Survey on Authentication Protocols for Mobile Devices by lca18343


									Survey on Authentication
Protocols for Mobile Devices

 Muhammad Hasan, Lihua Duan, Tarik El Amsy
              Course :60-564
       Instructor: Dr. A. K. Aggarwal
                Winter, 2006
 Introduction
 Background Information
 Discussion of the Selected Papers
 Testing Methodologies
 Conclusion
 References
 Challenges on security and quality of service (QOS)
  of Wireless Networks:
      Unprotected open mediums
      Burst volume of communications
 IETF AAA Working Group
 AAA (Authentication, Authorization, and
  Accounting )
 Several AAA protocols proposed :
      RADIUS
  RADIUS (Remote Authentication Dial In User Service)

 Based on UDP.
 Client/server protocol.
 Takes care of Server availability, Retransmission, and
 Details found at : RFC 2865.
 RADIUS Packet
The Whole Packet :

MAC          IP header     UDP            RADIUS      Data ::
header                     header         header

 RADIUS Header :
     Code            ID                      Length


 Improvement over RADIUS
 Uses reliable transport protocols (TCP or SCTP)
 It uses transport level security (IPSEC or TLS)
 support for RADIUS
 It has larger address space for AVPs (Attribute Value
  Pairs) and identifiers (32-bit instead of 8-bit)
 peer-to-peer protocol, not client-server : supports
  server-initiated messages
 Details found at :   RFC 3588
   Diameter Packet
The Whole Packet :

 MAC          IP header    TCP header Diameter       Data ::
 header                               header

Diameter Header :
             Version                       Msg. Length
             Flags                            Code
                          Application ID
                          Hop by Hop ID
                          End to End ID
                            AVP []…..
The General Architecture
   Inter-network & intra-network roaming

Inter-network roaming takes place When the user moves from one ISP to another ISP
Intra-network roaming takes place when the user moves from cell to cell within the ISP.

                   Home                                          Visitied
                Network ISP                                    Network ISP

                                                      AAA server
           AAA server

                                                                             Cell 2

     Home Network user
                                  Inter-network                        Cell 1
   Existing GSM Authentication

        Mobile Client                  VLR/LAS                           HLR/HAS

                     IMSI                                  IMSI
                                                  IMSI, K t , RAND, SRES
                   K t ( TMSI )


VLR : Visiting Location Register         RAND : A Random Number Generated by HLR
HLR : Home Location Register              SRES : KA, RAND (Encrypted with one-way fn)
IMSI : International Mobile Subscriber Identity    Kt : temporary authentication key
TMSI : Temporary Mobile Subscriber Identity
Strong Password Protocols

  The aim of strong password protocols is to
   authenticate the user while protecting the
   password against dictionary attacks by online
  Two earlier strong password protocols : EKE
   and protocol of Gong. et al.
EKE (Encrypted Key Exchange) Protocol :

   It provides secure authentication between user and a
    server using a weak secret.
   Generates per session public- private key pairs.
   Major Drawback : Doing private key operations on
    client side makes it infeasible to use with
    computationally restricted devices ( Mobile devices).
   In 2002 Zhu et al. presents a variant of RSA-EKE for
    mobile devices.
The protocol of Gong et al.
 Contains a trusted third party which is
  continuously available online as in Kerberos.
 The parties in the system authenticate each
  other by the help of the trusted server.
Paper 1

     GSM User Authentication

 By Özer Aydemir, Ali Aydın Selçuk
      TÜBTAK UEKAE         Dept. of Computer Eng.
  LTAREN Research Center     Bilkent University
      Ankara TURKEY          Ankara TURKEY
Paper 1 :GSM User Authentication Protocol

 Objectives :
     User can authenticate with his/her password
      instead of the embedded key.
     Breaks the dependency on the SIM card
      during authentication.
     Users will be able to reach their accounts
      without their SIM cards, via any cellular phone,
      Internet, or a special network
GUAP ( Cont. )

 Resembles the approach of Gong et al.
 Three entities involved in the authentication.
 VLR plays the trusted server role
 Random nonces for freshness guarantee
of the sessions.
   Functionality of GUAP
Mobile Client                    VLR                                         HLR


 EHLR { n1, n2, c, Π (RAND) }, rA        EHLR { n1, n2, c, Π (RAND)} K VLR (RAND)
  Π (n1, n2 EXOR K), K(rA), rB                 K VLR (K), Π (n1, n2 EXOR K)

