RC4 Stream Cipher Research Articles

RC4 stream cipher and possible attacks on WEP

In this paper we analyze and present some weaknesses and possible attacks on the RC4 stream cipher which were published in many journals. We review some advantages and disadvantages which come from several authors, as well as similarities and differences which can be observed in the published results. Also, we analyze the Key Scheduling Algorithm (KSA) which derives the initial state from a variable size key, and strengths and weaknesses of the RCS stream cipher. Using examples from other papers, we show that RC4 is completely insecure in a common mode of operation which is used in the widely deployed Wired Equivalent Privacy protocol (WEP, which is part of the 802.11 standard).

Cryptanalysis of Stream Ciphers from a New Aspect: How to Apply Key Collisions to Key Recovery Attack

In this paper, we propose two new attacks against stream cipher RC4 which can recover the secret key in different length with practical computational amount. However, we have to point out that the proposed attacks are performed under relatively strong related key models. The same as the usual related key models, the adversary can specify the key differentials without knowing the target key information. However, in our attacks, only the relation between two keystream outputs or the two final internal states are required for the attacker. In addition, we discover a statistical bias of RC4 which is the key point to one of the attacks. Besides the inappropriate usage during the WEP environment, RC4 is still considered to be secure with the proper setting, and we believe the result of this paper will add to the understanding of RC4 and how to use it correctly and safely.

Image Encription and Decription Based On Aes &Rc4

In the today world, security is required to transmit confidential information over the network Security is also demanding in wide range of applications. Cryptographic algorithms play a vital role in providing the data security against malicious attacks. But on the other hand, they consume significant amount of computing resources like CPU time, memory, encryption time etc. Normally, symmetric key algorithms (same key use For encryption and decryption) and asymmetric key algorithms (different key use for both encryption and decry piton) as they are very fast in nature. Symmetric algorithms are classified as block cipher (AES) and stream ciphers (RC4) algorithms. In this paper, we compare the AES (block cipher) algorithm with different modes of operation and RC4 (stream cipher) algorithm in terms of CPU time, encryption time, memory utilization and throughput at different settings like variable key size and variable data packet size and develop both block diagram.

A joint encryption/watermarking algorithm for verifying the reliability of medical images: Application to echographic images

In this paper we propose a joint encryption/watermarking algorithm for the purpose of protecting medical images. The proposed solution gives access to the outcomes of the image integrity and of its origins as its attachment to one patient even if the image is stored encrypted. In this study, the given solution combines the RC4 stream cipher and two substitutive watermarking modulations: the Least Significant Bit Method and the Quantization Index Modulation. If watermarking and encryption are conducted jointly at the protection stage, watermark extraction and decryption can be applied independently. Experimental results achieved on 8bits encoded echographic images illustrate the overall performances of the proposed scheme. At least, a capacity rate of 1 and 0.5bits of message per pixel of image can be embedded in the spatial and the encrypted domains respectively, with a peak signal to noise ratio greater than 49dB.

Generalized Classes of Weak Keys on RC4 Using Predictive State

Conventional class of weak keys on RC4 stream cipher is defined as a specific case that combinations of the first three bytes of secret key satisfy two relational equations. This paper expands and generalizes the classes of weak keys using generalized relational equations and special classes of the internal state (called predictive state). We derive the probability that generalized classes of weak keys leak the information of bytes of the secret key. Furthermore, we enumerate the generalized classes of weak keys and show that most of them leak more information of the secret key than Roos' one.

Generalized Analysis on Key Collisions of Stream Cipher RC4

The fact that the stream cipher RC4 can generate colliding key pairs with hamming distance one was first discovered by Matsui in FSE 2010. This kind of weakness demonstrates that two different secret keys have the same effect on the cipher's encryption and the corresponding decryption procedure. In this paper, we further investigate the property of RC4 key collisions and achieved the following results:1. We show that RC4 can generate colliding key pairs with various hamming distances, which cannot be generated by Matsui's pattern. We also give concrete examples of colliding key pairs with hamming distances greater than one.2. We formalize RC4 colliding key pairs into two large patterns, namely, Transitional pattern and Self-Absorbing pattern. All the currently known colliding key pairs can be categorized into either two patterns.3. We analyze both patterns and clarified the relations among the probability of key collision, key length and hamming distances which yield the colliding key pairs.4. We demonstrate the vulnerability of key collisions by showing collisions of RC4-Hash function proposed in INDOCRYPT 2006. Some concrete experimental results of RC4-Hash collision are also given in this paper.

