Plaintext Pairs Research Articles

Side-channel cryptographic attacks using pseudo-boolean optimization

Symmetric block ciphers, such as the Advanced Encryption Standard (AES), are deterministic algorithms which transform plaintexts to ciphertexts using a secret key. These ciphers are designed such that it is computationally very difficult to recover the secret key if only pairs of plaintexts and ciphertexts are provided to the attacker. Constraint solvers have recently been suggested as a way of recovering the secret keys of symmetric block ciphers. To carry out such an attack, the attacker provides the solver with a set of equations describing the mathematical relationship between a known plaintext and a known ciphertext, and then attempts to solve for the unknown secret key. This approach is known to be intractable against AES unless side-channel data --- information leaked from the cryptographic device due to its internal physical structure --- is introduced into the equation set. A significant challenge in writing equations representing side-channel data is measurement noise. In this work we show how casting the problem as a pseudo-Boolean optimization instance provides an efficient and effective way of tolerating this noise. We describe a theoretical analysis, connecting the measurement signal-to-noise ratio and the tolerable set size of a non-optimizing solver with the success probability. We then conduct an extensive performance evaluation, comparing two optimizing variants for dealing with measurement noise to a non-optimizing method. Our best optimizing method provides a successful attack on the AES cipher which requires surprisingly little side-channel data and works in reasonable computation time. We also make available a set of AES cryptanalysis instances and provide some practical feedback on our experience of using open-source constraint solvers.

A Lightweight Encryption Scheme Combined with Trust Management for Privacy-Preserving in Body Sensor Networks

With the pervasiveness of smart phones and the advance of wireless body sensor network (BSN), mobile Healthcare (m-Healthcare), which extends the operation of Healthcare provider into a pervasive environment for better health monitoring, has attracted considerable interest recently. However, the flourish of m-Healthcare still faces many challenges including information security and privacy preservation. In this paper, we propose a secure and privacy-preserving framework combining with multilevel trust management. In our scheme, smart phone resources including computing power and energy can be opportunistically gathered to process the computing-intensive PHI (personal health information) during m-Healthcare emergency with minimal privacy disclosure. In specific, to leverage the PHI privacy disclosure and the high reliability of PHI process and transmission in m-Healthcare emergency, we introduce an efficient lightweight encryption for those users whose trust level is low, which is based on mix cipher algorithms and pair of plain text and cipher texts, and allow a medical user to decide who can participate in the opportunistic computing to assist in processing his overwhelming PHI data. Detailed security analysis and simulations show that the proposed framework can efficiently achieve user-centric privacy protection in m-Healthcare system.

Security analysis of Modified Rivest Scheme

Abstract The Modified Rivest Scheme (MRS) is an additive homomorphic scheme recently used in many applications which demands third party processing of encrypted data. The present study carries out a comprehensive security analysis of MRS. We work out an attack from the category of known plaintext, chosen plaintext, chosen ciphertext where the adversary is having with him the pair of plaintext and its corresponding ciphertext. It is demonstrated that in such a scenario the adversary can compute the private key of the legitimate node causing threat to the security of the entire system. The novelty of the present study lies in the fact that any attack from the above mentioned category could be mounted on MRS (which is not being attacked so far), irrespective of the fact whether the modulus of the underlying MRS is kept private or made public.

Overview of Linear Cryptanalysis on S-DES and Block Ciphers using Hill Cipher Method

In this paper presents the Linear Cryptanalysis on S-DES and Symmetric Block Ciphers Using Hill Cipher Method. As a vehicle of demonstration of this concept, choose simple yet representative block ciphers such as computationally tractable versions of S-DES, for the studies. The attack presented in this paper is applicable to block structure independently of the key scheduling. The attack needs distinct known plaintexts which are a more realistic attack model in comparison with impossible differential cryptanalysis which uses chosen plaintext pairs. Moreover, linear cryptanalysis on simplified data encryption standard performed simulations on a small variant block and present the experimental results on the theoretical model of the multidimensional linear cryptanalysis using Hill Cipher method. General Terms Simplified Data Encryption Standard, Symmetric Block Cipher.

