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Topic: Cryptographic hash function

Related Topics

Hash collision

Hash function

HMAC

Tiger (hash)

MD5

MD2

MD4

Asymmetric key algorithm

RSA

Checksum

Birthday attack

Cryptography

Cyclic redundancy check

Inequality of arithmetic and geometric means

Weak key

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	MD5z.com :: Encryption and Security Digest
		Hash functions that are truly random with uniform output (including most cryptographic hash functions) are good in that, on average, only one or two probes will be needed (depending on the load factor).
		Aside from minimizing collisions, the hash function for a hash table should also be fast relative to the cost of retrieving a record in the table, as the goal of minimizing collisions is minimizing the time needed to retrieve a desired record.
		The hash function is computed for the data at the sender, and the value of this hash is sent with the data.
	www.md5z.com (1334 words)

	Pluto Scarab â” Hash Functions (Site not responding. Last check: 2007-10-19)
		Hash functions are functions that map a bit vector to another bit vector, usually shorter than the original vector and usually of fixed length for a particular function.
		Hash functions play an important role in encryption because it is their properties that cause the encrypted data to be unreadable and the original data to be unrecoverable from the encrypted data without the decryption key.
		If a hash function is to be used for cryptography or for fast table lookup where the nature of the keys is unknown, the one-way property is a requirement.
	bretm.home.comcast.net /hash (841 words)

	Q94: What is a Hash Function? (Site not responding. Last check: 2007-10-19)
		A hash function H is a transformation that takes a variable-size input m and returns a fixed-size string, which is called the hash value h (that is, h = H(m)).
		A hash function H is said to be one-way if it is hard to invert, where "hard to invert" means that given a hash value h, it is computationally infeasible to find some input x such that H(x) = h.
		Since hash functions are generally faster than digital signature algorithms, it is typical to compute the digital signature to some document by computing the signature on the document's hash value, which is small compared to the document itself.
	www.x5.net /faqs/crypto/q94.html (311 words)

	Hash Functions - CryptoDox
		It is often also called a "message digest." Hash functions are used for digital signatures such as RSA and DSA, but also for the construction of MACs (message authentication codes), the protection of passwords, and for the derivation of independent secret keys from a single master key.
		Cryptographic hash functions are an essential building block for applications that require data integrity, such as detectors of computer viruses, Internet security (for example PGP or IPSEC), and the security of electronic commerce and banking.
		A hash function must be a one-way function, which means that finding an input corresponding to a given output string is difficult: Even an opponent who wants to spend a significant amount of money, say $10 million, will have a negligible success probability.
	www.cryptodox.com /index.php?title=Hash_Functions (247 words)

	Cryptographic hash function - Wikipedia, the free encyclopedia
		In cryptography, a cryptographic hash function is a hash function with certain additional security properties to make it suitable for use as a primitive in various information security applications, such as authentication and message integrity.
		A typical use of a cryptographic hash would be as follows: Alice poses to Bob a tough math problem and claims she has solved it.
		The SHA hash functions are a series of functions developed by the NSA: SHA, also known as SHA-0, SHA-1 and four flavours of a function known as SHA-2.
	en.wikipedia.org /wiki/Cryptographic_hash_function (1659 words)

	RSA Security - 2.1.6 What is a hash function?
		A hash function H is a transformation that takes an input m and returns a fixed-size string, which is called the hash value h (that is, h = H(m)).
		Hash functions with just this property have a variety of general computational uses, but when employed in cryptography, the hash functions are usually chosen to have some additional properties.
		Since hash functions are generally faster than encryption or digital signature algorithms, it is typical to compute the digital signature or integrity check to some document by applying cryptographic processing to the document's hash value, which is small compared to the document itself.
	www.rsasecurity.com /rsalabs/node.asp?id=2176 (525 words)

	.:: General Purpose Hash Function Algorithms - By Arash Partow ::.
		When algorithms which contain hash functions are analyzed it is generally assumed that hash functions have a complexity of O(1), that is why look-ups for data in a hash-table are said to be of O(1) complexity, where as look-ups of data in maps (Red-Black Trees) are said to be of O(logn) complexity.
		Cryptographic hash functions are used to hash user's passwords and have the hash of the passwords stored on a system rather than having the password itself stored.
		It is a simple hash function using a strange set of possible seeds which all constitute a pattern of 31....31...31 etc, it seems to be very similar to the DJB hash function.
	www.partow.net /programming/hashfunctions (1801 words)

