非对称双线性对下的基于身份的加密方案

基于身份的加密是一种直接以用户的身份作为公钥的加密方案。自提出以来,利用双线性对实现基于身份的加密方案的案例已经有很多,但是这些方案大都是采用对称的双线性对,即要求作为映射输入的两个群相同。这无疑缩小了映射中所选取的椭圆曲线的范围,将在一种更一般的条件下,即在非对称双线性对下,基于判定性双线性Diffe-Hellman（BDHE）难解问题在标准模型下构造出一种新型的基于身份的加密方案,并证明其在标准模型下具有不可区分的选择身份的选择明文（IND-sID-CPA）安全性。     

椭圆曲线加密体制分析

论文对常见的椭圆曲线加密体制进行了分析,制的优点和缺点,并分析了每种加密体制的时间复杂性。应用中选择椭圆曲线加密体制时参考。给出了E1Gamal型、ECMV和ECIES三种椭圆曲线加密体针对分析结果,提出了对每种加密体制的使用建议,供实际     

基于椭圆曲线的代理数字签名

现有的代理数字签名方案都是基于离散对数问题和大数因子分解问题的方案.本文我们将代理签名的思想应用于椭圆曲线数字签名,提出了一种新的基于椭圆曲线离散对数问题的代理签名方案,并对方案的复杂性和安全性进行了分析.在对方案的安全性分析中,我们还提出了两类椭圆曲线上的困难问题.新方案不仅推广和丰富了代理签名的研究成果,而且也扩展了椭圆曲线密码的密码功能,为信息安全问题的解决提供了新的密码学方法.     

A hybrid chaotic system and cyclic elliptic curve for image encryption

Recently, several image encryption schemes based on chaotic maps have been proposed. Nevertheless, most of them hinder the system performance, security, and suffer from the small key space problem. This paper presents an efficient hybrid image encryption scheme based on a cyclic elliptic curve and chaotic system that overcomes these disadvantages. The new scheme generates an initial keystream based on chaotic system and an external secret key of 256-bit in a feedback manner. Then, the generated keystream are mixed with key sequences derived from the cyclic elliptic curve points. Thorough encryption performance and security analysis ascertains efficacy of the proposed encryption scheme.     

Efficient Linear Homomorphic Encryption from LWE Over Rings

As the basis for secure public-key encryption under various cases, the learning with errors (LWE) problem has proved to be versatile for encryption schemes. Unfortunately, it tends not to be efficient enough for practical applications. For improving the efficiency issues and quickening the practical applications of the lattice-based public-key cryptosystems, an efficient homomorphic encryption scheme is presented in this paper, which is based on the learning with errors over rings (R-LWE) assumption, and its security is reducible to the hardness of the shortest vector problem in the worst case on ideal lattices. Furthermore, the scheme possesses homomorphism feature that encryption operations are consistent with message operations. The security analysis shows that the proposed encryption scheme is secure against chosen-plaintext attacks in the standard model. At the same time, the efficiency analysis and simulation results indicate that the scheme is much more efficient than previous lattice-based cryptosystems.     

一种基于Z/nZ上椭圆曲线的公钥密码算法

本文在 Ｋ Ｍ Ｏ Ｖ 算法［１］的基础上作了改动,提出了一种 Ｚ／ｎ Ｚ 上椭圆曲线公钥密码算法,ｎ是两个大安全素数之积,算法安全性基于整数因子分解难题,与 Ｒ Ｓ Ａ 体制相似,能抵卸一些对 Ｒ Ｓ Ａ 算法的攻击,不足之处在于不能证明其安全性是否等价于因子分解问题。算法加解密过程都很简洁,且在加密过程中引入随机数,实现概率加密。同时给出了数字签名和身份认证方案。     

Attribute-based fully homomorphic encryption scheme over rings

The fully homomorphic encryption has important applications in the area of data security and privacy security of cloud computing,but the size of secret keys and ciphertext in most of current homomorphic encryption schemes were too large,which restricted its practical.To improve these drawbacks,a recoding scheme and a attribute-based encryption scheme based on learning with errors problem over rings were provided,then a attribute-based fully homomorphic encryption was constructed.The new scheme overcame the above mentioned drawbacks,because it did't need public key certificate,meanwhile,it can achieve the fine-grained access control to the ciphertext.Compared with similar results,proposed method decreases the size of keys and ciphertext greatly.     