Security in ad hoc networks and pervasive computing

Security in <i>ad hoc</i> networks and pervasive computing

Multiple Dimensional Fault Tolerant Schemes for Crypto Stream Ciphers

To enhance the security and reliability of thewidely-used stream ciphers, a 2-D and a 3-D mesh-knightAlgorithm Based Fault Tolerant (ABFT) schemes for streamciphers are developed which can be universally applied to RC4 and other stream ciphers. Based on the ready-made arithmetic unit in stream ciphers, the proposed 2-D ABFT scheme is able to detect and correct any simple error, and the 3-D mesh-knight ABFT scheme is capable of detecting andcorrecting up to three errors in a data matrix with liner computation and bandwidth overhead. The proposed schemes provide one-to-one mapping between data index and check sum group so that error can be located and recovered by easier logic and simple operations.

Wired equivalent privacy reinvestigated

Security is a strong requirement for effective deployment of business wireless communication applications. Therefore, many proposals dealt with security holes in Wired Equivalent Privacy protocol (WEP). In this paper, we analyze WEP security holes and we propose an improvement over WEP which achieves its security goals. Our premise is to permit deploying an efficient security mechanism on wireless networks. We introduce an efficient way by using shared session keys as the seed to the RC4 stream cipher. The shared session key can be calculated at the sender’s and the receiver’s end simultaneously by using the Triple Formula. The solution calculates the key without transmitting any part of it in open air unlike IV vector which eliminates the possibility of a key leak. Security analysis shows that the proposed scheme is strong against some well known attacks like Key Reuse, Authentication forging, Denial of Service, Brute force and Known plain text attack.

A lightweight secure data transmission protocol for resource constrained devices

AbstractIn this paper we present a lightweight but robust security protocol based on the forward and backward property of RC4 stream cipher. The proposed protocol offers data confidentiality, data authentication, data integrity, and data freshness with less operation and low overhead. Also, it allows data packets to be received in any arbitrary order and achieves semantic security. Furthermore, it eliminates the requirement of frequent key renewal to overcome a special limitation of the stream ciphers. Due to the competitive efficiency and lightweight, the proposed protocol is considerable to provide secure data transmission among resource constrained devices, where the communication nodes have limited power resources and computational capabilities. This protocol not only applies to one‐to‐one communications, but also works for the broadcasting and multicasting. Copyright © 2009 John Wiley &amp; Sons, Ltd.

An algorithm based mesh check-sum fault tolerant scheme for stream ciphers

To enhance the security and reliability of the widely-used stream ciphers, a novel mesh check-sum ABFT scheme for stream ciphers is developed. By utilising the ready-made arithmetic unit in stream ciphers, single and multiple errors can be detected and corrected in a cheap way. To meet different requirements in practical applications, 4D mesh check-sum ABFT scheme is proposed which can be applied to RC4 or other stream ciphers. The 2D mesh check-sum ABFT scheme is able to detect and correct single error with high efficiency. The 4D mesh check-sum ABFT scheme is capable of correcting up to three errors located randomly in an N-element matrix with acceptable computation and bandwidth overhead. The workload can be remarkably reduced when most communications are error-free. Our scheme also provides one-to-one mapping between index and check-sum, so that error can be located and recovered by easier logic and simpler operation.

A mesh check-sum ABFT scheme for stream ciphers

To enhance the security and reliability of the widely-used stream ciphers, a novel mesh check-sum ABFT scheme for stream ciphers is developed. By utilising the ready-made arithmetic unit in stream ciphers, single and multiple errors can be detected and corrected in a cheap way. To meet different requirements in practical applications, 4-D mesh check-sum ABFT scheme is proposed which can be applied to RC4 or other stream ciphers. The 2-D mesh check-sum ABFT scheme is able to detect and correct single error with high efficiency. The 4-D mesh check-sum ABFT scheme is capable of correcting up to three errors located randomly in an N-element matrix with acceptable computation and bandwidth overhead. The workload can be remarkably reduced when most communications are error-free. Our scheme also provides one-to-one mapping between index and check-sum, so that error can be located and recovered by easier logic and simpler operation.

