Giuseppe Ateniese

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We introduce a model for <i>provable data possession</i> (PDP) that allows a client that has stored data at an untrusted server to verify that the server possesses the original data without retrieving it. The model generates probabilistic proofs of possession by sampling random sets of blocks from the server, which drastically reduces I/O costs. The client(More)
In 1998, Blaze, Bleumer, and Strauss (BBS) proposed an application called <i>atomic proxy re-encryption</i>, in which a semitrusted proxy converts a ciphertext for Alice into a ciphertext for Bob <i>without</i> seeing the underlying plaintext. We predict that fast and secure re-encryption will become increasingly popular as a method for managing encrypted(More)
A group signature scheme allows a group member to sign messages anonymously on behalf of the group. However, in the case of a dispute, the identity of a signature’s originator can be revealed (only) by a designated entity. The interactive counterparts of group signatures are identity escrow schemes or group identification scheme with revocable anonymity.(More)
Storage outsourcing is a rising trend which prompts a number of interesting security issues, many of which have been extensively investigated in the past. However, Provable Data Possession (PDP) is a topic that has only recently appeared in the research literature. The main issue is how to frequently, efficiently and securely verify that a storage server is(More)
A visual cryptography scheme for a set P of n participants is a method to encode a secret image SI into n shadow images called shares, where each participant in P receives one share. Certain quali ed subsets of participants can \visually" recover the secret image, but other, forbidden, sets of participants have no information (in an information-theoretic(More)
In a proxy re-encryption scheme a semi-trusted proxy converts a ciphertext for Alice into a ciphertext for Bob without seeing the underlying plaintext. A number of solutions have been proposed in the public-key setting. In this paper, we address the problem of Identity-Based proxy re-encryption, where ciphertexts are transformed from one identity to(More)
We introduce a model for <i>provable data possession</i> (PDP) that can be used for remote data checking: A client that has stored data at an untrusted server can verify that the server possesses the original data without retrieving it. The model generates probabilistic proofs of possession by sampling random sets of blocks from the server, which(More)
An extended visual cryptography scheme, EVCS for short, for an access structure (? Qual ; ? Forb) on a set of n participants, is a technique to encode n images in such a way that when we stack together the transparencies associated to participants in any set X 2 ? Qual we get the secret message with no trace of the original images, but any X 2 ? Forb has no(More)
Many modern computing environments involve dynamic peer groups. Distributed simulation, multi-user games, conferencing applications and replicated servers are just a few examples. Given the openness of today’s networks, communication among peers (group members) must be secure and, at the same time, efficient. This paper studies the problem of authenticated(More)
Many storage systems rely on replication to increase the availability and durability of data on untrusted storage systems. At present, such storage systems provide no strong evidence that multiple copies of the data are actually stored. Storage servers can collude to make it look like they are storing many copies of the data, whereas in reality they only(More)