Communication (L7)
Secure communication can provide message transmission availability between group
member UEs, as well as preventing a message from being eavesdropped on or altered
by UEs that do not belong to the group. Also the secure communication can prevent
UE from using an unauthorized service.
[0089] The communication within the group should have integrity and/or confidentiality
protection. All the communications can be protected by the session keys described
above, after the security association is established.
[0090] The security policy can be a negotiation and an agreement within the group with or
without the support of the operator network L02. All the group members should follow
the security policy.
[0091] Next, the security in the case where UEs' location change happens will be explained.
If none of UEs has a location change, there is no security issue. Further, if all of the
UEs have a changed location, but stayed in proximity to each other, then there is still
no security issue.
[0092] If a part of UEs (one or more UEs) have moved out of proximity from other UEs and
they do not use the ProSe service, group and security management need to be updated
for the remaining UEs in the group. Alternatively, if one or more UEs have moved out
of proximity from the UEs and they want to keep the ProSe service with each other,
group and security management need to be updated for the remaining UEs in the
group, and a new group and security are needed for the traveler.
[0093] Note that the ProSe Server should get UE location information from GMLC
(Gateway Mobile Location Center) periodically, to compare and compute the location
differences of all UEs.
[0094] [8] Termination (L8)
When the communication is to be suspended, devices should remove the session key
while keeping information of the authentication and authorization.
[0095] When the communication is to be terminated, the devices can keep history in
formation, or the allocated token with a lifetime for the next use time to prevent
signaling for authentication and authorization again.
[0096] Smooth handover from an infrastructure to a direct mode will require creation of a
key between communicating parties (the requesting UE LOl and the receiving UE L03)
before a handover happens. For example, if communicating parties are using WiFi, a
key should be allocated to WiFi AP and UEs. The WiFi AP and UEs should authorize
and authenticate each other. The key should have a limited life-time. A network can
recognize which WiFi AP the UE can communicate with. UEs can find that there is a
WiFi AP nearby and the network verifies the WiFi AP. UEs authenticate with the
ProSe Server when UEs connect to a WiFi AP. One option is that the ProSe Function
can allocate keys for the UEs to communicate with a ProSe APP Server.
[0097] To summarize the above description, the method of making a secure communication
of an exemplary embodiment includes the following features:
(1) The operator network L02 determines whether the requesting UE LOl can com
municate with the receiving UE L03 requested by the requesting UE LOl.
(2) Security in discovery of UEs in proximity can be provided by using a token, a
key, and signing provided by the network.
(3) Security in discovery of UEs in proximity can be provided by using a location
provided by the operator network L02.
(4) Security in discovery of UEs in proximity can be provided by using location in
formation provided by social network services, with security provided in an application
layer.
(5) Authorization of the devices can be performed by the network or by devices
direct verification.
(6) Mutual authentication between the requesting UE LOl and the receiving UEs that
agreed to be in the group L03 can be carried out by the network and also both UEs can
be informed with the result.
(7) Mutual authentication between the requesting UE LOl and the receiving UEs L03
can be carried out by both ends with a key shared there between.
(8) New keys for securing the ProSe communication which are a group key and a
unique session key can be used.
(9) Security policy in a group for secure communication is negotiated and set.
(10) Termination management can be performed to prevent the same keys from being
used and set up a security context for other communication.
[0098] According to the secure system of an exemplary embodiment, the operator network
L02 can determine the receiving UE(s) L03 with which the requesting UE LOl can
communicate, and can ensure secure discovery by either providing security parameters
to the requesting UE LOl or receiving UE L03, and providing location information of
the receiving UE L03 to the requesting UE LOl. Furthermore, the operator network
L02 can perform authentication and authorization for the requesting UE L01 and
receiving UE L03, and can support security association between UEs to secure ProSe
communication.
[0099] [9] A detailed method of performing the authentication and authorization
Next, a more detailed method of performing the authentication and authorization, and
establishing the security association with each other for the direct communication will
be explained.
[0100] As described above, there are three types of direct communication between UEs, i.e.
1) One-to-one, 2) One-to-many, and 3) Many-to-many as shown in Figs. 5A, 5B, and
5C, respectively.
[0101] A UEa is a Requesting UE. A UEb, a UEc, and other UEs are Receiving UEs. The
UEs set up direct communication with each other and protect the communication with
keys they share.
