# 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).

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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....
1 vote
269 views

### Hamming Distance and Avalanche effect in Cryptography?

I am new to Cryptography and I know there are better ways to test a cipher's effectiveness out there but in this case I am trying to test a cryptographic algorithm's(AES,xchacha20,twofish) hamming ...
438 views

### 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 ...
1 vote
201 views

### AES - SBOX avalanche effect question

I am making a program that verifies the avalanche effect for the SBOX of the AES block cipher for a certain number of iterations. This program changed one bit randomly in one of the elements of the ...
1 vote
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### How often group of queried nodes are changed in snowball/avalanche consensus algorithm?

I think I understand snowball consensus algorithm with exception of 1 think. Node polls 5-10 random nodes N times and choose color. Is it querying always same list of nodes? Or it is changed after ...
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### Is there any relationship between avalanche and permutation in block ciphers?

Avalanche is one of the characteristics of S-Box or SP network(S and P boxes are used together).Is it possible for the permutation module, when tested alone, to show avalanche effect.? reference SP ...
56 views

### 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 ...
1 vote
1k views

### How to find the 6 main properties of cryptographic hash functions when implementing a hash function?

According to this there are at least 6 "properties" all cryptographically secure hash functions strive to attain: Deterministic: the same message always results in the same hash; Quick: it ...
443 views

### Does SHA-1 meet the strict avalanche criterion?

Does SHA-1 meet the strict avalanche criterion? I've been looking for a paper to cite on this, but haven't found one. It's something that seems to be easy to check (in "On the Design of S-Boxes", ...
984 views

### Strict Avalanche Criterion (SAC)

I would like to know the step by step method to construct the SAC dependence matrix for AES S-Box. Can someone help me?
228 views

### Construct block cipher from a smaller one with mixing function

I read about the AEZ encryption scheme as presented at the CAESAR competition. To me it seems like a construction of an arbitrary length block cipher from a smaller one. The key component is the ...
787 views

### Optimal bit-change-probability of the avalanche effect for hashes

Avalanche effect: The strict avalanche criterion (SAC) is a formalization of the avalanche effect. It is satisfied if, whenever a single input bit is complemented, each of the output bits changes ...
1 vote
958 views

### how to compute Bit Independent Criteria on a 4-bit S-box?

The idea of Bit Independence Criterion (BIC ) was introduced by Webster and Tavares . For a given set of avalanche vectors generated by complementing a single plaintext bit, all avalanche variables ...
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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 ...
6k views

### 8-bit CFB in DES and AES - error propagation

I have two questions for an assignment that I need to answer in relation to Error Propagation in 8-bit CFB mode for AES and DES encryption. The questions are as follows: If there is an error in ...
356 views

### What affect does the permutation layer have on the avalanche effect?

If the permutation is not well thought out, how will this effect the cipher's avalanche effect. For example, if the permutation in PRESENT was in some way different (just made up without any thought) ...
1 vote
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### How to evaluate the avalanche effect? [duplicate]

How can avalanche effect be calculated? I would in particular want to know what platform or IDE can be used to calculate the same?
295 views

### Are there any deterministic multi-block encryption constructions that have an avalanche effect going both ways?

For common multi-block encryption schemes (CBC, CTR, CFB, stream ciphers, etc), if they are forced to be deterministic, a change in the plaintext will change only the current block and maybe future ...
1k views

### 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 ...
354 views

### Plaintext formation for checking avalanche effect

I have developed an encryption algorithm. Now i want to check avalanche effect by making one bit change in plaintext and observing how many bits are changing in ciphertext. But my doubt is "what is ...
4k views

### Strict Avalanche Criterion and Avalanche criterion?

What is the difference between Strict Avalanche Criterion(SAC) and Avalanche criterion?
250 views

### Can the statistical width of the avalanche effect be calculated?

This question follows on from my answer to calculation-of-the-avalanche-effect-coefficient earlier. I have reproduced the graph for this question. Consider the red line which represents the number ...
1k views

### 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.
785 views

### 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 ...
2k views

### DES 1-bit changes to inputs: why when I change two inputs by only one bit I get predictable results?

I expected a 1-bit change to two inputs (same key) would provide differences to 50 per cent of the output bits (on average). But this is not the case when I tested it. However, for two 'identical' ...
3k views

### 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 ...
4k views

### 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 ...
661 views

### 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 ...
5k views

### 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 ...
929 views

### 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 ...
1 vote
119 views

### Determining the degree of freedom for a chi-squared test on a strict avalanche criterion matrix

I have read that the degree of freedom is calculated by subtracting 1 from the number of states a random variable can be in. I am performing a goodness of fit test on a 64*32 strict avalanche ...
1 vote
496 views

### Is there an avalanche effect using block cipher modes of operation?

I am studying cryptography and various block cipher modes of operation. Suppose I changed one bit in the last block of the message. Wouldn't that imply no change in all encrypted blocks except for ...
530 views

### 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: ...
1 vote
1k views

### How to calculate the avalanche effect in aes-256?

I am a beginner in cryptography. I'm testing AES-128 bit key, AES-256 bit key, and Camellia-256 bit key. I'm using AES-256, 9 character salt, CBC mode, PKCS #5 padding, and the ciphertext using ...