Jul 13, 2014 · The definition of a cryptographic hash function includes resistance to preimages: given h(x), it should be infeasible to recover x. A hash function being "reversible" is the exact opposite of that property. Therefore, you can have no more a "reversible hash function" than you can have a fish allergic to water.

There are only 2^256 outputs of the hash function. Thus, for each output of the hash function, there are roughly 2^256 512 bit strings which hash to that value. I say roughly because we don't know if the hash function actually is a random function, it could have slight biases. Thus, given a digest, there are many strings which hash to the same ...

Jan 19, 2022 · Quick: it is quick to compute the hash value for any given message; One-way function: it is infeasible to generate a message from its hash value except by trying all possible messages; Avalanche effect: a small change to a message should change the hash value so extensively that the new hash value appears uncorrelated with the old hash value;

Apr 6, 2017 · A cryptographic hash function is a special class of hash function that has certain properties which make it suitable for use in cryptography. Useful reading - it goes into more detail of the reversibility of hash functions intended to be hard to reverse.

Sep 1, 2017 · The values returned by a hash function are called hash values, hash codes, digests, or simply hashes. One use is a data structure called a hash function, widely used in computer software for rapid data lookup. For example, suppose that you want to count the number of occurrences of the alphabets in a string. Always remember that the hash digest ...

Jan 25, 2011 · A MAC is used for message authentication, and is a symmetrically keyed primitive. A hash function can be used for many purposes, and has no special key input. MAC is an acronym of "message authentication code". Don't be confused by the fact that some MAC algorithms (e.g., SHA1-HMAC) work by using a hash function as a subroutine.

Essentially the only attack that [edit: might] break it more completely is a second preimage attack. Either, however, basically means that what you have isn't a cryptographic hash function at all any more -- the whole point of a cryptographic hash is that it's a one-way function, but either sort of preimage attack means it's now a two-way function.

Mar 4, 2016 · A hash function of infinitely many bits would circumvent the normal-distribution requirement. However, a requirement of a hash function is for it to produce a fixed length output, so such a function would not technically be a hash function. Finally, there are a few different Wikipedia pages discussing hash functions and one of them says this: A ...

It [AES] results in a hash function with a 128-bit output. The intermediate output of the cipher in cipher-as-a-hash function has variable length and depends on the length of the input. The final output of cipher-as-a-hash function has N bits, where N is chosen by the designer of the cipher-as-a-hash function.

Mar 14, 2022 · There is a method to make a hash function based on the block cipher. I am curious whether there is a difference between AES encryption and hash function with the strong assumptions as below: A. The key of the AES is never exposed. (Without knowing the key, I believe there is no possibility of decryption and hence one-way function as a hash) B.