[0102] A new key hierarchy is presented in this invention. Key Kp is a key related to the
ProSe service ID, and has an indicator KSI_p related to it. Kp can be sent from the
ProSe Server to UEs in a ProSe Service Result message, or can be sent from the ProSe
Server when UEs are registered to the ProSe Server. Kpc and Kpi are session keys
derived from Kp at UEs. Kpc is a confidentiality key and Kpi is an integrity protection
key. The session keys are used for ProSe communication setup and the direct commu
nication between them.
[0103] Assuming that UEs are authenticated to the network and registered to the ProSe
Server. The Discovery procedure is completed as described above. The detail message
sequence and description of the three cases are given below.
[0104] [[Case 1C]] One-to-one direct communication
There are only two UEs in proximity having direct communication with each other.
In one-to-one communication, Kp can also be allocated to UEs at UE registration to
the ProSe server. Considering the one-to-one type of communication is rather for a
dynamic demand, not dedicated to a certain type of service, it is more efficient that the
ProSe server distributes the keys when the communication is required.
[0105] Fig. 6 is a sequence diagram showing One-to-one communication of an exemplary
embodiment of the present invention. As shown in Fig. 6, the system includes a UEa
31, a UEb 32, a ProSe server 34, and an operator network 36. The method includes the
following 12 steps.
[0106] SP20: The UEa 3 1 and the UEb 32 are pre-configured with key derivation al
gorithms, respectively.
SP21: When the Verification in [4] step 8 is successfully completed, the ProSe server
34 can allocate (an existing) or derive (a new) key Kp.
SP22: The ProSe server 34 sends Kp, KSI_p, UEb ID, and a service ID in the ProSe
Service Result to the UEa 31.
SP23: The ProSe server 34 sends Kp, KSI_p, UEa ID, and a service ID in the ProSe
Service Result to the UEb 32.
SP24: The UEa 3 1 derives the session keys Kpc and Kpi from the Kp which is
received from the ProSe server 34.
SP25: The UEa 3 1 sends ProSe Communication Setup to UEb 32 with a service ID,
KSI_p, UEa ID, and an algorithm for session key derivation. This message is integrity
protected with Kpi.
SP26: The UEb 32 derives the same session keys Kpc and Kpi from the Kp which is
received from the ProSe server 34. The UEb 32 can determine which Kp is to be used
according to the KSI_p and the service ID received in SP25.
SP27: The UEb 32 performs integrity check on the message received in SP25 with the
derived Kpi. The UEb 32 can also further check if the UEa ID and service ID are the
same as those received in SP23.
SP28: If the Verification at SP27 is successful, the UEb 32 sends a ProSe Commu
nication Accept with the service ID and UEb ID to the UEa 31. The message is
integrity protected with Kpi. It goes to SP30.
SP29: If the Verification at SP27 fails, the UEb 32 sends a ProSe Communication
Reject with the service ID, UEb ID, and a proper cause to the UEa 31.
SP30: The UEa 3 1 performs integrity check on the ProSe Communication Accept with
the Kpi. The UEa 3 1 can also further check UEb ID and service ID. Direct Commu
nication can start thereafter if the verification is successfully completed.
SP31: Direct communication starts between the UEa 3 1 and the UEb 32. The messages
can be confidentiality and/or integrity protected by the session keys Kpc and Kpi.
[0107] [[Case 2C]] One-to-many communication
There is a group of UEs having direct communication in which the requesting UE
can send broadcasting messages to other member UEs in the group, and other member
UEs can communicate with the requesting UE but do not communicate with other UEs
in the same group.
[0108] In this exemplary embodiment, two options for how Kp can be allocated to UEs will
be explained. The following is option 1 that Kp is sent from the ProSe server 34 in
ProSe Service Result, which is the same as in One-to-one communication shown in
Fig. 6.
[0109] Fig. 7 is a sequence diagram showing the option 1 of One-to-Many communication
of an exemplary embodiment of the present invention. As shown in Fig. 7, the method
includes the following steps.
[01 10] SP40: The UEa 31, the UEb 32, and the UEc 33 are pre-configured with key
derivation algorithms, respectively.
SP41: When the Verification in [4] step 8 is successfully completed, the ProSe server
34 can allocate (an existing) or derive (a new) key Kp.
SP42: The ProSe server 34 sends Kp, KSI_p, a UE ID list of the allowed UEs, and a
service ID in the ProSe Service Result to the UEa 31.
