Vehicular Ad hoc Network (VANET), using IEEE 802.11p, forms an ad hoc network of vehicles with no additional infrastructure to provide security and convenience to the drivers. The network delivers the traffic related information to the vehicles commencing the inter-vehicular communication (IVC), considering driver's context awareness and sensitivity. Rather than moving in random fashion as in other ad hoc networks, vehicles move in an organized way. Since all the vehicles on road need to be equipped with message transmission capabilities, the realistic scenario of VANET is often canvassed. Secure routing and smooth operation are even more questionable. This research work aims to enhance security by integrating group signature with Non-transitive Proxy Re-encryption technique. Proxy re-encryption is a cryptographic technique which allows a third party to re-encrypt the message in such a way that it can decrypted by other authorized people as well, along with the person for which the message was originally sent. Non-transitiveness of the algorithm makes sure that proxy is not able to generate re-encryption key, rk A→C given rk A→B and rk B→C . This framework benefits the network in two possible ways: First, the message sent in group can be read by either member of the group or the groups which are allowed to read the message specifically using re-encryption technique. Second, even if the proxy is compromised, C cannot decrypt A's message if the re-encryption rights were given only for B.

Integrating group signature scheme with Non-transitive Proxy Re-encryption in VANET

La protection de la vie privee est un des enjeux majeurs de la societe moderne dans laquelle Internet est omnipotent. Dans cette these, nous etudions des techniques permettant de realiser un stockage dematerialise qui preserve la confidentialite des informations. Nous nous interessons ainsi a proteger les donnees stockees tout en permettant a leur proprietaire de les partager avec les personnes de son choix. Le serveur de re-chiffrement, une des primitives proposees par la cryptographie, est la solution que nous decidons de retenir.

Tout d'abord, nous donnons une definition d'un systeme de serveur de re-chiffrement qui regroupe tous les modeles classiques existants. Nous decrivons egalement les caracteristiques habituelles que peut presenter cette primitive ainsi que son modele de securite. Ensuite, nous nous concentrons plus particulierement sur certains schemas specifiques afin d'en ameliorer la securite. Nous presentons pour cela une methode qui transforme un schema sur contre une attaque a chiffre choisi rejouable en un schema sur contre une attaque a chiffre choisi. Nous etudions aussi les schemas fondes sur le chiffrement Hash ElGamal et proposons d'y apporter des modifications afin qu'ils atteignent une meilleure securite. Pour terminer et dans le but d'obtenir le stockage le plus fonctionnel possible, nous proposons deux nouveaux modeles. Le premier, que nous appelons serveur de re-chiffrement combine, permet d'obtenir une gestion dynamique des droits d'acces. Le second, que nous appelons serveur de re-chiffrement selectif, permet d'obtenir une gestion des droits d'acces plus fine que celle offerte par le serveur de re-chiffrement conditionnel.

https://hal.archives-ouvertes.fr/tel-01081377/document

Protocoles de re-chiffrement pour le stockage de données

SignCryption is the public-key cryptographic tool to guarantee various security paradigms by integrating digital signature and encryption. The traditional digital signature with encryption is very expensive as it requires massive computational overheads. Instead signcryption combines these two into one step, and overhead reduced is significantly observable. Proxy re-encryption is a technique in which a proxy enables a third person Chris to be able to decrypt a message which was sent by Alice for Bob. Instead of first signing and then encrypting, we are sending after just signcrypting the message into the network where proxy will re-encrypt it at the receiver end. We have used Bilinear Diffie-Hellman assumption, i.e., irreversible property of Diffie–Hellman assumption in bilinear groups with digital signatures to provide confidentiality, integrity, and non-repudiation. Later the result is evaluated using AVISPA, Automated Validation of Internet Security Protocols and Applications.

Signcrypting the Group Signature with Non-transitive Proxy Re-encryption in VANET

In proxy re-encrytpion (PRE) scheme, the message is sent by a delegator to a delegatee with a help of the trusted third party proxy without knowing the existing plaintext. PRE schemes are widely used in various applications. However, the standard PRE scheme has some proxy problems called private key generator (PKG) despotism problem. This means that PKG can make re-encryption key without permission from delegator. And also, if someone can attack PKG in a PRE scheme, they can decrypt both the original ciphertext and the re-encrypted ciphertext which means the key-escrow problem. A solution for these two problems is to use non-transferable PRE scheme. Non-transferable PRE scheme solved the above PKG despotism problem and key-escrow problem. We would like to introduce our PRE scheme with a new approach. In our scheme, there are three sub-processes, which are based on a non-transferable PRE scheme and group signature. Our scheme will provide the security for delegator i, delegatee j (who is in the same group with delegator i), and delegatee k (who is in a different group with delegator i).

Secure Non-transferable Proxy Re-encryption for Group Membership and Non-membership

A computer-implemented method, computer program product, and computing system is provided for encrypted document co-editing. In an implementation, a method may include receiving, at a first computing device, a first encrypted change set for a co-editable data object from a client, the first encrypted change set being encrypted by a first key. The method may include requesting a second key for re-encrypting the first encrypted change set. The method may include re-encrypting the first encrypted change set to generate a second encrypted change set using the second key.

System and method for encrypted document co-editing

Recently, proxy re-encryption scheme received much attention A proxy re-encryption used for divert ciphertext from one group to another without revealing underlying plaintext is proposed in this paper The scheme is bidirectional and any member can independently decrypt the ciphertext encrypted to its group The security of the proposed scheme is discussed and proofs are given to show that the scheme withstands chosen ciphertext attack in standard model

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Group-based proxy re-encryption scheme

In the ad hoc networks, group key management is one of the most important secure problems. We propose a hierarchical group key managementt scheme adapted to large groups according to network characteristics. The scheme put STR hierarchical tree structure into distributed sub-group management model effectively, and combine layer-based key management with cycle-based key management, in order to reduce the communication and computation cost greatly, and is of good attribute in expansibility and lange ad hoc networks.

The research of hierarchical group key management for ad hoc networks

Tree-based group key agreement protocol that allows group members to compute the group key based on their individual contributions can provide verifiable trust relationship between participants in ad-hoc networks. We discuss the principles and structural features of three tree-based group key agreement protocols, and compare the communication and computation that generated by each protocol when their members are adding, leaving, merging or breaking up. The analysis and comparison results show that each tree-based group key agreement protocol is applicable to corresponding ad-hoc network. We also provide reference and technical support for application of more complicated tree structure in ad-hoc networks.

Chun-bo Ma

Papers

Group-based proxy re-encryption scheme

The research of hierarchical group key management for ad hoc networks

Based on Tree Structure Group Key Management for Ad Hoc Networks