Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [avalanche]

The avalanche effect is evident if, when an input is changed slightly (for example, flipping a single bit) the output changes significantly (e.g., half the output bits flip).

The avalanche effect is evident if, when an input is changed slightly (for example, flipping a single bit) the output changes significantly (e.g., half the output bits flip).

In the case of high-quality block ciphers, such a small change in either the key or the plaintext should cause a drastic change in the ciphertext. The actual term was first used by Horst Feistel, although the concept dates back to at least Shannon's diffusion.

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Understanding how SHA-512 achieves its design goals

The Wikipedia entry on SHA-2 contains a usable pseudocode recipe. In the hope of some deeper understanding, I implemented SHA-256 and SHA-512 from it. This was helpful, but I still don't think I have joined together my understanding of how the…
Neil Slater
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How many bits in the resultant hash will change, if the x bits are changed in its the original input?

I came across a question stating: We have a message consisting of 10,000 characters. After computing its message digest using SHA-1, we decide to change the last 19 characters in the original message. How many bits in the digest will change if it…
Vasu Deo.S
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Calculation of the avalanche effect coefficient

Given a strict avalanche criterion matrix/dependence matrix for a hash function,how do I calculate the avalanche coefficient for it. I want to calculate a single parameter(value) which represents the amount of avalanche effect for the given hash…
Kishan Kishore
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Strict Avalanche Criterion and Avalanche criterion?

What is the difference between Strict Avalanche Criterion(SAC) and Avalanche criterion?
Sangeetha
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Determine whether bit sequence is hash?

I would like to know whether it is possible to determine whether a value of for example 256 bit length is a SHA-256 hash or a random, equally distributed value. Is there any research related to common hash functions? Can this property be derived…
Julian Bruckner
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Simple reversible algorithms that satisfies SAC

What are some simple algorithms that … operate on a block of fixed size (or can be easily made to do so), i.e. the input block has a fixed size, e.g. 256 bit, and the output is a block of the same size are reversible (can't be a hash…
mistercake
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How to assess the strength of the avalanche effect for AES?

Within the scope of a study project I'm looking for an approach to assess the quality of AES encryption in practice. To do so, I modified the OpenSSL source code to be able to log metrics while encrypting thousands of blocks to obtain a…
Oliver Jl
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Any stream cipher with avalanche effect?

As far as I know, all stream ciphers work by generating a stream of pseudo random bytes, and XOR it with the plain text to get the cipher text. It has the property that one bit change in the cipher text results only the corresponding bit change in…
Wu Yongzheng
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Avalanche effect sample size

With a fixed key size – key has 128 bits, while block size is 8 byte – how do I calculate how many different keys and texts I have to test for an cryptanalytic statistics study? Differently worded: I am planning to encrypt multiple samples and see…
Jesús Martín Berlanga
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Need 32-bit mixing function that has perfect avalanche between octets

for my hobby tinkering project, I need a mixing function that takes 32-bit input and has 32-bit output (and will, most likely, run in a 32-bit C environment) and the following property (independent of endianness, i.e. it’s enough to only look at…
mirabilos
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All-or-nothing transform that doesn't increase message size?

All of the AON transforms I've read about involve generating a key, which increases the message by a few bytes. Is there an AON transform that preserves the message size while still having avalanche properties?
Daffy
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How can I calculate the avalanche effect in symmetric algorithms?

I am working with symmetric algorithms in Java with javax.crypo and Bouncy Castle libraries and I need to calculate the avalanche effect of different symmetric algorithms such as DES, 3DES, Blowfish and AES. I have read about the avalanche effect…
CGG
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What does the strict avalanche criterion mean?

I can build black box ciphers with the following properties: Satisfies SAC, but is trivially weak (a keystream from an LFSR seeded with the key). Does not satisfy SAC, but built from secure primitives (Base64 encode the output of AES). From 1 you…
hugh.m
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Hash functions and the Avalanche effect

Informally, the Avalanche effect says that two similar, but not identical, inputs should produce radically different outputs when fed through a hash function. I've seen, at least, two formal definitions of the effect. The first is that if we flip…
Fredrik Savje
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What are some hashes that do not exhibit the avalanche effect?

I do not know much about cryptography. But, I'm in a situation where I need a hashing method that does not exhibit the avalanche effect. I tried Googling but couldn't find anything.
user24533
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