Proxy re-encryption (PRE) allows a proxy to convert a ciphertext encrypted under one key into an encryption of the same message under another key. The main idea is to place as little trust and reveal as little information to the proxy as necessary to allow it to perform its translations. At the very least, the proxy should not be able to learn the keys of the participants or the content of the ...

In this work we revisit and formally study the notion of proxy cryptography. Intuitively, various proxy functions allow two cooperating parties F (the “FBI”) and P (the “proxy”) to duplicate the functionality available to the third party U (the “user”), without being able to perform this functionality on their own (without cooperation). The concept is closely related to the notion of threshold ...

In a multi-proxy multi-signature scheme, there is a group of original signers who delegate their signing rights to another group of persons called proxy group. Most of the known cryptography schemes used bilinear pairings, the computation cost of the which is much higher than that of the exponentiation in a RSA group. In this paper, we propose a certificateless multi-proxy multi-signature schem...

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 another. Our schemes are compatible with curr...

We consider the possibility that single-source multicast (SSM) will become a universal multicast service, enabling large-scale distribution of content from a few well-known sources to a general audience. Operating under this assumption, we explore the problem of building the traditional IP model of any-source multicast on top of SSM. Toward this end, we design an SSM proxy service that allows a...

In this paper, we introduce a new functionality for proxy re-encryption (PRE) that we call re-encryption verifiability. In a PRE scheme with re-encryption verifiability (which we simply call verifiable PRE, or VPRE), a receiver of a re-encrypted ciphertext can verify whether the received ciphertext is correctly transformed from an original ciphertext by a proxy, and thus can detect illegal acti...

As people in modern societies are busier than any human era and computer network has profound impact on how people work and live through fast and convenient information exchange, people need more help from each other to accomplish more work via network connections in limited period of time. Therefore, privilege delegation mechanism has become a necessary service in modern enterprises and organi...

Recent studies have shown that caching data at the proxy server can improve the user response time for web document retrieval. However, a single cache proxy has a limited cache space, thus the amount of data that can be cached is limited. In this paper, we organize the distributed proxy servers into a group of peer-to-peer cache proxies. By exploiting the aggregate cache space and computing pow...

In a proxy signature scheme, a potential signer delegates his signing capability to a proxy entity, who signs a message on behalf of the original signer. All the proposals of proxy signature schemes made until now have been based on Schnorr's signature scheme. Threshold versions of these schemes have also been proposed, in which the power of the proxy signer is distributed among a group of play...