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1.
We describe new computationally secure protocols of
1-out-of-N oblivious transfer,
k-out-of-N oblivious transfer, and oblivious transfer with
adaptive queries.
The protocols are very efficient compared with solutions based on
generic two-party computation or on information-theoretic security.
The 1-out-of-N oblivious transfer protocol
requires only log N executions of a 1-out-of-2
oblivious transfer protocol. The
k-out-of-N protocol is considerably more efficient than k
repetitions of 1-out-of-N oblivious transfer, as is the
construction for
oblivious transfer with adaptive queries. The efficiency of the new
oblivious transfer
protocols makes them useful for many applications. A direct corollary of
the 1-out-of-N oblivious transfer protocol is an efficient transformation
of any Private Information Retrieval protocol to a Symmetric PIR protocol. 相似文献
2.
3.
非承诺加密机制是语义安全的,不能抵抗选择密文攻击.在non-erase模型的安全假设下,基于非承诺加密机制的不经意传输协议不能实现自适应攻击者UC(Universally Composable)安全的定义.利用可否认加密体制和可验证平滑投影哈希函数,提出了一个新的不经意传输协议,可否认加密体制通过陷门承诺的双陷门解密技术实现,新协议方案是可证明UC安全的,基于公共参考串模型,安全性可以归约为确定性复合剩余假设.新协议参与方能够处理指数空间的消息,计算效率得到改善,通过两次协议交互可以实现string-OT协议,与bit-OT协议相比单轮通信效率提高O(n)倍. 相似文献
4.
5.
The mobile agent is a fundamental building block of the mobile computing paradigm. In mobile agent security, oblivious transfer
(OT) from a trusted party can be used to protect the agent’s privacy and the hosts’ privacy. In this paper, we introduce a
new cryptographic primitive called Verifiable Distributed Oblivious Transfer (VDOT), which allows us to replace a single trusted party with a group of threshold trusted servers. The design of VDOT uses a novel
technique called consistency verification of encrypted secret shares. VDOT protects the privacy of both the sender and the receiver against malicious attacks of the servers. We also show the
design of a system to apply VDOT to protect the privacy of mobile agents. Our design partitions an agent into the general
portion and the security-sensitive portion. We also implement the key components of our system. As far as we know, this is
the first effort to implement a system that protects the privacy of mobile agents. Our preliminary evaluation shows that protecting
mobile agents not only is possible, but also can be implemented efficiently.
This work was supported in part by the DoD University Research Initiative (URI) program administered by the Office of Naval
Research under grant N00014-01-1-0795. Sheng Zhong was supported by ONR grant N00014-01-1-0795 and NSF grants ANI-0207399
and CCR-TC-0208972. Yang Richard Yang was supported in part by NSF grant ANI-0207399. A preliminary version of this paper
was presented at the DialM-POMC Joint Workshop on Foundations of Mobile Computing in 2003.
Sheng Zhong received his Ph.D. in computer science from Yale University in the year of 2004. He holds an assistant professor position
at SUNY Buffalo and is currently on leave for postdoctoral research at the Center for Discrete Mathematics and Theoretical
Computer Science (DIMACS). His research interests, on the practical side, are security and incentives in data mining, databases,
and wireless networks. On the theoretical side, he is interested in cryptography and game theory.
Yang Richard Yang is an Assistant Professor of Computer Science at Yale University. His research interests include computer networks, mobile
computing, wireless networking, sensor networks, and network security. He leads the LAboratory of Networked Systems (LANS)
at Yale. His recent awards include a Schlumberger Fellowship and a CAREER Award from the National Science Foundation. He received
his B.E. degree from Tsinghua University (1993), and his M.S. and Ph.D. degrees from the University of Texas at Austin (1998
and 2001). 相似文献
6.
We present an alternative to the controversial ``key-escrow' techniques for enabling law enforcement and national security
access to encrypted communications. Our proposal allows such access with probability p for each message, for a parameter p between 0 and 1 to be chosen (say, by Congress) to provide an appropriate balance between concerns for individual privacy, on the one hand,
and the need for such access by law enforcement and national security, on the other. (For example, with p=0.4 , a law-enforcement agency conducting an authorized wiretap which records 100 encrypted conversations would expect to be
able to decrypt (approximately) 40 of these conversations; the agency would not be able to decrypt the remaining 60 conversations
at all.) Our scheme is remarkably simple to implement, as it requires no prior escrowing of keys.
We implement translucent cryptography based on noninteractive oblivious transfer. Extending the schemes of Bellare and Micali
[2], who showed how to transfer a message with probability ?, we provide schemes for noninteractive fractional oblivious transfer,
which allow a message to be transmitted with any given probability p . Our protocol is based on the Diffie—Hellman assumption and uses just one El Gamal encryption (two exponentiations), regardless
of the value of the transfer probability p . This makes the implementation of translucent cryptography competitive, in efficiency of encryption, with current suggestions
for software key escrow.
Received 19 September 1996 and revised 1 November 1997 相似文献
7.
An efficient t‐out‐of‐n oblivious transfer for information security and privacy protection
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In t‐out‐of‐n oblivious transfer (OT), the receiver can only receive t messages out of n messages sent by the sender, and the sender has no idea about which ones have been received. Majority of the existence of previous efficient OT schemes require t calls of 1‐out‐of‐n OT to construct the t‐out‐of‐n OT. Its computational requirements and bandwidth consumption are quite demanding. On the basis of the elliptic curves cryptography, we propose a new t‐out‐of‐n OT protocol for private information retrieval in this article. It is more suitable for the smart cards or mobile units. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
Linking information reconciliation and privacy amplification 总被引:2,自引:0,他引:2
Information reconciliation allows two parties knowing correlated random variables, such as a noisy version of the partner's
random bit string, to agree on a shared string. Privacy amplification allows two parties sharing a partially secret string
about which an opponent has some partial information, to distill a shorter but almost completely secret key by communicating
only over an insecure channel, as long as an upper bound on the opponent’s knowledge about the string is known. The relation
between these two techniques has not been well understood. In particular, it is important to understand the effect of side-information,
obtained by the opponent through an initial reconciliation step, on the size of the secret key that can be distilled safely
by subsequent privacy amplification. The purpose of this paper is to provide the missing link between these techniques by
presenting bounds on the reduction of the Rényi entropy of a random variable induced by side-information. We show that, except
with negligible probability, each bit of side-information reduces the size of the key that can be safely distilled by at most
two bits. Moreover, in the important special case of side-information and raw key data generated by many independent repetitions
of a random experiment, each bit of side-information reduces the size of the secret key by only about one bit. The results
have applications in unconditionally secure key agreement protocols and in quantum cryptography.
This research was supported by the Swiss National Science Foundation. A preliminary version of this paper was presented at
Eurocrypt '94, May 9–12, Perugia, Italy. 相似文献