Π i : Password of user i
Ex{p}: Public key encryption of plaintext p with the key of x
K(p): Symmetric key encryption of plaintext p with key K.
n1, n2, c : Three random nonces generated by mobile client
K : Session key
rA, rB : Challenges
Security Issues :
 The existence of the correct n1 value in the fifth
  message indicates that it is the HLR that has
  decrypted the first message and sending this output.
 The random nonce n2 protects HLR’s response
  encrypted by π against dictionary attacks on π by an
  attacker who gets to know k or by VLR.
 Random c protects first message against
  regeneration by VLR.
    Paper 2

     Improving mobile authentication with
         new AAA protocols

    by H. Kim and H. Afifi
    Proc. IEEE Int. Conf. on Communications, May 2003
    An authentication protocol by combining the AAA framework
     and the USIM authentication mechanism
AAA + USIM Authentication Protocol
 MU         LAS                         PAS/AAA Broker                                HAS

                           (1)                                     (2)
    First request                       Verify UPC
                    Request-challenge                      Forward + UPC
                           (4)                                      (3)            Generate AVs = (User,
                                        Store AVs
                    Challenge (REND1)                           Send AVs           REND, XRES)s

 Compute RES1       Response (RES1)     RES1 = XRES1
                                        Eliminate AV1
 A New Request                          Verify User ID

                                        Utilize AV2
                    Challenge (REND2)

 Compute RES2       Response (RES2)     RES2 = XRES2

                                        Eliminate AV2
    UPC: USIM-PROXY-CAPABILITY;                       AV: Authentication Vector;
    REND: random number;                              XRES: Expected Response;
    RES: Response
Some Issues
  request message is forwarded to HAS
  through LASs
 One of PASs can choose to become a broker
  by checking if UPC field exists in the request
 The number of AVs generated at HAS is an
  optimization problem
 Paper 3

A lightweight authentication protocol
     with local security association
     control in mobile networks
      by W. Liang and W. Wang
      Proc. IEEE Military Communications Conference, 2004
      An authentication protocol by introducing local security
       association with optimal life time for mobile user
        Authentication with Local Security Association

                               MU                               LAS                             HAS


                                            Response                                             Verify
                                                            Generate SA
                                          Reply(SAKul)                             Reply(Kul)
                                                                                             Kul || ALGORITHM || F0 || {R1, ALGORITHM , F0}K0
               New Request
                                                                 Verify                               Kul  HMAC  MD5( K0 ,{R1 || IDMU })


                                                         Terminate SA when
                                                         MU's out of network

                          LAS: Local Authentication Server                     K0: pre-defined shared key for MU and HAS
                          HAS: Home Authentication Server                      Kul: new shared key for MU and LAS
                          SA: Security Association                             F0: session random number against replay attack
                          MU: Mobile User                                      R1: random number
 Refresh Local Security Association

• When the local security association expires, LAS will refresh
it by sending to mobile user a new key and a new life time

      K ul  HMAC  MD5( Kul ,{R2 || IDMU })

• An optimal life time of the local security association is critical
for the efficiency of the authentication

     the risk to crack the key is increasing as the life
    time is increasing
     the cost to refresh
Paper 4

  Localized Authentication for Wireless
        LAN Inter-network Roaming

By Men Long , Chwan-Hwa “John” Wu , J. David Irwin
 Department of Electrical and Computer Engineering
                 Auburn University
 Localizing the Authentication
 A new approach in which an initial mutual authentication
  between a visited network and a roaming user can be
  performed locally without any intervention by the user’s
  home network.
 Advantages are low time delay and robustness.

 A practical certificate structure x.509
 Authentication adapts the SSL v3.0 handshake protocol.
 Local AAA server will approve or reject the authentication
  request. Home network AAA will not be part of the
Local Authentication Handshake Messages

 Flow 1 “client Hello”
 Flow 2 “ server Hello”
 Flow 3 “Finished”

         Roaming User
                                                       Visited Network

                                      NU , D

                                 NS , CertS

               EncPKs(k),Ek1 (CerU),SignSu (NS ||NU S || U)
Protocol flow
 Message flow (1) (NU , D )
 same as “ClientHello” in SSLprotocol:
 The user sends a random number NU as user nonce along with
   D domain name of the roaming user.

