1. Security in mobile ad-hoc networks using soft encryption and trust-based multi-path routing Authors: Prayag Narula, Sanjay Kumar Dhurandher, Sudip Misra, and Isaac Woungang. Sources: Computer Communications, article in press. Reporter: Chun-Ta Li ( 李俊達 )

2. 2 22 Outline  Motivation  Proposed routing strategy  Comments

3. 3 Motivation  Message security using trust-based multi-path routing in MANETs Multi-path routing (on-demand routing)  divide the message into different parts Soft encryption  eliminate the need of Key Distribution Center and key transfer  using the message itself for encryption Trustworthiness  trusted node is allowed to feature in more paths

4. 4 Proposed routing strategy  Trust level (-1 to 4) 4 : complete trust 0 : initial trust -1: complete distrust  Multi-path routing neighboring nodes track and listen leave node destination source

5. 5 Proposed routing strategy (cont.)  On-demand routing protocol S D ABC EFG HIJ R_REQ R_REP The R_REP message is appended with the trust level of the successor node by the node

6. 6 Proposed routing strategy (cont.)  Message encryption A 4n-bits message is divided into four parts of n bits each (denote these parts by a, b, c and d) a’ = a XOR c b’ = b XOR d c’ = c XOR b d’ = d XOR a XOR b

7. 7 Proposed routing strategy (cont.)  Message decryption A 4n-bits message is divided into four parts of n bits each (denote these parts by a, b, c and d) a = b’ XOR d’ b = a’ XOR b’ XOR c’ XOR d’ c = a’ XOR b’ XOR d’ d = a’ XOR c’ XOR d’

8. 8 Proposed routing strategy (cont.)  Trust defined strategy 4 : those nodes can be given the right to read the full message 3 : those nodes can be sure of finding 2 n possible messages of which one would be correct 2 : those nodes can be sure of finding 2 n * 2 n possible messages 1 : those nodes can be sure of finding 2 n * 2 n * 2 n possible messages

9. 9 Proposed routing strategy (cont.)  Algorithm to select secure routes

10. 10 Proposed routing strategy (cont.)  Example (four parts) S D 111 11 13 1 2 2 2 a’ b’ c’ d’

11. 11 Comments  A node with normal trust level may easily read the partial message and the property of confidentiality would not be achieved. S D 111 11 13 1 2 2 2 a’ b’ c’ d’ {a, c} {a}{a}

12. 12 Comments (cont.)  A node with normal trust level may easily read the full message and the property of confidentiality would not be achieved. b’ c’ d’ b’d’XOR a a c’ d’ c c XOR c’b b XOR b’ d d’ c’ b’ c’ a’ {a, c} a’ {d}{d} Ø

13. 13 Comments (cont.)  If a, b, c, and d are encrypted by means of the following equations a’ = a XOR b XOR c b’ = a XOR b XOR d c’ = a XOR c XOR d d’ = b XOR c XOR d b’ d’ c’ b’ c’ a’ {b}{b} {c}{c} {a}{a} b’ d’ {d}{d} c’

14. 14 Comments (cont.)  Fabrication attack  Lack of mutual authentication between source and destination node  Payment system  Nuglets (virtual currency) S D ABC EFG HIJ R_REQ R_REP Nuglets (SA) Nuglets (SB)Nuglets (SC) Nuglets (SH) Nuglets (SI)Nuglets (SJ) Nuglets (SE)Nuglets (SF)Nuglets (SG)