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Advanced Secret Handshake Protocols in Network Security

This presentation explores advanced techniques in network security focused on secret handshake protocols. It details the objectives of authenticating two parties without revealing their credentials and outlines scenarios involving distinct user groups. The session covers the use of pairing-based cryptography, bilinear maps, and one-way hash functions to ensure secure communications. Key protocols, such as the Secret-Handshake Scheme (SHS) and Pairing-Based Handshake (PBH), are discussed, along with their implementation, user management, and robustness against attacks while maintaining user privacy.

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Advanced Secret Handshake Protocols in Network Security

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  1. CSC 774 Advanced Network Security Topic 2.5 Secret Handshake Slides by Tong Zhou Dr. Peng Ning

  2. Goals • Authenticate without revealing credentials • Consider two groups G1 and G2, two parties AG1 and B G2. A and B wants to authenticate each other. • If G1 ≠ G2: A and B only know they are not in the same group. • If G1 = G2: A and B can authenticate to each other. • A third party learns nothing by observing conversations between A and B. Dr. Peng Ning

  3. Preliminaries: Pairing-based Cryptography • Bilinear Maps: • Two cyclic groups of large prime order q: G1 and G2 • is a bilinear map if • ê should be computable, non-degenerate and satisfies Bilinear Diffie-Hellman assumption, i.e., given P, aP, bP, cP, it is hard to compute Dr. Peng Ning

  4. Protocol Sketch • Equipped with bilinear map ê and one-way hash function H1 • CA has a master key t. • Assume a drivers and cops scenario. Dr. Peng Ning

  5. xy6542678d p65748392a Protocol Sketch Please show me your pseudonym. Driver’s licence, please. Driver’s Licence: “p65748392a”,TA Traffic cop credential: “xy6542678d”,TB TB = tH1(“xy6542678d-cop”) TA = tH1(“p65748392a-driver”) Dr. Peng Ning

  6. This guy is not a cop. xy6542678d p65748392a Protocol Sketch – Attacker Igor ??? Please show me your pseudonym. I am a cop. Driver’s licence, please. Driver’s Licence: “p65748392a”,TA Obtains Bob’s pseudonym “xy6542678d” TA = tH1(“p65748392a-driver”) Dr. Peng Ning

  7. Secret-Handshake Scheme (SHS) • SHS.CreateGroup(G): executed by an administrator, generates the group secret GroupSecretG for G. • SHS.AddUser(U,G,GroupSecretG): creates user secret UserSecretU,G for new user U. • SHS.HandShake(A,B): Users A and B authenticates each other. B discovers A G if and only if Adiscovers BG. • SHS.TraceUser:Administrator tells the user from a transcript T generated during conversation between A and B. • SHS.RemoveUser: Administrator revokes user U Dr. Peng Ning

  8. Pairing-Based Handshake (PBH) • PBH.CreateGroup: Administrator sets GroupSecretG as a random number • PBH.AddUser: Administrator generates a pseudonyms for user U: and then generates the corresponding secret points: where H1 is a one-way hash function. Dr. Peng Ning

  9. A A A B B B Pairing-Based Handshake (PBH) • PBH.Handshake: Dr. Peng Ning

  10. Pairing-Based Handshake (PBH) • PBH.TraceUser: Since the conversations of handshaking include the pseudonyms, administrator can easily figure out the users. • PBH.RemoveUser: Administrator removes user U by broadcasting its pseudonyms to all the other users, so that other users won’t accept pseudonyms of U. Dr. Peng Ning

  11. Computational Diffie-Hellman Instead of Bilinear Diffie-Hellman • CreateGroup: Administrator picks (p,q,g). p and q are primes, g is a generator of a subgroup inof order q. Also, picks up a private key x, and computes the public key y=gx mod p • AddUser: For user U, administrator generates idU, then generates a pair so that idU, w, t will be given to the user. Dr. Peng Ning

  12. Computational Diffie-Hellman Instead of Bilinear Diffie-Hellman • How to generate the pair (w,t)? Randomly pick r, compute Dr. Peng Ning

  13. Computational Diffie-Hellman Instead of Bilinear Diffie-Hellman • Handshake: Assume user A has (idA, wA, tA) and user B has (idB, wB, tB). Define several marks (ElGamal Encryption): Dr. Peng Ning

  14. A A A A B B B B randomly picks computes randomly picks computes Computational Diffie-Hellman Instead of Bilinear Diffie-Hellman • Handshake: verifies respb verifies respa Dr. Peng Ning

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