All Questions
Tagged with compression hash
15 questions
0
votes
2
answers
116
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Compression algorithm with multiple valid same-sized outputs
Is there a lossless compression algorithm that has hashing-like properties where there are multiple solutions to it?
As in for example, when a 1000-bit data-sequence is compressed into a 500-bit data ...
- 27
0
votes
1
answer
47
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Hashing functions that allow to walk back to parts of cleartext?
Say $m$ is some clear text, and $h_n(m)$ is its $n$ bits hash.
The question: How can we design $h_n$ so that we can extract maximum information about $m$ from $h_n(m)$?
The reason I ask this is ...
- 573
9
votes
3
answers
4k
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Can one use a reversible hash algorithm as a compression function?
As we know any input to SHA-256 will be returned as 64 hex length output. Is it possible to create a hash that can do the same thing as SHA-256 but can be reversed, so if we have the output of 64 ...
- 107
5
votes
2
answers
2k
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What is the difference between data compression and compression in cryptographic algorithms?
What is the differences between data compression as used in e.g. the ZIP protocol and compression as performed in cryptographic hashes? Are there common properties as well, apart from creating a ...
- 94.5k
2
votes
1
answer
104
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Checksum for bailing early on first corrupt byte in stream?
Suppose you want to transmit bytes of a file from computer a to b, but you want to bail early if any of the bytes are wrong.
It’s easy to prescribe a hash/checksum implementation for the entire file. ...
- 235
8
votes
6
answers
16k
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Can a large file be hashed down to 32 bytes, and then reconstructed from the hash? [duplicate]
We can hash a file or data using multihash or SHA-256, but can we retrieve the original data or file from the hash?
Are there any methods to retrieve the original file or data from a hash of it ...
- 368
4
votes
2
answers
2k
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AES-128 as compression function in Merkle-Damgard construction
Using a compression function $f : A × A → A$. A basic version
given by:
$W_0 = IV$
$W_1 = f(W_0, m_1)$
$W_2 = f(W_1, m_2)$
...
$W_n = f(W_{n-1}, m_n)$
$W_n$ is the output of the hash function, $...
- 71
1
vote
1
answer
610
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Can a compressed checksum be considered unique
I'm kind of guessing that the answer may be no. Since the compression is trying to reduce the output size using various optimization methods, this may cancel the properties of a hash algorithm.
But ...
- 113
6
votes
6
answers
13k
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Why can't we use a hash with no collision to compress data reliably?
According to Wikipedia, a hash maps digital data of arbitrary size to digital data of fixed size.
For all practical measures, a hash is a unique signature of a big chunk of data. But there is such a ...
- 176
0
votes
1
answer
771
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Huffman encoding of hashes
I have a huge list of MD5 hashes, which takes up quite some space. I wonder whether I would achieve (some) compression by encoding the characters (which are A-F 0-9), with Huffman coding. I made a ...
- 145
1
vote
1
answer
1k
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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-Damgård construction with the underlying compression function based on the block cipher SHACAL-2 configured in Davies Meyer mode. SHACAL-2 ...
- 1,105
1
vote
1
answer
297
views
Keccak and compression functions
Keccak follows a sponge construction. Can we say that Keccak employs a compression function? Generally speaking, for sponge constructions, can we say that there is an underlying compression function?
- 2,897
4
votes
1
answer
247
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Compression function to guarantee randomness of one time pads?
First of all, I would like to note that I am not building my own crypto. I am simply curious and would like to learn.
What I am wondering is this: if we are worried about randomness of something ...
2
votes
2
answers
2k
views
Does it make sense to have a compression function that uses 64-bit of the message to create an output of 64-bit?
I have a very simple compression function, which looks like this in C++:
...
- 31
2
votes
2
answers
356
views
Seeking special-use fingerprinting/hashing algorithm
For a project I wonder if there exists some kind of fixed-size checksumming/fingerprinting function in which based on this fingerprint given data block 1, it is easy to generate more data blocks that ...
- 153