In cryptography, an HMAC is a specific type of message authentication code (MAC) involving a cryptographic hash function and a secret cryptographic key. As with any MAC, it may be used to simultaneously verify both the data integrity and authenticity of a message. An HMAC is a type of keyed hash function that can also be used in a key derivation scheme or a key stretching scheme.
The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value. MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function MD4, and was specified in 1992 as RFC 1321.
In cryptography, SHA-1 is a hash function which takes an input and produces a 160-bit (20-byte) hash value known as a message digest – typically rendered as 40 hexadecimal digits. It was designed by the United States National Security Agency, and is a U.S. Federal Information Processing Standard. The algorithm has been cryptographically broken but is still widely used.
A cryptographic hash function (CHF) is a hash algorithm that has special properties desirable for a cryptographic application:
In cryptography, Tiger is a cryptographic hash function designed by Ross Anderson and Eli Biham in 1995 for efficiency on 64-bit platforms. The size of a Tiger hash value is 192 bits. Truncated versions can be used for compatibility with protocols assuming a particular hash size. Unlike the SHA-2 family, no distinguishing initialization values are defined; they are simply prefixes of the full Tiger/192 hash value.
The MD4 Message-Digest Algorithm is a cryptographic hash function developed by Ronald Rivest in 1990. The digest length is 128 bits. The algorithm has influenced later designs, such as the MD5, SHA-1 and RIPEMD algorithms. The initialism "MD" stands for "Message Digest".
In cryptography, a collision attack on a cryptographic hash tries to find two inputs producing the same hash value, i.e. a hash collision. This is in contrast to a preimage attack where a specific target hash value is specified.
In cryptography, N-hash is a cryptographic hash function based on the FEAL round function, and is now considered insecure. It was proposed in 1990 in an article by Miyaguchi, Ohta, and Iwata; weaknesses were published the following year.
HAVAL is a cryptographic hash function. Unlike MD5, but like most modern cryptographic hash functions, HAVAL can produce hashes of different lengths – 128 bits, 160 bits, 192 bits, 224 bits, and 256 bits. HAVAL also allows users to specify the number of rounds to be used to generate the hash. HAVAL was broken in 2004.
Bart Preneel is a Belgian cryptographer and cryptanalyst. He is a professor at Katholieke Universiteit Leuven, in the COSIC group.
SHA-2 is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. They are built using the Merkle–Damgård construction, from a one-way compression function itself built using the Davies–Meyer structure from a specialized block cipher.
Hans Dobbertin was a German cryptographer who is best known for his work on cryptanalysis of the MD4, MD5, and original RIPEMD hash functions, and for his part in the design of the new version of the RIPEMD hash function. He was a member of the German Federal Office for Information Security and professor at the Ruhr University in Bochum.
FORK-256 is a hash algorithm designed in response to security issues discovered in the earlier SHA-1 and MD5 algorithms. After substantial cryptanalysis, the algorithm is considered broken.
In cryptography, the Merkle–Damgård construction or Merkle–Damgård hash function is a method of building collision-resistant cryptographic hash functions from collision-resistant one-way compression functions. This construction was used in the design of many popular hash algorithms such as MD5, SHA-1, and SHA-2.
An MDS matrix is a matrix representing a function with certain diffusion properties that have useful applications in cryptography. Technically, an matrix over a finite field is an MDS matrix if it is the transformation matrix of a linear transformation from to such that no two different -tuples of the form coincide in or more components. Equivalently, the set of all -tuples is an MDS code, i.e., a linear code that reaches the Singleton bound.
The following tables compare general and technical information for a number of cryptographic hash functions. See the individual functions' articles for further information. This article is not all-inclusive or necessarily up-to-date. An overview of hash function security/cryptanalysis can be found at hash function security summary.
This article summarizes publicly known attacks against cryptographic hash functions. Note that not all entries may be up to date. For a summary of other hash function parameters, see comparison of cryptographic hash functions.
In cryptography, security level is a measure of the strength that a cryptographic primitive — such as a cipher or hash function — achieves. Security level is usually expressed as a number of "bits of security", where n-bit security means that the attacker would have to perform 2n operations to break it, but other methods have been proposed that more closely model the costs for an attacker. This allows for convenient comparison between algorithms and is useful when combining multiple primitives in a hybrid cryptosystem, so there is no clear weakest link. For example, AES-128 is designed to offer a 128-bit security level, which is considered roughly equivalent to a RSA using 3072-bit key.
The Message Authenticator Algorithm (MAA) was one of the first cryptographic functions for computing a message authentication code (MAC).
Orr Dunkelman is an Israeli cryptographer and cryptanalyst, currently a professor at the University of Haifa Computer Science department. Dunkelman is a co-director of the Center for Cyber Law & Privacy at the University of Haifa and a co-founder of Privacy Israel, an Israeli NGO for promoting privacy in Israel.
