Questions tagged [hashing]
A hash function is any algorithm that maps data of arbitrary length to data of a fixed length. The values returned by a hash function are called hash values, hash codes, hash sums, checksums or simply hashes. From Wikipedia: http://en.wikipedia.org/wiki/Hash_function
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questions with no upvoted or accepted answers
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Using PostgreSQL MD5 hash to calculate a 64 bit hash value for advisory lock functions?
I have a particular problem addressing the PostgreSQL advisory locking functions using the bigint variants.
Basically I want to create a 64 bit bigint value from a text type obtained with the ...
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LSH for a wordlist
I am trying to write a spellchecker, I have a huge wordlist (at least 500K, because of the nature of the language). The performance would suffer a lot if I got the lavenshtein distance of all of the ...
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Hashing algorithm without the avalanche effect
I know that one of the most important features of hashing algorithms, is that minor changes in the input should reflect great change in the hash itself (the avalanche effect), but I'm currently ...
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Is the Rabin fingerprinting scheme with a random polynomial a universal hash function family?
Say I have a greater-than-expected number of collisions in my hash table that has 2^w buckets (half of them empty).
So I pick a fresh new random CRC polynomial that generates w-bit check values
(i.e., ...
- 1,362
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0
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Data structure for fast bi-directional SHA-1 to SHA-3 mapping
What data structure would be best choice for fast and performant bidirectional SHA-1 to SHA-3 mapping? Or in other words fixed-length string to fixed-length string mapping?
To be more precise:
...
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Consistent hash ring with subsets in different buckets
I have N buckets. I have M users. Each user can buy anywhere between 1 and N tickets to an upcoming lottery.
I would like to distribute the tickets more or less evenly between the buckets, with the ...
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1
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0
answers
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Generate a fixed length number hash from a number
Let say I've a fixed length number, e.g. 6 digit: 837493, I want to apply some process (with a salt), and generate a new number of another 6 digits,
e.g.
number = 837493
another = hash(number + ...
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Metrics for when to use a hash value?
I am working on a project that requires a series of flat files. I will be doing some data checking against simple date like:
ID;StatusCode
So a typical file might be like:
13993;R
38293;A
19349;I
...
- 249
1
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0
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Writing a container that treats nearly-identical images as the same
I want to create a mapping in Python that will use images as keys, but treat similar (but not identical) images as the same key. I have an approach for deciding which images are similar enough: I ...
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Does multiple Bloom filters make sense?
In order to decrease the number of false positives, I came up with a couple of possible solutions.
Create two different types of Bloom filters; eg. filter1 using 3 different hash algorithms, filter2 ...
user124114
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0
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Built-in Context-and-Input-to-Output-Hashing in Compilers
Why doesn't (open source) compilers contain builtin funtionality for (shared) caching and reuse-fetching (using SHA1-hash of compiler-version, build-flags, target-platform and inputs) of executable ...
- 151
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Where and if to declare Hash algorithm used
Not quite sure if this belongs here or on the crypto board...
Hi :)
We are using hash functions, not for hashing passwords but for digital signatures.
Architecture is having one gateway who has to ...
- 101
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248
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Designing a unique id reliably based on a String date?
I am creating an Android application that sets alarms based on the String date of a list of Objects (PendingIntents, with each taking in an id, that is an integer). In order to cancel the ...
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Searching/Hashing Wikipedia - at each position for keys 1..31 long, the fastest way?
A C coder here.
My wish is to find the best way to search words and phrases within the ever-growing English Wikipedia XML dump. As a first layer/step, hashing is the answer, yes?
The problem is that ...
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Partition stream of data between n servers, with m duplicates
I'm partitioning a stream of input data between n servers. The simple way of doing it is to use the hash of some property of each input data packet to assign a single server, using mod or similar, and ...
- 491
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portable hashable string representation of data object
I have a class of (flat) objects that are going to be passed around between three different parties, each possibly running a different software stack.
my_object:
item: "string_a"
money:
...
- 404
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1
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444
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Secure communication between a mobile app and a microcontroller
I have a MCU-based design that essentially controls other hardware and this MCU is controlled through an app. I was hoping someone could help me figure out how to secure this communication between the ...
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Find circular references of first order (bi-directional referencing)
I have million of objects, each with an array smaller than 10 elements, which are the names of other objects in the dataset.
Basically
{
a:[b,c,d,],
b:[c,d,e],
c:[a,e,f],
...
e:[a,b,c]
}
will ...
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