Differential Fault Analysis for Round-Reduced AES by Fault Injection

This paper presents a practical differential fault analysis method for the faulty Advanced Encryption Standard (AES) with a reduced round by means of a semi-invasive fault injection. To verify our proposal, we implement the AES software on the ATmega128 microcontroller as recommended in the standard document FIPS 197. We reduce the number of rounds using a laser beam injection in the experiment. To deduce the initial round key, we perform an exhaustive search for possible key bytes associated with faulty ciphertexts. Based on the simulation result, our proposal extracts the AES 128-bit secret key in less than 10 hours with 10 pairs of plaintext and faulty ciphertext.

General Impossible Differential Attack on 7-Round AES

Impossible differential attack (IDA) uses impossible differential characteristics extracted from enough plaintext pairs to retrieve subkeys of the first and the last several rounds of AES. In this paper, a general IDA on 7-round AES is proposed. Such attack takes the number of all-zero columns of the 7th and the 6th round as parameters (α, β). And a trade-off relation between the number of plaintexts and times of encryptions in the process of the attack is derived, which makes only some values of (α, β) allowed in the attack for different key length.

Impossible Differential Cryptanalysis of CLEFIA-128/192/256

PDF HTML阅读 XML下载 导出引用 引用提醒 CLEFIA-128/192/256的不可能差分分析 DOI: 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: Supported by the National Natural Science Foundation of China under Grant No.60525201 (国家自然科学基金); the National Basic Research Program of China under Grant No.2007CB807902 (国家重点基础研究发展计划(973)) Impossible Differential Cryptanalysis of CLEFIA-128/192/256 Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:对分组密码算法CLEFIA进行不可能差分分析.CLEFIA算法是索尼公司在2007年快速软件加密大会(FSE)上提出来的.结合新发现和新技巧,可有效过滤错误密钥,从而将算法设计者在评估报告中给出的对11圈CLEFIA-192/256的攻击扩展到11圈CLEFIA-128/192/256,复杂度为2103.1次加密和2103.1个明文.通过对明文附加更多限制条件,给出对12圈CLEFIA-128/192/256的攻击,复杂度为2119.1次加密和2119.1个明文.而且,引入一种新的生日筛法以降低预计算的时间复杂度.此外,指出并改正了Tsunoo等人对12圈CLEFIA的攻击中复杂度计算方面的错误. Abstract:An improved impossible differential attack on the block cipher CLEFIA is presented. CLEFIA was proposed by Sony Corporation at FSE 2007. Combining some observations with new tricks, the wrong keys are filtered out more efficiently, and the original impossible differential attack on 11-round CLEFIA-192/256 published by the designers, is extended to CLEFIA-128/192/256, with about 2103.1 encryptions and 2103.1 chosen plaintexts. By putting more constraint conditions on plaintext pairs, we present an attack on 12-round CLEFIA for all three key lengths with 2119.1 encryptions and 2119.1 chosen plaintexts. Moreover, a birthday sieve method is introduced to decrease the complexity of the precomputation. And an error about the time complexity evaluation in Tsunoo et al.’s attack on 12-round CLEFIA is pointed out and corrected. 参考文献 相似文献 引证文献

New Weakness in the Key-Scheduling Algorithm of RC4

In a key scheduling algorithm (KSA) of stream ciphers, a secret key is expanded into a large initial state. An internal state reconstruction method is known as a general attack against stream ciphers; it recovers the initial state from a given pair of plaintext and ciphertext more efficiently than exhaustive key search. If the method succeeds, then it is desirable that the inverse of KSA is infeasible in order to avoid the leakage of the secret key information. This paper shows that it is easy to compute a secret key from an initial state of RC4. We propose a method to recover an l-bit secret key from only the first l bits of the initial state of RC4 using linear equations with the time complexity less than that of one execution of KSA. It can recover the secret keys of which number is 2103.6 when the size of the secret key is 128bits. That is, the 128-bit secret key can be recovered with a high probability when the first 128bits of the initial state are determined using the internal state reconstruction method.

A simple power analysis attack against the key schedule of the Camellia block cipher

This paper presents a simple power analysis attack against the key schedule of Camellia. The attack works for the smart card environment which leaks the Hamming weight of data being processed, making use of the Hamming weight to deduce all key bits. It is shown that determining the cipher key given accurate power analysis data is very fast and does not require any pair of plaintext and ciphertext.