In this paper, we study the meet-in-the-middle attack against block cipher ARIA. We find some new 3-round and 4-round distinguishing properties of ARIA. Based on the 3-round distinguishing property, we can apply the meet-in-the-middle attack with up to 6 rounds for all versions of ARIA. Based on the 4-round distinguishing property, we can mount a successful attack on 8-round ARIA-256. Furthermo...

We consider the hash function proposals by Mridul et al. presented at FSE 2005. For the proposed 2n-bit compression functions it is proved that collision attacks require Ω(2) queries of the functions in question. In this note it is shown that with O(2n/3) queries one can distinguish the proposed compression functions from a randomly chosen 2n-bit function with very good probability. Finally we ...

WEP is a protocol for securing wireless networks. In the past years, many attacks on WEP have been published, totally breaking WEP’s security. This thesis summarizes all major attacks on WEP. Additionally a new attack, the PTW attack, is introduced, which was partially developed by the author of this document. Some advanced versions of the PTW attack which are more suiteable in certain environm...

We revisit the different approaches used in the literature to estimate the data complexity of distinguishing attacks on stream ciphers and analyze their inter-relationships. In the process, we formally argue which approach is applicable (or not applicable) in what scenario. To our knowledge, this is the first kind of such an exposition. We also perform a rigorous statistical analysis of the mes...

Is it possible that a block cipher apparently immune to classical differential cryptanalysis can be attacked considering a different operation on the message space? Recently Calderini and Sala showed how to effectively compute alternative operations on a vector space which can serve as message space for a block cipher such that the resulting structure is still a vector space. The latter were us...

Stream ciphers are cryptographic primitives that are used to ensure the privacy of a message that is sent over a digital communication channel. In this thesis we will present new cryptanalytic results for several stream ciphers. The thesis provides a general introduction to cryptology, explains the basic concepts, gives an overview of various cryptographic primitives and discusses a number of d...

In this paper, we present the first distinguishing attack on HMAC and NMAC based on MD5 without related keys, which distinguishes the HMAC/NMAC-MD5 from HMAC/NMAC with a random function. The attack needs 2 queries, with a success probability 0.87, while the previous distinguishing attack on HMAC-MD5 reduced to 33 rounds takes 2 messages with a success rate of 0.92. Furthermore, we give distingu...

Whirlpool is a hash function based on a block cipher that can be seen as a scaled up variant of the AES. The main difference is the (compared to AES) extremely conservative key schedule. In this work, we present a distinguishing attack on the full compression function of Whirlpool. We obtain this result by improving the rebound attack on reduced Whirlpool with two new techniques. First, the inb...

In this paper we construct several tools for manipulating pools of biases in the analysis of RC4. Then, we show that optimized strategies can break WEP based on 4000 packets by assuming that the first bytes of plaintext are known for each packet. We describe similar attacks for WPA. Firstly, we describe a distinguisher for WPA of complexity 243 and advantage 0.5 which uses 240 packets. Then, ba...

Common Scrambling Algorithm (CSA) has been used to encrypt european cable digital television signals since 1994. Although, the key size of CSA is small, up to now, there haven’t any effective crypto results which can break the algorithm totally. Based on the idea of slide resynchronization attack, a distinguishing attack which can distinguish the keystream of the Stream Cipher (SC) from a purel...