Xor based hash functions book pdf

Cryptographic hash functions play an important central role in cryptology. Hashing is faster than encryption library code for hash functions widely available can easily replace one hash function with another. The preimage resistance and second preimage resistance properties are identical to the above apre and asec notions, respectively. Xor based hash functions, which compute each set index bit as the exclusiveor of a subset of the address bits. Next, we provide another novel algorithm to defeat additive checksums. Four basic properties are typically desired of cryptographic hash functions. Hashing for message authentication purdue college of engineering. The attack is based on a novel technique to break the pairwise relationship between the. Part of the lecture notes in computer science book series lncs, volume 4964. H is a hash function such as sha1, eis a symmetrickey encryption algorithm, \jj denotes simple. The sum can be weaker than each part cryptology eprint archive. Cryptography based on hash function blake 32 in vlsi gibi sunny.

Alia school of computer sciences, universiti sains malaysia, penang, malaysia summary cryptographic hash function has been used extensively in many cryptographic protocols. Hash functions, also referred to as message digests, do not use a key, but instead create a largely unique and fixedlength hash value, commonly referred to as a hash, based on the original message, something along the same lines as a fingerprint. When the keystream is generated by a pseudorandom number generator, the result is a stream cipher. The md6 hash function free download as powerpoint presentation. Cryptanalysis of a class of cryptographic hash functions cryptology.

Since circulant hash is an almost xoruniversal hash function for balanced inputoutput, it may not be a perfect substitute for h 3 and. Specifically, the section of postquantum cryptography deals with different quantum key distribution methods and mathematical based solutions, such as the bb84 protocol, lattice based cryptography, multivariate based cryptography, hash based signatures and code based cryptography. It is a mathematical algorithm that maps data of arbitrary size often called the message to a bit string of a fixed size the hash value, hash, or message digest and is a oneway function, that is, a function which is practically infeasible to invert. This is a list of hash functions, including cyclic redundancy checks, checksum functions, and. When you want to find somebodys phone number, you search the book based on the name field. Authentication code mac and the overall hash function as a keyed hash function. Design of new xorbased hash functions for cache memories core. A short universal hash function from bit rotation, and applications. I hx x mod n is a hash function for integer keys i hx. We survey theory and applications of cryptographic hash functions, such as md5 and sha1, especially their resistance to collisionfinding attacks. In this paper, we design new xorbased hash functions, which compute each set index bit as xor of a subset of the bits in the address by using the concepts of rank and null space. Rfid mutual authentication protocols using key exchange. In this paper, we bring out the importance of hash functions, its various structures, design techniques, attacks and the progressive recent development in this field. We survey theory and applications of cryptographic hash functions, such as md5 and sha1, especially their resistance to collision.

Any slight change to the message will change the hash. Incremental multiset hash functions and their application. But we can do better by using hash functions as follows. Suppose i have two hash functions, of which neither or only one is collision resistant, and i want to create a new hash function by taking the bitwise exclusive or xor of the results of those two functions. We will discuss such applications of hash functions in greater detail in section 15. New hash function based on chaos theory cha1 mahmoud maqableh, azman bin samsudin and mohammad a. In this paper, we design new xorbased hash functions, which compute each set index bit as xor of a subset of the bits in the address by using the concepts of. Cryptographic hash functions are used to achieve a number of security objectives. A dictionary is a set of strings and we can define a hash function as follows. Implementation is based on paritypreserving bit operations xor and. A hash function is typically based on an internal compression function f that works on fixedsize input blocks mi sort of like a chained block cipher produces a hash value for each fixedsize block based on 1 its content and 2 hash value for the previous block avalanche effect. The xor cipher is often used in computer malware to make reverse engineering more difficult. A tabulation based hash function maps a key into d derived characters indexing random values in tables that are then combined with bitwise xor operations to give the hash.

Selected topics in cryptography solved exam problems. Handbook of applied cryptography chapter 9 hash functions and data integrity pdf available d stinson. A cryptographic hash function chf is a hash function that is suitable for use in cryptography. The xor encryption method should be used by itself. Or just use a hash function that does claim to be a prf when used this way. The scheme in figure 1c is a publickey encryption version of the scheme shown in figure 1b. Haifa structure, extensibleoutput functions xofs design. In a damgardmerkle hash with a linearxor checksum, each bit of the checksum is a. In a subsequent ballot round, landon curt noll improved on their algorithm. You can be sure that you will get a good general understanding of algorithms if you spend time reading the book, solving problems. Just like a hammer is good if you want to hit on nails, not so much if you want to feed a baby a baby bottle is better for that one main usage of hash functions is to get a digest which represents a given piece of data.

The size of the hash value will be equal to the block length. The hashcode of the message is encrypted with the senders private key. Constructing optimal xorfunctions to minimize cache. The compression property requires that messages of any length be hashed to a nite domain. Finding a good hash function it is difficult to find a perfect hash function, that is a function that has no collisions. The hash function is based on xoring bits of the key. Ron rivests proposal for a modern cryptographically secure hash function. Thorup and zhang 2004 presented dwise independent tabulation based hash classes that use linear maps over finite fields to map a key, considered as a vector a,b, to. Learning what hash functions are and how mac functions are used.

Alan kaminsky rochester institute of technology department of computer science february 17, 2004 oneway hash functions the secure hash algorithm family double hashing message authentication codes digital signatures encryption and. When implementing an xor based hash function, it is extremely important to understand what patterns are mapped conflictfree and how a hash function. Hash functions and hash tables a hash function h maps keys of a given type to integers in a. In this paper we propose a new universal hash function based on bit rotation. Incremental multiset hash functions and their application to memory integrity checking dwaine clarke. Request pdf xorbased hash functions bank conflicts can severely reduce the bandwidth of an interleaved multibank memory and conflict misses increase. Is it possible for this new function to be collision resistant. Intermediate state hash function compression function diamond structure generic attack. Of course, the book is also suitable for anybody else interested in competitive programming. This is effectively the same as using method 1 with a key of x 0s. Suppose we need to store a dictionary in a hash table. To apply the constructed hash functions to the skewedassociative cache, we. To solve out this problem, this paper suggests mutual authentication rfid protocols that can guarantee safety from spoofing and retransfer attack and also reduce the number of comparative operations in the backend database, with the use of hash functions, xor.

Linearxor and additive checksums dont protect damgardmerkle. Assuming the hash is supposed to be x bytes long, break the message into blocks of x bytes. In this paper, we analyze the xor operator in the hash based flow selection function at the highspeed links, and prove that bit xor operator can increase the uniformity of distribution. Using this algorithm, we set an upper bound on the conflict reduction achievable with xor functions. Design of new xorbased hash functions for cache memories. These are conflictfree hash functions which are of different types according to whether m is even or odd. Cryptography based on hash function blake 32 in vlsi. Eliminating cache conflict misses through xorbased.

Whats wrong with xor encryption with hash and an iterated. Design of new xorbased hash functions for cache memories core reader. A boolen hash function is given that takes a hexadecimal key as input and returns the hash for that key hash can be only 0 or 1. The md6 hash function 64 bit computing cryptography. Hash functions can be designed to give best worstcase performance, good performance under high table loading factors, and in special cases, perfect collisionless mapping of keys into hash codes.