@inproceedings{82d3973b0d6c4c98b9786de9265274c4,
title = "Protection of data and delegated keys in digital distribution",
abstract = "A cryptography is quite effective in protecting digital information from unauthorized access. But if a receiver of information is determined after the encryption of the information, e.g. a posted encrypted news is withdrawn by an arbitrary user in open networks, we need an additional mechanism for converting the encrypted information into a form accessible only to an admissible user. Even though such a transformation is done by the consecutive execution of decryption of a ciphertext and re-encryption of a recovered plaintext, an intermediary plaintext may be stolen during the re-encryption. In this paper we examine secure digital distribution systems, information storage system and information provider system, in which encrypted information is directly transformed into a ciphertext of an admissible user. We show that the technique of a proxy cryptosystem is useful for establishing these distribution systems. Proposed protocols can be constructed base on the EIGamal cryptosystem or the RSA cryptosystem. Meanwhile, a blind decryption protocol provides privacy protection with respect to the selection of a ciphertext to be decrypted. In terms of digital distribution it also provides a secure information delivery. An information provider system using a blind decryption protocol possesses a problem such that a decrypting person computes exponentiation for a message freely selected by a requesting person. For such an oracle problem, a solution is known with use of a transformable signature. In this paper we show another measure prohibiting the abuse of the blind decryption protocol.",
author = "Masahiro Mambo and Eiji Okamoto and Kouichi Sakurai",
year = "1997",
month = jan,
day = "1",
doi = "10.1007/BFb0027934",
language = "English",
isbn = "3540632328",
series = "Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)",
publisher = "Springer Verlag",
pages = "271--282",
editor = "Josef Pieprzyk and Vijay Varadharajan and Yi Mu",
booktitle = "Information Security and Privacy -2nd Australasian Conference, ACISP 1997, Proceedings",
address = "Germany",
note = "2nd Australasian Conference on Information Security and Privacy, ACISP 1997 ; Conference date: 07-07-1997 Through 09-07-1997",
}