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Scalable Key Management for Secure Multicast Communication in the Mobile Environment. Jiannong Cao, Lin Liao, Guojun Wang Pervasive and Mobile Computing 2 (2006) 2007. 11. 8 Kim Pyung. Introduction. IP Multicast Saves a great deal of bandwidth
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Scalable Key Management for Secure Multicast Communication in the Mobile Environment Jiannong Cao, Lin Liao, Guojun Wang Pervasive and Mobile Computing 2 (2006) 2007. 11. 8 Kim Pyung
Introduction • IP Multicast • Saves a great deal of bandwidth • Needs group key management in a scalable and secure manner • Scalability • Under the mobile Internet environment • Frequent moving, joining and leaving, and the large size of a group • 1-affects-N phenomenon ( re-keying message, # of enc/decryption ) • Security • Backward / forward confidentiality Scalable Key Management for Secure Multicast Communication
System Model and Assumptions • Scalable and Hierarchical key management(SHKM) • S : multicast source • F: forwarding node, subgroup manager • CA : Centralized authority Scalable Key Management for Secure Multicast Communication
SHKM : Main idea • Hierarchy by subgroup priority ordering • Fi » Fj • Initiation : RSA algorithm • Randomly chosen TEKs by SGM • The parameters for derivation of the lower group’s TEK from CA • changing residue ej, related factor гij Scalable Key Management for Secure Multicast Communication
SHKM : Key Generation SGM Si chooses the TEK ki CA gets (PK, SK) by RSA PK : public key EPK(ki) DSK(ki) changing residue : ei = ki2 mod n ( n is secret ) if Sj » Si, related factor : гji= h(Zkj ei mod P) ki Si CA Scalable Key Management for Secure Multicast Communication
SHKM : Key Derivation TEK : kj requests for access Si parameters : ei, гji Ekj( ei, гji ) check Sj » Si ? Dkj ( ei, гji ) TEK of Si : ki = h(Zkj ei mod P) гji Sj CA Scalable Key Management for Secure Multicast Communication
SHKM : Key Modification • the relationship : Sj » Sl » Si key modification : kl kl* el* = ( kl*)2 mod n гjl* =h(Zkj el* mod P) kl* гli* = h(Zkl*ei mod P) ki Only direct successor and predecessor of Sl Scalable Key Management for Secure Multicast Communication
SHKM : Protocol analysis • Adding a new subgroup • A new subgroup Si into an existing multicast group • the changing residue ei, related factor г(CA) • No re-keying message and No re-generation of a new TEK for whole group Scalable • vs Key Graph ? • Backward confidentiality? Sh » Si (new) » Sj » Sk » Sl Scalable Key Management for Secure Multicast Communication
SHKM : Protocol analysis • Deletion of a subgroup • For the higher-priority subgroups • Delete the changing residue e, related factor г(CA) • No re-key message • For the lower-priority subgroups • New TEK for lower-priority subgroups • New changing residue e, related factor г(CA) • vs Centralized protocols ? - the cost transferred to CA Scalable Key Management for Secure Multicast Communication
SHKM : Protocol analysis • Leaving of subgroup members • Multiple leaving about h, (mi, mi+1, …, mi+h-1) in Sl • New TEK kl* for Sl new changing residue el(CA) • For the higher-priority subgroups • New related factor г(CA) • For the lower-priority subgroups • New TEK for lower-priority subgroups • New changing residue e, related factor г(CA) Scalable Key Management for Secure Multicast Communication
SHKM : Protocol analysis • Joining of a new subgroup member • New TEK kl* for Sl new changing residue el (CA) • For the higher-priority subgroups • New related factor г(CA) • For the lower-priority subgroups backward confidentiality • New related factor г(CA) Scalable Key Management for Secure Multicast Communication
SHKM : Protocol analysis • Migration of member between subgroups • First entry delayed re-keying + periodic (FEDRP) • A TEK timer table for members residing outside the subgroup • Leaving or timer expire “Reset” • A lower re-keying rate Scalable Key Management for Secure Multicast Communication
Attack Analysis • Continuous attack (in Lin’ scheme) ki is exposed Sj » Si гji = Zkj IDi mod P ki ki = Zkj IDi mod P гji ki*= Zkj IDi mod P гji* ki*=h( Zkj ei*mod P ) гji* • Sibling attack Sj » Si andSj » Sl h( Zkj ei* mod P ) = гji* ki h( Zkj el* mod P ) = гjl* kl Scalable Key Management for Secure Multicast Communication
Evaluation n : # of group users s : # of groups t : # of ave successors m : # of ave dir-successors r : related factor computation e : changing residue computation Scalable Key Management for Secure Multicast Communication
Conclusions • No re-keying messages, but some reporting messages • Reduced enc/dec cost compared with decentralized transferred to CA • The defense of malicious attacks Scalable Key Management for Secure Multicast Communication