DSP-128: Stream Cipher Based On Discrete Log Problem And Polynomial Arithmetic

DSP-128 is a new multithreaded stream cipher based on the intractability of the Discrete Logarithm Problem (DLP) with key size of 128-bit. The design of DSP-128 is divided into three stages: Initialization Stage, Keystream Generation Stage, and Encryption Stage. The design goal of DSP-128 is to come up with a secure stream cipher with good performance for data encryption. The experimental results show that the encryption rate of DSP-128 is one time slower (running on single processor) than the widely adapted stream cipher RC4, with a higher level of security against possible cryptanalysis attacks. However, because of its multithreaded nature, DSP-128 can take the speed up advantage of multi-core processor architectures which are available widely.

Attacks on the RC4 stream cipher

In this article we present some weaknesses in the RC4 cipher and their cryptographic applications. Especially we improve the attack described by Fluhrer, Mantin, Shamir (In: Selected Areas in Cryptography, 2001) in such a way, that it will work, if the weak keys described in that paper are avoided. A further attack will work even if the first 256 Byte of the output remain unused. Finally we show that variants of the RC4 algorithm like NGG and RC4A are also vulnerable by these techniques.

On non-negligible bias of the first output byte of RC4 towards the first three bytes of the secret key

In this paper, we show that the first byte of the keystream output of RC4 has non-negligible bias towards the sum of the first three bytes of the secret key. This result is based on our observation that the index, where the first byte of the keystream output is chosen from, is approximately twice more likely to be 2 than any other value. Our technique is further used to theoretically prove Roos's experimental observation (A class of weak keys in the RC4 stream cipher, 1995) related to weak keys.

Secured Flipped Scan-Chain Model for Crypto-Architecture

Scan chains are exploited to develop attacks on cryptographic hardware and steal intellectual properties from the chip. This paper proposes a secured strategy to test designs by inserting a certain number of inverters between randomly selected scan cells. The security of the scheme has been analyzed. Two detailed case studies of RC4 stream cipher and AES block cipher have been presented to show that the proposed strategy prevents existing scan-based attacks in the literature. The elegance of the scheme lies in its less hardware overhead.

Finding an internal state of RC4 stream cipher

The RC4 is a stream cipher widely deployed in software applications due to its simplicity and efficiency. The paper presents a cryptanalytic attack that employs the tree representation of this cipher and introduces an abstraction in the form of general conditions for managing the information about its internal state. In order to find the initial state, the tree of general conditions is searched applying the hill-climbing strategy. The complexity of this attack is lower than that of an exhaustive search. The attack is derived from a general cryptanalytic approach for a class of table-shuffling ciphers, whose next-state function permutes the table entries. Incorporating the general conditions in the existing backtracking algorithm, the estimated complexity of the cryptanalytic attack is decreased below the best published result but the RC4 still remains a quite secure cipher in practice.

A Scheme for Key Management on Alternate Temporal Key Hash

Wired equivalent privacy encryption of IEEE 802.11 standard is based on the RC4 stream cipher, but the weakness in its Initialization Vector (IV) derivation causes the Key Scheduling Algorithm (KSA) of RC4 to leak out the information about the secret key. It is shared among the particular participants in the Wireless LAN (WLAN). Housley et al. proposed an Alternate Temporal Key Hash (ATKH) to solve the weakness of the KSA; they defeated the particular IV may make the KSA to leak out the information about the shared secret key. However, the ATKH did not solve the key management in WLAN. Since a robust key management is a critical factor to prevent the eavesdropping from attackers. Therefore, in this paper, we shall propose a scheme to make key management feasible in their solution without changing the framework of the ATKH and the existing 802.11 standards.

A key recovery attack on the 802.11b wired equivalent privacy protocol (WEP)

In this paper, we present a practical key recovery attack on WEP, the link-layer security protocol for 802.11b wireless networks. The attack is based on a partial key exposure vulnerability in the RC4 stream cipher discovered by Fluhrer, Mantin, and Shamir. This paper describes how to apply this flaw to breaking WEP, our implementation of the attack, and optimizations that can be used to reduce the number of packets required for the attack. We conclude that the 802.11b WEP standard is completely insecure, and we provide recommendations on how this vulnerability could be mitigated and repaired.