在电脑网路应用环境中的身份认证与金钥协议技术之研究

1、1在電腦網路應用環境中的身份認證與金在電腦網路應用環境中的身份認證與金鑰協議技術之研究鑰協議技術之研究 Advisor: Dr. Chin-Chen Chang Student: Hao-Chuan Tsai Date: 12.30.2010 Department of Computer Science and Information Engineering, National Chung Cheng University2 Part I: Authentication Scheme with Key Agreement three party authenticated key agreem

2、ent Part II: Anonymous Authentication Scheme for Wireless Networks34 Goal: Convince system of your identity before it can act on your behalf Methods Who you are What you know What you have5 What you have Verify identity based on possession of some object Magnetic Card Smart Card (IC Card)8.56cm5.39c

3、m1.923cm1.025cm6Who you areverify identity based on your physical characteristics or involuntary response patterns known as biometrics characteristics used include: signature (usually dynamic) fingerprinthand geometry face or body profile speech retina pattern always have tradeoff between false reje

4、ction and false acceptance 7What you knowBirthday, School name, Blood type, or Salary ?Meaningful Secrets ?Meaningless Secrets (Passwords) !Traditional Password MechanismProcedure: 1. Prompt user for a login name and password 2. Verify identity by checking that password is correct Passwords in the S

5、ystem: May be stored in clear mode May be stored in cipher mode: Encrypted or One-Way HashedPasswords should be selected with care to reduce risk of exhaustive search One problem with traditional passwords is caused by eavesdropping their transfer over an insecure network 8 Password Practice Passwor

6、d Complexity Criteria At least 7 characters long. Does not contain your User Name, Real Name, or Company Name. Does not contain a complete dictionary word. Is significantly different from previous passwords. Contains characters from each of the following groups: uppercase letters lowercase letters n

7、umerals symbols found on the keyboard.9 Create Session Keys Key transport A session key is selected by one communication party and is distributed to others in some way Key agreement A session key is established by the cooperating of all communication parties10Drawbacks of 2PAKA Given N parties there

8、 are N(N-1)/2 (=nC2) secret keys that should be established each party should securely store N-1 secret keys Awkward for larger-scale networks Inflexible (difficult to add, update, or delete a party)ExampleIf N = 6, then there are 6(6-1)/2 = 15 secret keys should be established in advance.11An authe

9、nticated key agreement protocol is an interactive method for two or more parties to determine session keys based on their secret keys or public/private keys.AuthenticationAuthenticationKey agreement / key exchangeSKSecure communication Trusted server1213 Impersonation attacks Impersonate clients or

10、the server Man-in-the-middle attacks On-line password guessing attacks Off-line password guessing attacks The most powerful attack14 The server needs to authenticate the communication clients explicitly The established session key would not revealed to either the server or others Round efficiency15

11、Initial phase The server computes And then the server computes Server also finds a value rc to satisfy the equationand computes (,)CCHCpw( ,)CH C skm o dCCCrqm o dCrCgp16ABS1.2.1ApwxXgM2(| )xxAXgHgA B1Bp wyYgN2(|)yyBYgHgB A1ApwxXgM2(| )xxAXgHgA B17ABS3compute,(|)xyzABskHABSg/ApwxgX M/BpwygY Nretriev

12、e derive (|)xAHgA B(|)yBHgBA)|(|)|(AyzpwAxyzgHgSBAHgXA)|(|)|(BxzpwByxzgHgSABHgYB4)|(|)|(BxzpwByxzgHgSABHgYBcompute,(|)xyzABskHABSg1819H L R1VLR2VLR3VLRMSMSMSRoaming path20Multiple regional domainEach domain is operated under a different administrationHLR (Home Location Register)HLR is used to denote

13、 the home domain, the home domain server, and the home location register, concurrently.A subscriber has only one home as his administrative domain One who desiring to contact MS must consult his HLR. VLR (Visiting Location Register)VLR is used to denote the visiting domain, the visiting domain serve

14、r, and the visiting location register, concurrently.When a subscriber roams into a visited domain, he should initially establish a residence within that domain.21HLRMSVLRIMSIIMSI, VLRIMSI, (RAND1, SRES1, Kc1), (RAND2, SRES2, Kc2), , (RANDn , SRESn, Kcn).RAND1SRES1 enc_with_ A5(Kc1, TMSI)Computes: SR

15、ES1 = A3(Ki, RAND1), Kc1 = A8(Ki, RAND1) SRES2 = A3(Ki, RAND2), Kc2 = A8(Ki, RAND2) SRESn = A3(Ki, RANDn), Kcn = A8(Ki, RANDn) Computes: (inside SIM) SRES1 = A3(Ki, RAND1) Kc1 = A8(Ki, RAND1) Computes: enc_with_ A5(Kc1, TMSI) Decrypts: enc_with_ A5(Kc1, TMSI)(Unspecified Secure Channel)Multiple on-t

16、he-fly triplets s h o u l d b e o n - l i n e generated and transferred in batch to the VLR. Then, VLR can use them in successive authentication flows with the roaming MS.VLR needs to ensure that MS is currently in good status. MS establishes a temporary residence in the visited domain.22VLRTMSIRAND

17、mSRESm Computes: (inside SIM) SRESm = A3(Ki, RANDm) Kcm = A8(Ki, RANDm) enc_with_A5(Kcm, messages)MSVLRTMSI, RANDmSRESm Computes: (inside SIM) SRESm = A3(Ki, RANDm) Kcm = A8(Ki, RANDm)enc_with_A5(Kcm, messages)MSWhen MS makes a call, the origination protocol is then invoked to authenticate himself t

18、o VLR and establish a session key.23242526 The main problems we suffer Impersonation Attack Attackers can impersonate either MS or FA to obtain secret information Personal Privacy Problem The identity of MS can be revealed to others27 The proposed scheme has the following characteristics Provide mut

19、ual authentication A mobile client and the communicating entities can be authentic An established session key would not revealed to either the uninvolved servers or others Diverting the most complicated operations to either the HLR or VLR The risk of compromising the secret information stored on HLR is reduced Ensure anonymity28 Initial phase Sh choose