Wireless Body Area Networking


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Wireless Body Area Networking

  2. 2. Overview  Wireless Body Area Network  Challenges  Security Requirements  Possible Solutions  Identity Based Encryption  Weil Pairing  Tate Pairing  Weil Pairing Vs. Tate Pairing  Conclusions
  3. 3. Wireless Body Area Network • It is the integration of intelligent, miniaturized, low power sensor node in, on or around a human body to monitoring body function • Different nodes such as ECG, EMG and EEG are deployed on the human body to collect the physiological parameters and forward them to a remote medical server for further service • WBAN consist of two types:- 1) In-body area network 2) On-body area network ( Security in Wireless Body Area Networks: A survey by M. Somasundaram+ and R. Sivakumar )
  4. 4. Challenges  Sensor nodes are Low energy devices  Security threats  Data consistency  Interference  Cost  Consistent performance
  5. 5. Possible Security Threats and Attacks Layers DoS Attacks Defenese Physical Jamming Tampering Spread-spectrum, priority messages, lower duty cycle, region mapping, Tamper-proof, hiding Link Collision Unfairness Exhaustion Error correcting code Small frames Rate limitation Network Spoofing Selective Forwarding Sybil Encryption Egress filtering, authorization monitoring Authorization, monitoring, redundancy Transport Flooding De-synchronization Client Puzzles Authentication
  6. 6. Security Requirements  Data integrity  Data Authentication  Data freshness  Secure localization  Availability  Secure management  Data confidentiality • In WBAN, data confidentiality is considered to be the most important issues. • Protect the data from disclosure. • Should not leak patient’s vital information to external or neighboring networks. • To solve this security risk public- key cryptography is too costly.
  7. 7. Possible Solutions  Identity based encryption scheme is used to achieve Data confidentiality in Wireless Sensor Networks. Importance of using IBE: • Ideal for low energy sensor devices • Reduces cost  Elliptic Curve Cryptography  Bilinear Pairing Function
  8. 8. Identity Based Encryption ALICE BOB PKG C M skIDbob Upon receiving IDbob M ID bob pkPKG Sender Receiver IBE has 4 steps :- 1) Setup 2) Private key Extraction 3) Encryption 4) Decryption ( A Survey of Identity-Based Cryptography by Joonsang Baek, Jan Newmarch, Reihaneh Safavi-Naini, and Willy Susilo)
  9. 9. Elliptic Curve • Two families of elliptic curve E for use in pairing based cryptosystems: 1. The pairing takes values in the prime field Fp over which the curve is defined. 2. This family consists of super singular curves with embedding degree k=2 Let E be the elliptic curve Y2=x3+ax+b Defined over a finite field Fq, and let p be a base point having prime order n dividing #E(Fq), where we assume that n does not divide q. • Usefulness of Elliptic curve in IBE: Elliptic curve divide the keys (public key) one half or one forth then the power consume and energy loss decreases in case of key exchange
  10. 10. Bilinear Pairing • Bilinearity : ȇ(aP , bQ)=ȇ(P , Q)ab, where P , Q Є G and a,b Є Zq * • Non-degenerate: ȇ does not send all pair of points in G * G to the identity in F(Hence if R is a generator of G then ȇ(R,R) is a generator of F) • Computable: For all P , Q Є G the map ȇ(P , Q) is efficiently computable • Type of Bilinear pairing: Diffie-Hellman problem: Given( G, q, ȇ, P, aP, cP) where a,b and c are chosen at random from Zq * compute ȇ(P,P)abc Other billnear pairing: 1) Boneh and Frankin’s IBE 2 ) Hierarchical IBE scheme 3) Cha and Cheon's IBE Scheme
  11. 11. Selected IBE Schemes • Weil Pairing : In mathematics, the Weil pairing is a pairing on the points of order dividing n of an elliptic curve E, taking values in nth roots of unity. More generally there is a similar Weil pairing between points of order n of an abelian variety and its dual. • Tate Pairing : The Tate pairing was introduced by G. Fray and H.G. Ruck. Tate pairing was firstly used to construct FR attack. Tate pairing is now an alternative to Weil pairing due to its somewhat better computation efficiency.