	Glossary - OWASP
		A function that takes an input string of arbitrary length and produces a fixed- size output — where it is unfeasible to find two inputs that map to the same output, and it is unfeasible to learn anything about the input from the output.
		A construction for turning a block cipher into a cryptographic hash function, where the output length is twice the block size of the cipher.
		Strong collision resistance is a property that a hash function may have (and a good cryptographic hash function will have), characterized by it being computationally unfeasible to find two arbitrary inputs that yield the same output.
	www.owasp.org /index.php/Category:Glossary (6680 words)

	RSA Security - RSAES-OAEP Dictionary
		cryptographic hash function A deterministic function H mapping bit strings of arbitrary length to bit strings of a fixed length such that H is collision-resistant and one-way.
		For example, the output from OAEP is a function of the input and a random seed.
		If the random oracle is supposed to simulate a deterministic function (such as a mask generation function), then it must output the same element every time it is given a certain input.
	www.rsasecurity.com /rsalabs/node.asp?id=2148 (1997 words)

	SSH - Support - Cryptography A-Z - Introduction to Cryptography - Cryptographic Hash Functions
		Cryptographic hash functions are used in various contexts, for example, to compute the message digest when making a digital signature.
		A hash function compresses the bits of a message to a fixed-size hash value in a way that distributes the possible messages evenly among the possible hash values.
		The most famous cryptographic hash functions are those of the MD family: MD4, MD5, SHA-1, and RipeMD-160.
	www.ssh.com /support/cryptography/introduction/hash.html (290 words)

	Hash Integrity - monotone documentation
		Some proponents of a competing, proprietary version control system have suggested, in a usenix paper, that the use of a cryptographic hash function such as sha1 as an identifier for a version is unacceptably unsafe.
		The fanciful val1 hash presented in the paper does not have such a property — flipping its first bit when all the rest are zero causes no change to any of the 160 output bits — and is completely unsuited for use as a cryptographic hash, regardless of the general shape of its probability distribution.
		Therefore the vulnerability is not that the hash might suddenly cease to address benign blocks well, but merely that additional security precautions might become a requirement to ensure that blocks are benign, rather than malicious.
	www.venge.net /monotone/docs/Hash-Integrity.html (961 words)

	Background on cryptographic
		Hash functions are sometimes called "fingerprint functions" because they can be used to create a unique "fingerprint" of a digital file.
		The hash functions were envisioned as a kind of cryptographic compression system-a way to take a large file and crunch it down to a short string of letters and numbers.
		The fundamental requirement of a good hash function is that it should be impossible to predict the fingerprint of a file without actually going to the effort of computing that fingerprint -there must be no short-cuts.
	www.pfarrell.com /music/slimserver/hash.html (2724 words)

	rfc2104
		The cryptographic strength of HMAC depends on the properties of the underlying hash function.
		Definition of HMAC The definition of HMAC requires a cryptographic hash function, which we denote by H, and a secret key K. We assume H to be a cryptographic hash function where data is hashed by iterating a basic compression function on blocks of data.
		In particular, it uses the function H with the pre-defined initial value IV (a fixed value specified by each iterative hash function to initialize its compression function).
	ietfreport.isoc.org /idref/rfc2104 (2246 words)

	MD4 - Encyclopedia, History, Geography and Biography
		It implements a cryptographic hash function for use in message integrity checks.
		In August 2004, researchers reported generating collisions in MD4 using "hand calculation" [1], alongside attacks on later hash function designs in the MD4/MD5/SHA/RIPEMD family.
		The 128-bit (16-byte) MD4 hashes (also termed message digests) are typically represented as 32-digit hexadecimal numbers.
	www.arikah.net /encyclopedia/MD4 (397 words)

	RFC 2104 (rfc2104) - HMAC: Keyed-Hashing for Message Authentication
		The cryptographic strength of HMAC depends on the properties of the underlying hash function.
		Definition of HMAC The definition of HMAC requires a cryptographic hash function, which we denote by H, and a secret key K. We assume H to be a cryptographic hash function where data is hashed by iterating a basic compression function on blocks of data.
		In particular, it uses the function H with the pre-defined initial value IV (a fixed value specified by each iterative hash function to initialize its compression function).
	www.faqs.org /rfcs/rfc2104.html (2179 words)

	Hash Functions and Block Ciphers
		A hash function for hash table lookup should be fast, and it should cause as few collisions as possible.
		If you know the keys you will be hashing before you choose the hash function, it is possible to get zero collisions -- this is called perfect hashing.
		A cryptographic pseudorandom number generator is a random number generator where it is intractible to deduce the generator's internal state given any number of its results.
	burtleburtle.net /bob/hash (1349 words)

