92 research outputs found
MV3: A new word based stream cipher using rapid mixing and revolving buffers
MV3 is a new word based stream cipher for encrypting long streams of data. A
direct adaptation of a byte based cipher such as RC4 into a 32- or 64-bit word
version will obviously need vast amounts of memory. This scaling issue
necessitates a look for new components and principles, as well as mathematical
analysis to justify their use. Our approach, like RC4's, is based on rapidly
mixing random walks on directed graphs (that is, walks which reach a random
state quickly, from any starting point). We begin with some well understood
walks, and then introduce nonlinearity in their steps in order to improve
security and show long term statistical correlations are negligible. To
minimize the short term correlations, as well as to deter attacks using
equations involving successive outputs, we provide a method for sequencing the
outputs derived from the walk using three revolving buffers. The cipher is fast
-- it runs at a speed of less than 5 cycles per byte on a Pentium IV processor.
A word based cipher needs to output more bits per step, which exposes more
correlations for attacks. Moreover we seek simplicity of construction and
transparent analysis. To meet these requirements, we use a larger state and
claim security corresponding to only a fraction of it. Our design is for an
adequately secure word-based cipher; our very preliminary estimate puts the
security close to exhaustive search for keys of size < 256 bits.Comment: 27 pages, shortened version will appear in "Topics in Cryptology -
CT-RSA 2007
Tornado Attack on RC4 with Applications to WEP & WPA
In this paper, we construct several tools for building and manipulating pools of biases in the analysis of RC4. We report extremely fast and optimized active and passive attacks against IEEE 802.11 wireless communication protocol WEP and a key recovery and a distinguishing attack against WPA. This was achieved through a huge amount of theoretical and experimental analysis (capturing WiFi packets), refinement and optimization of all the former known attacks and methodologies against RC4 stream cipher in WEP and WPA modes. We support all our claims on WEP by providing an implementation of this attack as a publicly available patch on Aircrack-ng. Our new attack improves its success probability drastically. Our active attack, based on ARP injection, requires 22500 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 27500 packets. This is much less than the number of packets Aircrack-ng requires in active mode (around 37500), which is a huge improvement. Deploying a similar theory, we also describe several attacks on WPA. Firstly, we describe a distinguisher for WPA with complexity 2^{42} and advantage 0.5 which uses 2^{42} packets. Then, based on several partial temporary key recovery attacks, we recover the full 128-bit temporary key of WPA by using 2^{42} packets. It works with complexity 2^{96}. So far, this is the best key recovery attack against WPA. We believe that our analysis brings on further insight to the security of RC4
Implementing and Evaluating Nonsingular Matrices Generators for the Hill Cipher
A Cifra de Hill (Hill Cipher) é um exemplo clássico de um sistema criptográfico com propriedades muito interessantes, nomeadamente a implementação dos conceitos de confusão e difusão apresentados por Shannon como propriedades essenciais para as cifras; no entanto, a sua forma básica é vulnerável a Known Plaintext Attacks (KPAs). [...]Hill Cipher is a classical example of a cryptosystem with interesting properties, namely that it implements the diffusion and confusion concepts coined by Shannon as essential properties for ciphers; nonetheless, its basic form is vulnerable to KPAs. [...
D.STVL.9 - Ongoing Research Areas in Symmetric Cryptography
This report gives a brief summary of some of the research trends in symmetric cryptography at the time of writing (2008). The following aspects of symmetric cryptography are investigated in this report: • the status of work with regards to different types of symmetric algorithms, including block ciphers, stream ciphers, hash functions and MAC algorithms (Section 1); • the algebraic attacks on symmetric primitives (Section 2); • the design criteria for symmetric ciphers (Section 3); • the provable properties of symmetric primitives (Section 4); • the major industrial needs in the area of symmetric cryptography (Section 5)
Cryptanalysis of MORUS
Item does not contain fulltextAdvances in Cryptology - ASIACRYPT 2018 - 24th International Conference on the Theory and Application of Cryptology and Information Security, Brisbane, QLD, Australia, December 2-
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