  12. 12. Weil Pairing Weil pairing have 4 stages:- 1. Setup 2. Extract 3. Encryption 4. Decryption (Identity-Based Encryption from the Weil Pairing by Dan Boneh Matthew Frankliny )
  13. 13. Weil Pairing (Contd…) Setup : The PKG specifies • A group G generated by P Є G* and the bilinear pairing ȇ: G * G  F • Two hash functions H1 : {0,1}*  G* and H2 : F {0,1}l where l denotes the length of a plaintext • PKG then picks a master key s Є Zq * at random and computes a public key PPKG = sP Private key extraction: • Bob,the receiver ,then contacts the PKG to get his private key DID = sQID where QID= H1(ID)
  14. 14. Encryption: Alice the sender, can now encrypt her message M {0,1}l using Bob’s identity ID by computing U=rP and V=H2 (ȇ(QID, PPKG)r) M, where r is chosen at random from Zq * and QID = H1(ID). Decryption: • The resulting cipher text C=(U,V) is send to Bob • Bob decrypts C by computing M=V H2 (ȇ(DID, U)) Weil Pairing (Contd…)
  15. 15. Tate Pairing Definition: Tate pairing is essentially a bilinear map from G1 * G2  G3 where G1 = S[q], G2 =T[q] and G3 is the multiplicative group of GF(p2) Stages of ID based Tate pairing:- 1. Setup 2. Extract(Registration) 3. Encrypt 4. Decrypt (An Identity based Encryption using Elliptic Curve Cryptography for Secure M2M Communication by B S Adiga, Balamuralidhar P,Rajan M A, Ravishankara Shastry, Shivraj V L)
  16. 16. 1. Setup :- • PKG generates a prime p, the elliptic curve E/GF(p) with order n= #E/GF(p) • Generate a torsion group of prime order q • PKG selects a random master secret key “s” in range 0<s<q 2. Extract(Registration):- • Alice submits her identity to PKG • PKG convert its to a string and maps it to an element of GF(p) • Find a point (Q_ida) on the torsion group • Computes a point S_ida belongs to that group • PKG sends the alice her public and private key along with the public parameters Tate Pairing (Contd…)
  17. 17. 3. Encrypt:- • Alice computes Q_idb of Bob knowing public parameters p,q,P,Q and Bob’s identity. • Alice selects a random no “r” in range 0<r<q • Computes C1=[r]P and C2 = m.e(Q_idb, φ(q))r 4. Decrypt:- • Bob receives the ciphertext (C1, C2 ) • Computes m`= C2 * e(S_ida, φ(C1 )-1 • Check if m=m` or not Tate Pairing (Contd…)
  18. 18. Why these two Schemes are selected? • Weil pairing and Tate pairing both provide good functionality for use in cryptosystems • Fast implementations of these pairings • Uses Elliptic Curve Cryptography and a very small number of bits • Irrelevant factors and denominators are eliminated • Super singular curves are used • Uses random number generation to provide better security
  19. 19. Weil Pairing Vs. Tate Pairing • Tate pairing is faster than Weil pairing.. Weil pairing is er (p , p) = thus two application of Tate pairing. According to computation facts, Weil pairing takes twice the computational time than that of the Tate pairing. However Weil pairing usually takes more than twice the time to compute than that of the Tate pairing
  20. 20. • Tate pairing is used to reduce the discrete logarithm problem on certain elliptic curves to the discrete logarithm problem over finite field. Weil pairing of a point with itself is trivial as er (p , p) = 1 however, Tate pairing of a point with itself is not trivial as t (p , p) ≠ 1 • Tate pairing consumes less power and useful for Low-energy devices. For example : the TinyTate implemented for sensor networks require the system configuration :– 8-bit/7.3828-MHz ATmega128L microcontroller. However for Weil pairing the computation requires two Hash function evaluation, two Tate pairing computation which will gradually require higher system configuration. ( Weil Pairing vs. Tate Pairing in IBE systems by Ezra Brown, Eric Errthum, David Fu ) Weil Pairing Vs. Tate Pairing (Contd…)
  21. 21. Implementation Tools  Java  JPBC Library (Java Pairing Based Cryptography  PBC Library  GMP Library  MinGW (MSYS base system)  Netbeans Profiler
  22. 22. Performance Analysis Performance Analysis can be done in the following ways :  Memory Analysis  Runtime Analysis  Power Consumption, requirement of resources and cost of implementation  Security Parameters Among the above mentioned we will measure the performance on the basis of Memory and Runtime analysis.
  23. 23. Memory Analysis Weil Pairing Tate Pairing
  24. 24. Runtime Analysis Weil Pairing Tate Pairing
  25. 25. Future Scope Wireless Body Area Network comprised of low energy devices such as sensor nodes. Smart Phones are used to store the medical data gathered by the sensor nodes. In future these features can be implemented in android platform and then can be deployed in a small network of low energy sensor nodes.
  26. 26. Conclusions Through this presentation we have given an overview of the various Security issues in Wireless Body Area Networking and the possible solutions to overcome these issues. The solutions should be efficient in such a way that the low-energy sensor devices can be able for functioning the entire implementation. As well as Data security and Data confidentiality must be maintained and unauthorized accesses should be prohibited. For these the optimistic cryptographic and IBE schemes are invented such that Weil pairing and Tate pairing. And then to find the best scheme among the chosen options that is the Tate pairing depending upon various measurements.
  27. 27. References [1] A. Shamir, “Identity-based cryptosystems and signature schemes, “in Proc. Crypto ’84, Santa Barbara, CA, Aug, 1984, pages 47-53. [2] Dan Boneh, Matthew Franklin, “Identity-Based Encryption from the Weil pairing”, in SIAM J. of Computing, Vol. 32, No. 3, pages 586-615, 2003. [3] B S Adiga, Balamuralidhar P, Rajan M A, Ravishankara Shastry, Shivraj V L, "An Identity based Encryption using Elliptic Curve Cryptography for Secure M2M Communication", in TCS Innovation Labs, Bangalore, Karnataka, India, pp 68-75. [4] IEEE 5931464, Moncef Amara, Amar Siad, "ELLIPTIC CURVE CRYPTOGRAPHY AND ITS APPLICATIONS", in 7th International Workshop on Systems, Signal Processing and their Applications (WOSSPA), pages 247-250, 2011.