SP43a and SP43b: The ProSe server 34 sends Kp, KSI_p, UEa ID, UE ID list of the
allowed UEs, service ID in the ProSe Service Result to the UEb 32 and the UEc 33, re
spectively.
SP44: The UEa 3 1 derives the session keys Kpc and Kpi from the Kp which is
received from the ProSe server 34.
SP45a and SP45b: The UEa 3 1 sends ProSe Communication Setup to the UEb 32 and
UEc 33 with a service ID, KSI_p, UEa ID, and an algorithm for session key derivation,
respectively. This message is integrity protected with Kpi.
SP46: The UEb 32 and UEc 33 derive the same session keys Kpc and Kpi from the Kp
which is received from the ProSe server 34, respectively. The UEb 32 and UEc 33 can
determine which Kp is to be used according to the KSI_p and service ID received in
SP45a and SP45b, respectively.
SP47: The UEb 32 and UEc 33 perform integrity check on the message received in
SP45a and SP45b, respectively, with the derived Kpi. The UEb 32 and UEc 33 can
also further check if the UEa ID and service ID are the same as those received in
SP43a and SP43b, respectively.
SP48a and SP48b: If the Verification at SP47 is successful, the UEb 32 and UEc 33
send ProSe Communication Accept with a service ID and a UEb/UEc ID to the UEa
31, respectively. The message is integrity protected with Kpi. It goes to SP50.
SP49a and SP49b: If the Verification at SP47 fails, the UEb 32 and UEc 33 send ProSe
Communication Reject with the service ID, UEb/UEc ID, and a proper cause to the
UEa 31, respectively.
SP50: The UEa 3 1 performs integrity check on the ProSe Communication Accept with
the Kpi. The UEa 3 1 can also further check UEb/UEc ID and service ID. Direct Com
munication can start thereafter if the verification is successfully completed.
SP5 1: Direct communication starts between the UEa 31 and the UEb 32, or the UEa 31
and the UEc 33. The messages can be confidentiality and/or integrity protected by the
session keys Kpc and Kpi.
[0111] The following is the option 2 that receiving UEs (UEb 32, UEc 33) receive Kp at
registration to the ProSe server 34. In this option, the ProSe server 34 does not need to
send the ProSe Service Result to each of the receiving UEs (UEb 32, UEc 33). This
will save network resource when there are many UEs in the group for direct commu
nication.
[0112] Fig. 8 is a sequence diagram showing the option 2 of One-to-Many communication
of an exemplary embodiment of the present invention. As shown in Fig. 8, the method
includes the following 10 steps.
[0113] SP60: Kp is allocated to UEs when they are registered to ProSe server 34. The UEa
31, UEb 32, and UEc 33 are pre-configured with key derivation algorithms, r e
spectively.
SP61: The ProSe server 34 sends KSI_p, a UE ID list of the allowed UEs, and a
service ID in the ProSe Service Result to the UEa 31.
SP62: The UEa 3 1 derives the session keys Kpc and Kpi from the Kp.
SP63: The UEa 3 1 broadcasts ProSe Communication Setup to the UEs in the UE ID
list, with the service ID, UEa ID, UE ID list, and KSI_p. This message is integrity
protected with Kpi.
SP64: UEs having received the broadcast message sees if it is on the list, and derives
the same session keys Kpc and Kpi from the Kp. UEs can determine which Kp is to be
used according to the KSI_p and service ID received in SP63.
SP65: The UEb 32 and UEc 33 perform integrity check on the broadcast message
with the derived Kpi. The UEb 32 and UEc 33 can also further check the UEa ID and
service ID, if there are pre-configured criteria, respectively.
SP66a and SP66b: If the Verification is successful, the UEb 32 and UEc 33 send
ProSe Communication Accept with a service ID and UEb/UEc ID to the UEa 31, r e
spectively. The message is integrity protected with Kpi. It goes to SP68.
SP67a and SP67b: If the Verification fails, the UEb 32 and UEc 33 send ProSe Com
munication Reject with the service ID, UEb/UEc ID, and a proper cause to the UEa 31,
respectively.
SP68: The UEa 3 1 performs integrity check on the ProSe Communication Accept
with the Kpi. The UEa 3 1 can also further check the UEb/UEc ID and service ID.
Direct Communication can start thereafter if the verification is successfully completed.
