Cryptosystems for hierarchical groups

Hossein Ghodosi, Josef Pieprzyk, Chris Charnes, Rei Safavi-Naini

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review

2 Citations (Scopus)


This paper addresses the problem of information protection in hierarchical groups. Higher level groups of participants can control the information flow (the decryption ability) to lower level groups. If a higher level group decides to allow a lower level group to read the message, it passes a go ahead ticket so the lower level group can decrypt the cryptogram and read the message. The formal model of top-down hierarchical cryptosystems is given. Two practical and efficient schemes are described. The first is based on the E1Gamal system. The second applies the RSA system. In proposed schemes the dealer publishes a public key such that an individual can use it to send an encrypted message to the (hierarchical) group. Publication of both the group public key and the encryption method does not reveal the decision of the group. The proposed cryptosystems are immune against conspiracy attack. The lack of verifiability of retrieved messages in threshold ElGamal cryptosystems is also discussed.

Original languageEnglish
Title of host publicationInformation Security and Privacy - 1st Australasian Conference, ACISP 1996, Proceedings
Place of PublicationBerlin; Heidelberg
PublisherSpringer, Springer Nature
Number of pages12
ISBN (Print)3540619917, 9783540619918
Publication statusPublished - 1996
Externally publishedYes
Event1st Australasian Conference on Information Security and Privacy, ACISP - 1996 - Wollongong, Australia
Duration: 24 Jun 199626 Jun 1996

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
ISSN (Print)03029743
ISSN (Electronic)16113349


Other1st Australasian Conference on Information Security and Privacy, ACISP - 1996


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