Ad hoc网络中基于环Zn上椭圆曲线和RSA的密钥管理

探讨了ad hoc网络密钥管理问题,首次利用环Zn上椭圆曲线所构成的陷门离散对数的同态性质,结合Shamir秘密分享方案,提出了一种新的适用于ad hoc网络的密钥管理方案.在该方案中,新加入的成员向组内成员提供环Zn上的椭圆曲线加密体制,并保密相应的陷门.利用该加密体制的同态性,参与密钥分发的成员将关于新成员的子密钥加密后依次相加,新成员得到最后的和,然后解密;为防止攻击者来自于组内成员,在每次子密钥加密中都加入了混合因子.新方案具有很好的安全性,破解该方案的难度不低于破解RSA.     

Paillier''s Trapdoor Function Hides up to O ( n ) Bits

At EuroCrypt '99 Paillier proposed a new encryption scheme based on higher residuosity classes. The new scheme was proven to be one-way under the assumption that computing N -residuosity classes in Z _N2 ^* is hard. Similarly the scheme can be proven to be semantically secure under a much stronger decisional assumption: given w ∈ Z _N2 ^* it is impossible to decide if w is an N -residue or not. In this paper we examine the bit security of Paillier's scheme. We prove that if computing residuosity classes is hard, then given a random w it is impossible to predict the least significant bit of its class significantly better than at random. This immediately yields a way to obtain semantic security without relying on the decisional assumption (at the cost of several invocations of Paillier's original function). In order to improve efficiency we then turn to the problem of simultaneous security of many bits. We prove that Paillier's scheme hides n-b (up to O(n) ) bits if one assumes that computing the class c of a random w remains hard even when we are told that c<2 ^b . We thoroughly examine the security of this stronger version of the intractability of the class problem. An important theoretical implication of our result is the construction of the first trapdoor function that hides super-logarithmically (up to O(n) ) many bits. We generalize our techniques to provide sufficient conditions for a trapdoor function to have this property.     

Identity-based key agreement and encryption for wireless sensor networks

1 Introduction WSN has received considerable attention during last decade [1?4] (see, for example, the proceedings of the ACM and IEEE Workshops on WSN). It has wide variety of applications, including military sensing and tracking, environment and securit…     

基于椭圆曲线的若干密码方案

由椭圆曲线上的点构成的代数系统可以为密码学提供多种应用方案。本文描述了基于椭圆曲线的数据加密体制、密钥交换方案和数字签名方案。上述方案的安全性建立在离散对数问题上,目前已知的攻击椭圆曲线对数问题的算法仍然是指数时间。本文还分析了安全椭圆曲线应满足的条件,给出了安全椭圆曲线密码系统的构造方法。     

Constructive and destructive facets of Weil descent on elliptic curves

In this paper we look in detail at the curves which arise in the method of Galbraith and Smart for producing curves in the Weil restriction of an elliptic curve over a finite field of characteristic 2 of composite degree. We explain how this method can be used to construct hyperelliptic cryptosystems which could be as secure as cryptosystems based on the original elliptic curve. On the other hand, we show that the same technique may provide a way of attacking the original elliptic curve cryptosystem using recent advances in the study of the discrete logarithm problem on hyperelliptic curves. We examine the resulting higher genus curves in some detail and propose an additional check on elliptic curve systems defined over fields of characteristic 2 so as to make them immune from the methods in this paper. Received January 2000 and revised December 2000 Online publication 29 August 2001     

一种NTRU格上基于身份全同态加密体制设计

全同态加密可以用来解决云计算环境中的隐私保护问题,然而现有体制具有系统参数大、效率低的缺点.针对现有攻击技术,首先设计了一种高效的NTRU格上的基于身份公钥加密体制,无需借助额外的安全性假设,具有更高的安全性和更小的系统参数.之后,基于近似特征向量技术,构造了一种高效的全同态加密转化方式.通过将以上两种方法结合,给出了一种高效的基于身份全同态加密体制.和现有体制相比,除了不需要计算密钥、实现了真正意义上的基于身份特性以外,还减小了密钥、密文尺寸,提高了计算和传输效率.     

