A cryptographic hash algorithm is a function which takes a variable size input and produces a fixed size output. The algorithm makes it difficult to predict the output for a given input, find two inputs with the same output, or reconstruct the input from the output.

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Using Whirlpool hashing function to encrypt data

I've read that the Whirlpool hash function can produce footprints that could be used as a pseudorandom generator. Is it "OK" to use it to encrypt some data using something like the following? ...
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Does collision resistance stay when extending a hash function to a set domain?

Given a Cryptographic hash function $h$ for element $x$, let's extend it to sets via $H(S)=\prod_{x\in{S}}{h(x)}$. I am asking if the new hash $H$ (in domain of set) is still collision resistant? To ...
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Why is $h(H, m) = E(m, H) \oplus m$ insecure?

I am taking a cryptography class on Coursera. I learned that the compression function $h(H, m) = E_m(H) \oplus m$ is insecure (even though other variants like Davies­-Meyer or Miyaguchi-Preneel are ...
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How hard is a known prefix hash preimage attack?

Suppose the attacker knows $X, Z$ such that $H(X || Y) = Z$ If bit-length(Y) < 60 then a brute force attack is possible. What if ...
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Computational feasible to reverse MD5SUM?

This might be out of ignorance, I apologize, but how complex of a problem might it be to generate a file of size $N$ whose MD5SUM is $X$? For example, ...
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Looking for cryptographic secure hash algorithm(s) that produces identical root hash for differently sliced hash list

I have a scenario similar to the one described in Wikipedia: hash list, but with a twist. I'm looking for a cryptographically secure hash function that would create the same root hash for the same ...
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Hash functions vs. keyed hash functions in the context of private key generation

I'm designing a key distribution mechanism and have thought of using a securely generated/acquired private key as a seed for a sequence of private keys to be distributed to a number of users using a ...
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Converting a pre-image resistant hash to second pre-image resistant

I am looking for some standard conversion from any hash function $f$, which has pre-image resistance, to another hash function with second preimage resistance. Is there such a standard conversion?
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SHACAL-2 vs. AES as underlying block cipher for Secure Hash (aka SHA-256)

The hashing scheme SHA-256 (for instance) is based on Merkle-Damgard construction with the underlying compression function based on the block cipher SHACAL-2 configured in Davies Meyer mode. SHACAL-2 ...
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Security of chameleon hash functions

With the knowledge of the trapdoor, we are able to compute the same digest for differents messages. I've read that given two messages $m$, $m'$ and two numbers $r$, $r'$ such that ...
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Are partial hashes used in cryptographic protocols?

In my question (and answer) about a partial hash code used within a signature application I found out that partial hash codes are sometimes used within protocols with a relatively restricted security ...
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SHA1 collision event probability after n iterations

There are String1 and String2 - some variables-strings. The probability of collision for different ...
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Why don't we use H(m||k) as a MAC? [duplicate]

HMAC seems a bit complicated. Why can't we use $H(m||k)$ as a MAC? Unlike $H(k||m)$, length extension attacks won't work. Is there some other obvious attack?
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Does it make sense to stretch non-keys?

I was thinking about stretching salt. Key-stretching is good against brute force guessing and assumes your system isn't compromised. Salting a one-way makes it so you have to compute * n for each ...
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HMAC vs Encrypted Hash

What is best to use (for message integrity) between… AES(Data) + HMAC(Data) AES(Data + HMAC(Data)) AES(Data + Hash(Data)) …and why?
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Store hashed email and compare hash values

I have a number of different systems sending me email addresses, but I don't actually need the underlying email, just a hash of the email address. I know I can compare hash values to find matches ...
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Crack cryptographic hash functions using Toffoli gates?

Might it be possible that reversible combinatorial circuits (or some emulating software) are going to be used to get the input of the white box? I mean if I have constructed a proper reversible ...
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Elliptical curve cryptography Determine if a public key point y is negative or positive, odd or even?

Take a Elliptical curve cryptography public key (x, y) and its additive inverse (x, -y). How do you identify which is the positive point and which is the negative point? Example Private key 1 -> (x, ...
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Can you find the search space? [duplicate]

Let A is a random number and has 512 bits.we make B from A and B has 1024 bits.Process of B is following: C=f(A) that f is hash and C has 160 bits.Then C pass in a parallel manner 7 different hash ...
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How Does Progressive Hashing Work?

Example: http://jsfiddle.net/KGtUE/ https://code.google.com/p/crypto-js/#Progressive_Hashing sha256.update("abc"); sha256.update("def"); sha256.update("ghi"); ...
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Reversing a Psuedo Crytographic Hash [closed]

I'm trying to get a better understanding of cryptographic hashing. Take the example transformation function below, is it possible to reverse this formula to solve/isolate for message[i]? ...