SP69: Direct communication starts between the UEa 3 1 and the UEb 32, or the UEa
3 1 and the UEc 33. The messages can be confidentiality and/or integrity protected by
the session keys Kpc and Kpi.
[0114] [[Case 3C]] Many-to-many communication
In Many-to-many communication, each UE can communicate with any other UEs in
the group. Fig. 9 is a sequence diagram showing Many-to-many communication of an
exemplary embodiment of the present invention. As shown in Fig. 9, the method
includes the following 10 steps.
[0115] SP70: Kp is allocated to UEs when they are registered to the ProSe server 34. The
UEa 31, UEb 32, and UEn 33n are pre-configured with key derivation algorithms, r e
spectively.
SP71: The ProSe server 34 sends KSI_p, a UE ID list of the allowed UEs, and a
service ID in the ProSe Service Result to the UEa 31.
SP72: The UEa 3 1 derives the session keys Kpc and Kpi from the Kp.
SP73: The UEa 3 1 broadcasts ProSe Communication Setup to the UEs in the UE ID
list, with the service ID, UEa ID, UE ID list, and KSI_p. This message is integrity
protected with Kpi.
SP74: UEs having received the broadcast message sees if it is on the list, and derives
the same session keys Kpc and Kpi from the Kp, respectively. UEs can determine
which Kp is to be used according to the KSI_p and service ID received in SP73, r e
spectively.
SP75: The UEb 32 and UEn 33n perform integrity check on the broadcast message
with the derived Kpi, respectively. The UEb 32 and UEn 33n can also further check
UEa ID and service ID, if there are pre-configured criteria, respectively.
SP76a and SP76b: If the Verification is successful, the UEb 32 and UEn 33n send
ProSe Communication Accept with the service ID and UEb/UEn ID to the UEa 31, re
spectively. The message is integrity protected with Kpi. It goes to SP78.
SP77a and SP77b: If the Verification fails, the UEb 32 and UEn 33n send ProSe Com
munication Reject with the service ID, UEb/UEn ID, and a proper cause to the UEa 31,
respectively.
SP78: The UEa 3 1 performs integrity check on the ProSe Communication Accept with
the Kpi. The UEa 3 1 can also further check the UEb/UEn ID and service ID. Direct
Communication can start thereafter if the verification is successfully completed.
SP79: Direct communication starts between UEs. The messages can be confidentiality
and/or integrity protected by the session keys Kpc and Kpi.
To summarize the above description, a method of performing authentication and au
thorization of an exemplary embodiment includes the following features:
(1) New key hierarchy for UEs direction communication: Kp and session keys Kpc
and Kpi. Kpc is for encryption and Kpi is for integrity protection. Both Kpc and Kpi
are derived from Kp.
(2) Kp is related to a key identifier KSI_p and also a service ID, such that UEs can
keep the synchronization and verify whether the key is proper for the requested
service.
(3) The ProSe server distributes Kp to UEs when UEs are registered to the ProSe
server, or in the ProSe Service Result message.
(4) UEs are pre-configured with algorithms for session key derivation. By the KSI_p,
service ID and indicated algorithm, the receiving UEs can derive the same session
keys.
(5) Integrity key Kpi is used to protect the communication request from the r e
questing UE, such that the receiving UE can perform integrity check and verify
whether the message is from an authorized source.
(6) Receiving UE can also verify whether all the service ID, the requesting ID, and the
key match.
(7) ProSe Communication Accept is integrity protected by the receiving UE such that
the requesting UE can verify its integrity.
(8) Direct communication between UEs can be confidentiality and/or integrity
protected with the session keys Kpc and Kpi.
[01 17] According to the secure system of an exemplary embodiment the invention, the key
distributed from a network element ProSe server enables the UEs which want to
establish direct communication to verify whether the other UEs are authorized to have
the service. The UEs derive session keys at their ends can prevent keys from being
stolen or altered if they are sent from one UE to another. The Kp is related to a certain
service, which prevents the UEs from using the key for other services which they may
not be authorized to have. The direct communication between UEs can be secured with
the session keys that are shared only between the UEs.
[0118] This software can be stored in various types of non-transitory computer readable
media and thereby supplied to computers. The non-transitory computer readable media
includes various types of tangible storage media. Examples of the non-transitory
computer readable media include a magnetic recording medium (such as a flexible
disk, a magnetic tape, and a hard disk drive), a magneto-optic recording medium (such
as a magneto-optic disk), a CD-ROM (Read Only Memory), a CD-R, and a CD-R/W,
and a semiconductor memory (such as a mask ROM, a PROM (Programmable ROM),
an EPROM (Erasable PROM), a flash ROM, and a RAM (Random Access Memory)).