利用RLWE构造基于身份的全同态加密体制

全同态加密为云计算中数据全生命周期隐私保护等难题的解决都提供了新的思路.公钥尺寸较大是现有全同态加密体制普遍存在的问题.本文将基于身份加密的思想和全同态加密体制相结合,利用环上容错学习问题（Ring Learning With Errors,RLWE）,其中将环的参数m扩展到任意正整数,提出了一种基于身份的全同态加密体制.体制以用户身份标识作为公钥,在计算效率和密钥管理方面都具有优势,安全性在随机喻示模型下可规约为判定性RLWE问题难解性假设.     

Audio Encryption Using Ameliorated ElGamal Public Key Encryption Over Finite Field

Performing encryption using ElGamal public key encryption over finite field requires imbedding of message which is represented by integers. These integers are to be imbedded to a coordinate location that satisfy the elliptic curve equation using Koblitz imbedding technique. In doing so, data expansion takes place as each integer have to be represented as a coordinate. Recommended elliptic curves have large modulo prime value, so for every small integer representation of a message, the expansion in cipher text is massive. The above factors hinders the usage of ElGamal method for large data size encryption. In the ameliorated version, every coordinates in the elliptic curve equation is applicable for performing encryption operation. The typical Koblitz imbedding technique to specific coordinates satisfying the elliptic curve equation can be avoided. Data expansion trouble is taken care by using base conversion operation with multiple audio data. Simulation results and performance comparison with other public key cryptosystem signify that the proposed method is suitable for audio encryption operation.

     

Software Implementation of Elliptic Curve Encryption over Binary Field

The mathematical theory for elliptic curve encryption based on optimal normal basis(ONB) over F_2~m is introduced.Then an elliptic curve cryptography(ECC) based encryption scheme isanalyzed and designed.The mechanism for key exchange based on Diffie-Hellman is described in detailsfor further applications.Based on these theoretic foundations,the software based on ECC is developedand an application is provided.The software is characterized by excellent security as well as highefficiency.     

Identity-based multisignature and aggregate signature schemes from m-torsion groups

I. Introduction A multisignature allows any subgroup of a given group of potential signers to jointly sign a message such that a verifier is convinced that each member of the subgroup participated in signing. An aggre-gate signature, recently proposed by Boneh et al.[1], however, is a scheme that allows n members of a given group of potential signers to sign n different messages and all these signatures can be aggregated into a single signature. This single signature will convince the verifie…     

Selecting Cryptographic Key Sizes

In this article we offer guidelines for the determination of key sizes for symmetric cryptosystems, RSA, and discrete logarithm-based cryptosystems both over finite fields and over groups of elliptic curves over prime fields. Our recommendations are based on a set of explicitly formulated parameter settings, combined with existing data points about the cryptosystems. Received September 1999 and revised February 2001 Online publication 14 August 2001     

椭圆曲线型多重数字签名算法研究

介绍了数字签名技术的概念,通过对椭圆曲线数字签名算法的分析,提出了一个基于椭圆曲线数字签名算法的多重数字签名方案,其安全性是基于求解椭圆曲线离散对数问题的,可在保持与RSA或DSA体制同样的安全性的前提下缩短密钥长度,降低了通信成本,提高了网络信息的安全性。     

Two-Key Triple Encryption

In this paper we consider multiple encryption schemes built from conventional cryptosystems such as DES. The existing schemes are either vulnerable to variants of meet-in-the-middle attacks, i.e., they do not provide security corresponding to the full key length used or there is no proof that the schemes are as secure as the underlying cipher. We propose a variant of two-key triple encryption with a new method of generating three keys from two. Our scheme is not vulnerable to the meet-in-the-middle attack and, under an appropriate assumption, we can show that our scheme is at least about as hard to break as the underlying block cipher. Received 22 June 1995 and revised 11 October 1996