Collision attack

About: Collision attack is a research topic. Over the lifetime, 1093 publications have been published within this topic receiving 28389 citations.

Multi-way hash join effectiveness

Abstract: In database systems most join algorithms are binary and will only operate on two inputs at a time. In order to join more than two input relations a database system will use the results of a binary join of two of the inputs in a second join. This way any number of input relations can be combined into a single output. There is additional cost to having multiple joins as the results of each intermediate join must be cached and processed. Recent research into joins on more than two inputs, called multi-way joins, has shown that the intermediate partitioning steps of a traditional hash join based query plan can be avoided. This decreases the amount of disk based input and output (I/Os) that the join query will require which is desirable since disk I/O is one of the slowest parts of a join. This thesis studies the advantages and disadvantages of implementing and using different multi-way join algorithms and their relative performance compared to traditional hash joins. Specifically, this work compares dynamic hash join with three multi-way join algorithms, Hash Teams, Generalized Hash Teams and SHARP. The results of the experiments show that in some limited cases these multi-way hash joins can provide a significant advantage over the traditional hash join but in many cases they can perform worse. Since the cases where these multi-way joins have better performance is so limited and their algorithms are much more complex, it does not make sense to implement Hash Teams or Generalized Hash Teams in production database management systems. SHARP provides enough of a performance advantage that it makes sense to implement it in a database system used for data warehousing.

Collision Attack on 4-branch, Type-2 GFN based Hash Functions using Sliced Biclique Cryptanalysis Technique.

Abstract: In this work, we apply the sliced biclique cryptanalysis technique to show 8-round collision attack on a hash function H based on 4-branch, Type-2 Generalized Feistel Network (Type-2 GFN). This attack is generic and works on 4-branch, Type-2 GFN with any parameters including the block size, type of round function, the number of S-boxes in each round and the number of SP layers inside the round function. We rst construct a 8-round distinguisher on 4-branch, Type-2 GFN and then use this distinguisher to launch 8-round collision attack on compression functions based on Matyas-Meyer-Oseas (MMO) and Miyaguchi-Preneel (MP) modes. The complexity of the attack on 128bit compression function is 2. The attack can be directly translated to collision attack on MP and MMO based hash functions and pseudocollision attack on Davies-Meyer (DM) based hash functions. When the round function F is instantiated with double SP layer, we show the rst 8 round collision attack on 4-branch, Type-2 GFN with double SP layer based compression function. The previous best attack on this structure was a 6-round near collision attack shown by Sasaki at Indocrypt'12. His attack cannot be used to generate full collisions on 6-rounds and hence our result can be regarded the best so far in literature on this structure.

Apparatus and Method for Protecting Power Collision Attack on Elliptic Curve Cryptography

Abstract: The present invention relates to an apparatus and a method which allow an elliptic curve cryptography (ECC) encryption algorithm to respond to a power collision attack, by configuring a Lopez-Dahab Montgomery ladder (LDML) algorithm so as to be safe against a side channel analysis. Responding to the power collision attack on the ECC encryption algorithm is achieved by applying a register address bit randomizing technique and a random projection coordinate system, additionally using one register, and consistently randomizing a register address for loading and storing data or fixing the register address, to remove correlation between the register address and a key bit. An apparatus for responding to the power collision attack on the ECC encryption algorithm includes: a plain text and secret key input unit; a register address random value generation unit; a point random value generation unit; an initial calculation unit; a point adding and doubling unit; a final calculation unit; and an encrypted text output unit.

Privacy preserving secret key extraction protocol for multi-authority attribute-based encryption techniques in cloud computing

Abstract: In the existing privacy-preserving multi-authority attribute-based encryption (MA-ABE) techniques, the users receive their secret keys from multiple authorities, where each authority maintains a different set of user attributes with major control established by a central authority (CA), who manages all the attribute-related activities (causes collision attack). Also, as the secret key is derived from user sensitive attributes, the authorities may collect and analyse the user attributes to recognise a user's identity which leads to compromised key attack and insider attack. In order to solve these issues, we propose a privacy preserving secret key extraction (PPSE) protocol, which stores user attributes in fuzzy attribute set format over hash index. This enables easier extraction of the secret key from outsourced user attributes and it eliminates the need for the involvement of a central authority for user attribute management. We implemented PPSE using Charm crypto (Akinyele et al., 2013) and the experimental results show that our scheme provides higher levels of user access provision with improved security and privacy.

NMACA: a novel methodology for message authentication code algorithms

Abstract: For objects stored in long-term digital archives, checking the integrity of the information stored is a prime necessity in the field of secure storage systems. Objects in a digital archive may include documents, images, databases, ..., etc. In a long-term archive those objects could be transferred in many various ways. In many cases, users are required to verify the authentication of the archived information. The goal of all authentication algorithmic techniques is to verify that information in the archive is authentic and has not been unintentionally or maliciously altered. Integrity checks not only detect malicious attacks but also identify data corrupted information. Keyed hash functions whose specific purpose is message authentication are called message authentication code (MAC) algorithms. Many iterated MACs can be described as iterated hash functions. In this case, the MAC key is fed as an input to the compression function, and be involved in the compression function f at every stage. Recently, powerful new attacks on hash functions such MD5 and SHA-1, among others, suggest introducing more secure hash functions. In this paper, we propose a new family of algorithms that use an input MAC key to the compression function in permuting the order of message words and shifting operation in the compression function. The new technique can be working in conjunction with a wide range of message authentication algorithm. Using MD5 algorithm as a model, a new MD5-MAC algorithm is presented. The proposed algorithm uses the MAC key in building the hash functions by defining the order for accessing source words and defining the number of bit positions for left shifts.