Further, the program can be supplied to computers by using various types of transitory
computer readable media. Examples of the transitory computer readable media include
an electrical signal, an optical signal, and an electromagnetic wave. The transitory
computer readable media can be used to supply programs to computer through a wire
communication path such as an electrical wire and an optical fiber, or wireless commu
nication path.
[01 19] This application is based upon and claims the benefit of priority from Japanese Patent
Application No. 2013137293, filed on June 28, 2013, the disclosure of which is in
corporated herein in its entirety by reference.
Reference Signs List
[0120] 1 secure system
10 system
1 1 UE
12 UE
13 E-UTERN
14 EPC
15 ProSe Function
16 ProSe APP Server
17 ProSe APP
18 ProSe APP
19 eNB
20 eNB
2 1 UEa
22 UEb
3 1 UEa
32 UEb
33 UEc
33n UEn
34 ProSe server
36 operator network
100 UE
100a system
100b system
200 network
L01 requesting UE
L02 operator network
L03 receiving UE
LI secure group management
L2 secure discovery
L3 initial authorization
L4 authentication
L5 authorization
L6 security association establishment
L7 secure communication
L8 termination

Claims
[Claim 1] A method of performing authentication and authorization in Proximity
based Service (ProSe) communication by a requesting device which
sends a request of a communication and a receiving device which
receives the request from the requesting device, the method
comprising:
deriving session keys Kpc and Kpi from an unique key Kp at the r e
questing and receiving devices;
using the session keys Kpc and Kpi for ProSe communication setup and
direct communication between the requesting and receiving devices;
and
starting the direct communication with the requesting and receiving
devices,
wherein the key Kpc is confidentiality key and the key Kpi is integrity
protection key.
[Claim 2] The method of performing authentication and authorization in ProSe
communication according to claim 1 further comprising:
requesting a ProSe service request to the ProSe server from the r e
questing device;
performing a discovery procedure by the ProSe server to obtain
location information of the receiving device; and
sending a ProSe service result to the requesting and receiving devices,
wherein the key Kp is sent from the ProSe Server to the requesting and
receiving devices in the ProSe service result.
[Claim 3] The method of performing authentication and authorization in ProSe
communication according to claim 2,
wherein the direct communication is one-to-one communication
between the requesting and receiving devices.
[Claim 4] The method of performing authentication and authorization in ProSe
communication according to claim 2,
wherein the direct communication is one-to-many communication
between the requesting device and a plurality of the receiving devices
in a same group, and
wherein the requesting device can send broadcasting messages to other
receiving devices in the same group, and other devices can send
broadcasting messages to the requesting device but cannot send
broadcasting messages each other.
WO 2014/208035 PCT/JP2014/003167
[Claim 5] The method of performing authentication and authorization in ProSe
communication according to claim 1 further comprising:
sending the key Kp from the ProSe Server when the requesting and
receiving devices are registered to the ProSe Server;
requesting a ProSe service request to the ProSe server from the r e
questing device;
performing a discovery procedure by the ProSe server to obtain
location information of the receiving device; and
sending device ID list of allowed receiving devices, service ID in a
ProSe service result to the requesting device.
[Claim 6] The method of performing authentication and authorization in ProSe
communication according to claim 2,
wherein the direct communication is one-to-many communication
between the requesting device and a plurality of the receiving devices
in a same group, and
wherein the requesting device can send broadcasting messages to other
receiving devices in the same group, and other devices can send
broadcasting messages to the requesting device as well as each other.
[Claim 7] A secure system including a plurality of User Equipments (UEs), and a
Proximity based Service (ProSe) server comprising:
a requesting device which sends a request of a communication; and
a receiving device which receives the request from the requesting
device,
wherein
the requesting and receiving devices derive session keys Kpc and Kpi
from an unique key Kp;
the requesting and receiving devices use the session keys Kpc and Kpi
for ProSe communication setup and direct communication between the
requesting and receiving devices; and
the requesting and receiving devices start the direct communication
with the requesting and receiving devices,
wherein the key Kpc is confidentiality key and the key Kpi is integrity
protection key.