	The MD5 cryptographic hash function (in Technology > hashfunctions @ iusmentis.com)
		The MD5 function is a cryptographic algorithm that takes an input of arbitrary length and produces a message digest that is 128 bits long.
		The digest is sometimes also called the "hash" or "fingerprint" of the input.
		The contents of the four buffers (A, B, C and D) are now mixed with the words of the input, using the four auxiliary functions (F, G, H and I).
	www.iusmentis.com /technology/hashfunctions/md5 (443 words)

	Dr. Dobb's \| The RIPEMD-160 Cryptographic Hash Function \| July 22, 2001 (Site not responding. Last check: 2007-10-19)
		A cryptographic hash function takes an input string (message) of arbitrary size and reduces it to a short string of typically 16 or 20 bytes.
		At the end of the compression function, we compute the new state by adding one register from the left half and one from the right half on the same processor (see Figure 1).
		The 20-byte hash result is obtained by converting the final value of the 5-word internal state to a string of 20 bytes using a Little-endian convention.
	www.ddj.com /184410106?pgno=1 (2193 words)

	SHA-1 : SHA (Site not responding. Last check: 2007-10-19)
		SHA-1 (Secure Hash Algorithm) is a message digest algorithm (and cryptographic hash function) designed by the National Security Agency (NSA) and published by the National Institute of Standards and Technology (NIST).
		It produces a 160-bit digest from a message with a maximum size of 2^64 bits, and is based on principles similar to those used by Professor Ronald L. Rivest of MIT in the design of the MD4 and MD5 message digest algorithms.
		These new hash functions have not yet received as much scrutiny by the public cryptographic community as SHA-1 has, and so their cryptographic security isn't yet as assured.
	www.termsdefined.net /sh/sha.html (635 words)

	What is CheckSum (Hash value)?
		The first one is more general and means almost the same as "hash value", ie the value produced by any hash function or hash algorithm (for example, CRC32 One of checksum calculation algorithms family based on Cyclic Redundancy Codes.
		The second currently is used to name the hash values produced by simplest form of hash function, which simply adds up basic components of original input, typically the bytes.
		In cryptography the input data for hash function usually name as "message" and hash value for this message is named as "message digest".
	www.accuhash.com /what-is-checksum.html (846 words)

	[No title] (Site not responding. Last check: 2007-10-19)
		Additional information regarding the security of current one-way hash functions, as well as proposals for new one-way hash functions, are expected.
		The DSA signature algorithm requires a hash function whose output is 160 bits.
		The working group will consider at least two approaches to strengthen one-way hash functions for use in DSA: 1) Truncate a larger one-way hash function output so that it can be used as a secure replacement of a shorter one-way hash function output.
	www.ietf.org /ietf/05aug/hash.txt (421 words)

	Hash function - Wikipedia, the free encyclopedia
		A hash function (or hash algorithm) is a reproducible method of turning data (usually a message or a file) into a number suitable to be handled by a computer.
		Because of the variety of applications for hash functions (details below), they are often tailored to the application.
		It is based on the use of hashing to compare strings.
	en.wikipedia.org /wiki/Hash_function (1367 words)

	[No title]
		Universal Hash Function 5.1 External Interface 5.2 Hashing based on the NH primitive 5.2.1 Parameters 5.2.2 Mathematical Operations 5.2.3 Endian Re-Orientation 5.2.4 The NH hashing primitive 5.2.5 The NHx hashing primitive 5.2.6 The 2NHx hashing primitive 5.2.7 Universal Hash Function Based on NH Encoding 7.
		The pseudorandom function may be obtained (for example) from a block cipher or cryptographic hash function.
		Encoding The output of the hash function along with the nonce value must be packaged into an argument to the PRF function, using a reversible encoding.
	www.cs.ucdavis.edu /~rogaway/umac/1999/umac_spec.txt (2557 words)

	IMac (GNU cryptographic primitives and tools, version 2.0.0)
		When a MAC algorithm is based on a cryptographic hash function, it is then called to a HMAC (Hashed Message Authentication Code) --see RFC-2104.
		This hash function is non-cryptographic, in the sense that it does not need to have any cryptographic hardness property.
		The pseudorandom function may be obtained from a block cipher or a cryptographic hash function.
	www.gnu.org /software/gnu-crypto/manual/api/gnu/crypto/mac/IMac.html (564 words)

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