 Message flow (2) (NS , CertS )
 same as “ServerHello” in SSL protocol:
 The AAA server will attempt to find its public key certificates
  CertS signed by domain D received in message 1 and sends the
  certificate CertS and server’s nonce NS to the user.
 If it did not find a certificated signed by D then it will abort the
  session because there is no roaming agreement with this
  domain and the user get rejected.
  Message flow (3):
 The user employs his home network’s public key to verify the CertS.
 The user chooses a random number k as the pre-master secret and
  then encrypts it by Enc PKS (k) using the visited network’s public
  key PKS in CertS.
 The user’s terminal applies a pseudo random function to the pre-
  master secret to derive a key k1.
 Then k1 encrypts the user’s certificate CertU by EK1 (CertU) via a
  symmetric cipher such as the AES-128 with an appropriate mode.
 Finally, the user signs the message NS || NU|| S|| U using his private
  key SU, by DSA or the RSA methods.

       EncPKs(k) + Ek1 (CerU) + SignSu (NS ||NU || S || U)
     Pre-master key Encrypted User Certificate   Signature message
Authentication Key Establishment
   The Visited network will Decrypt to obtain the pre-
    master secret k using its own private key SKs.
   It then applies the publicly known pseudorandom
    function to the pre-master secret to derive k1.
   Use k1 to decrypt and obtain the user’s certificate.
   The visited network will validate & verify the
    authenticity of the user’s public key certificate and
    then the validity of the user’s signature.

     EncPKs(k),Ek1 (CerU),SignSu (NS ||NU || S || U)
Security Feature Comparison

                        WiFi & GSM   Local Authen.

 Time overhead due
to com. b/w Home &         Yes           No
   Visited network
Impact resulting from
home network failure     Maximum      Minimum

  Visited network
  learns roaming           Yes           No
   user’s secret
Strong authentication
against cryptanalysis      No            Yes
                                                             Paper 1
Testing Methodologies
 The HLR and VLR are simulated on a 2.4 GHz Pentium IV machine,
  and the mobile client runs on Sun’s KToolbar v.2.0 simulation toolkit
 The simulations are implemented in Java2 Standard Edition (J2SE) for
   HLR and VLR, and in Java2 Mobile Edition (J2ME) for the mobile client.
 The cryptographic functions are inherited from the Bouncy Castle
   Lightweight Crypto API for both J2SE and J2ME.
                                            Paper 2
Testing Methodologies
 Consists of LAS, AAA broker, and HAS.
 They are geographically separated and connected by
 The performance of the proposed authentication
  protocol is evaluated by measuring the time spent for
 Two suites of experiments are performed according to:
      the number of users
      the number of proxy agents.
 The gathered results reduces the spent time
   considerably compared with DIAMETER protocols.
                                                            Paper 4
Testing Methodologies
   Paper 4 , Localized Authentication Testing Methodology
   2 phases
   Phase I, with a Pentium 4 (2.2 GHz) and 512 MB
   RSA encryption or signature verification time is 0.28 milliseconds
    while the RSA decryption or signature-signing time is 5.53
   Phase II ( SSL/TLS protocol ) .
   laptop Pentium 4 (1.8 GHz) & 256 MB memory and IMAP server
   The results indicate that the time delay per SSL channel setup
    averages 24 milliseconds.
   According to the data from the phases 1 and 2, the expected time
    delay for the proposed protocol is about 30=24+6 milliseconds.
                                                                            Paper 3
Testing Methodology
             the total authentication cost by processing all the authentication
      C (T ) is
      request sent by roaming MUs.
      is the arrival rate of authentication request to initiate a new
      network service.
      is the average residence time of a roaming MU in the foreign
     T is the life time of a security association (SA).
     cc is the signaling cost to refresh a local SA.
     cm is the cost for remote authentication.
      cn is the cost for local authentication.
     cr is the cost to compensate the risk that SA is cracked.
      is the factor of increasing risk.

                        cm , T  0
                       T    cc
  C (T )   (Tcn  cr e )        cm , 0  T  
           T                   T
                  cn  cr e T , T  
                                         Paper 3
Testing Methodology-cont.
 Suppose there are 10 hops for remote
 DIAMETER, RADIUS, EKE and Gong et al.’s are
  some of the earliest standardized AAA authentication
 To improve efficiency or adaptability, many new
  authentication protocols are proposed in the
  literature. We discuss four most recent ones.
      For those protocols aiming at improve efficiency, they
       usually share one common feature: reduce the number
       of remote authentications by transforming them into
       local authentications.
      For those protocols aiming at improve adaptability,
       they often try to relax some hardware limitation for
       authentication, such as the use of SIM card.
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Special Thanks to:

        Dr. A.K. Aggarwal
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