Wi-Fi Security Analysis

AbstractIn recent years, a significant increasing in development of Wireless networks is noticed; they become an entire part of the Internet and demonstrate effectiveness in handling communication for reduced public LAN and military applications. This is mainly due to their mobility and low cost solutions; nevertheless, they are also prone to several attacks related to data integrity, Deni of Service and eavesdropping. This paper discusses wireless security protocols, their limitations and weakness. We present also an overview of the FMS (Fluhrer, Mantin, Shamir), a recovery key attack and demonstrate its effectiveness in reducing the average number of intercept packets based on a well choice of IV (initialization vectors). Some comparative experiments on ciphertext-only attacks were performed in order to study the efficiency of such technique and underline encountered difficulties

RC4 Encryption-A Literature Survey

AbstractA chronological survey demonstrating the cryptanalysis of RC4 stream cipher is presented in this paper. We have summarized the various weaknesses of RC4 algorithm followed by the recently proposed enhancements available in the literature. It is established that innovative research efforts are required to develop secure RC4 algorithm, which can remove the weaknesses of RC4, such as biased bytes, key collisions, and key recovery attacks on WPA. These flaws in RC4 are still offering an open challenge for developers. Hence our chronological survey corroborates the fact that even though researchers are working on RC4 stream cipher since last two decades, it still offers a plethora of research issues. The attraction of community towards RC4 is still alive

On Reconstruction of RC4 Keys from Internal States

In this work key recovery algorithms from the known internal states of RC4 are investigated. In particular, we propose a bit-by-bit approach to recover the key by starting from LSB's of the key bytes and ending with their MSB's

Dumb Crypto in Smart Grids: Practical Cryptanalysis of the Open Smart Grid Protocol

This paper analyses the cryptography used in the Open Smart Grid Protocol (OSGP). The authenticated encryption (AE) scheme deployed by OSGP is a non-standard composition of RC4 and a home-brewed MAC, the ``OMA digest\u27\u27. We present several practical key-recovery attacks against the OMA digest. The first and basic variant can achieve this with a mere $13$ queries to an OMA digest oracle and negligible time complexity. A more sophisticated version breaks the OMA digest with only $4$ queries and a time complexity of about $2^{25}$ simple operations. A different approach only requires one arbitrary valid plaintext-tag pair, and recovers the key in an average of $144$ \emph{message verification} queries, or one ciphertext-tag pair and $168$ \emph{ciphertext verification} queries. Since the encryption key is derived from the key used by the OMA digest, our attacks break both confidentiality and authenticity of OSGP

New Form of Permutation Bias and Secret Key Leakage in Keystream Bytes of RC4

Consider the permutation $S$ in RC4. Roos pointed out in 1995 that after the Key Scheduling Algorithm (KSA) of RC4, each of the initial bytes of the permutation, i.e., $S[y]$ for small values of $y$, is biased towards some linear combination of the secret key bytes. In this paper, for the first time we show that the bias can be observed in $S[S[y]]$ too. Based on this new form of permutation bias after the KSA and other related results, a complete framework is presented to show that many keystream output bytes of RC4 are significantly biased towards several linear combinations of the secret key bytes. The results do not assume any condition on the secret key. We find new biases in the initial as well as in the 256-th and 257-th keystream output bytes. For the first time biases at such later stages are discovered without any knowledge of the secret key bytes. We also identify that these biases propagate further, once the information for the index $j$ is revealed

Dependence in IV-related bytes of RC4 key enhances vulnerabilities in WPA

The first three bytes of the RC4 key in WPA are public as they are derived from the public parameter IV, and this derivation leads to a strong mutual dependence between the first two bytes of the RC4 key. In this paper, we provide a disciplined study of RC4 biases resulting specifically in such a scenario. Motivated by the work of AlFardan et al. (2013), we first prove the interesting sawtooth distribution of the first byte in WPA and the similar nature for the biases in the initial keystream bytes towards zero. As we note, this sawtooth characteristics of these biases surface due to the dependence of the first two bytes of the RC4 key in WPA, both derived from the same byte of the IV. Our result on the nature of the first keystream byte provides a significantly improved distinguisher for RC4 used in WPA than what had been presented by Sepehrdad et al. (2011-12). Further, we revisit the correlation of initial keystream bytes in WPA to the first three bytes of the RC4 key. As these bytes are known from the IV, one can obtain new as well as significantly improved biases in WPA than the absolute biases exploited earlier by AlFardan et al. or Isobe et al. We notice that the correlations of the keystream bytes with publicly known IV values of WPA potentially strengthen the practical plaintext recovery attack on the protocol

Structural Weaknesses in the Open Smart Grid Protocol

The Open Smart Grid Protocol (OSGP) is currently deployed in various countries in large-scale Smart Metering projects. The protocol was developed by the OSGP Alliance and published as a standard by the European Telecommunications Standards Institute (ETSI). We identify several security issues in the OSG Protocol, primarily the use of a weak digest function and the way the protocol utilizes the RC4 algorithm for encryption. A straight-forward oracle attack triggers the leakage of key material of the digest function. We outline how an attacker can make use of the simple protocol structure to send maliciously altered messages with valid authentication tags to the meters

Smashing WEP in A Passive Attack

In this paper, we report extremely fast and optimised active and passive attacks against the old IEEE 802.11 wireless communication protocol WEP. This was achieved through a huge amount of theoretical and experimental analysis (capturing WiFi packets), refinement and optimisation of all the former known attacks and methodologies against RC4 stream cipher in WEP mode. We support all our claims by providing an implementation of this attack as a publicly available patch on Aircrack-ng. Our new attacks improve its success probability drastically. We adapt our theoretical analysis in Eurocrypt 2011 to real-world scenarios and we perform a slight adjustment to match the empirical observations. Our active attack, based on ARP injection, requires 22 500 packets to gain success probability of 50% against a 104-bit WEP key, using Aircrack-ng in non-interactive mode. It runs in less than 5 seconds on an off-the-shelf PC. Using the same number of packets, Aicrack-ng yields around 3% success rate. Furthermore, we describe very fast passive only attacks by just eavesdropping TCP/IPv4 packets in a WiFi communication. Our passive attack requires 27 500 packets. This is much less than the number of packets Aircrack-ng requires in active mode (around 37 500), which is a huge improvement.We believe that our analysis brings on further insight to the security of RC4

Plaintext Recovery Attacks Against WPA/TKIP

We conduct an analysis of the RC4 algorithm as it is used in the IEEE WPA/TKIP wireless standard. In that standard, RC4 keys are computed on a per-frame basis, with specific key bytes being set to known values that depend on 2 bytes of the WPA frame counter (called the TSC). We observe very large, TSC-dependent biases in the RC4 keystream when the algorithm is keyed according to the WPA specification. These biases permit us to mount an effective statistical, plaintext-recovering attack in the situation where the same plaintext is encrypted in many different frames (the so-called ``broadcast attack\u27\u27 setting). We assess the practical impact of these attacks on WPA/TKIP