hash-collision Questions

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I was going through Java's implementation of the put method for a hashtable and came across this : // Makes sure the key is not already in the hashtable. Entry tab[] = table; int hash = key.has...
Darling asked 18/10, 2012 at 19:23

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I was reviewing for my data structures final exam, and I came across a question in past year's final. Having worked on it for the past three hours, I still couldn't figure out a way to solve it, ex...
Snapdragon asked 17/5, 2012 at 2:59

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I have to find SHA256 hashes of 2^25 random strings. And then look for collision (using birthday paradox for the last, say, 50 bits of the hash only). I am storing the string:hash pair in a dict v...
Antiseptic asked 10/4, 2012 at 13:3

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What's the probability for the clash for the md5 algorithm? I believe it is extremely low.
Gerdi asked 13/1, 2012 at 15:12

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I'm trying to implement an collision attack on hashes (I'm visiting the course 'cryptography'). Therefore I have two arrays of hashes (= byte-sequences byte[]) and want to find hashes which are pre...
Rave asked 2/1, 2012 at 12:58

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As reported by Slashdot, MS issued an update to ASP.NET to fix the hash collision attack today. (Listed as "Collisions in HashTable May Cause DoS Vulnerability - CVE-2011-3414" on the linked ...
Fiore asked 29/12, 2011 at 20:25

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I know hashing infinite number of string into 32b int must generate collision, but I expect from hashing function some nice distribution. Isn't it weird that these 2 strings have the same hash? s...
Kite asked 1/11, 2011 at 15:19

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I need to compare large chunks of data for equality, and I need to compare many pairs per second, fast. Each object is guaranteed to be the same length, it is possible and likely that there may onl...
Debonair asked 4/10, 2011 at 10:31

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I wonder if it is 'safe' to hash a bunch of MD5 hash values together to create a new hash or whether this will in any way increase the probability of collisions. The background: I have a couple of...
Walley asked 18/9, 2011 at 12:39

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Interestingly I haven't found enough information regarding any test or experiment of collision chances of single 512bit hash like whirlpool versus concatenation of 4 128bit hashes like md5, sha1 et...
Armil asked 13/9, 2011 at 20:10

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What is the difference between a multi-collision in a hash function and a first or second preimage. First preimage attacks: given a hash h, find a message m such that hash(m) = h. Second preimage...

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I wanted to understand how the SHA0 hash function was broken. I understand that utilising the birthday problem/pigeon-hold principle, hash collision(s) were found. http://www.mail-archive.com/crypt...
Attendance asked 7/7, 2011 at 15:42

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I had the following code to generate a hash of an object: public int GetHashCode(MyType obj) { return (obj.Prop1.GetHashCode() + obj.Prop2.GetHashCode() + obj.Prop3.GetHashCode()).GetHashCode(); ...
Roseleeroselia asked 8/6, 2011 at 21:57

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Can any one give an example of 2 strings, consisting of alphabetical characters only, that will produce the same hash value with ELFHash? I need these to test my codes. But it doesn't seem like ea...
Mcnully asked 7/5, 2011 at 9:43

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I need a 4-character hash. At the moment I am taking the first 4 characters of a md5() hash. I am hashing a string which is 80 characters long or less. Will this lead to collision? or, what is the ...
Grating asked 13/1, 2011 at 15:42

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According to various sources, such as Wikipedia and various .edu websites found by Google, the most common ways for a hash table to resolve collisions are linear or quadratic probing and chaining. ...

3

Up to what string length is it possible to use MD5 as a hash without having to worry about the possibility of a collision? This would presumably be calculated by generating an MD5 hash for every p...
Skipper asked 4/1, 2010 at 14:27

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I'm looking for a hashtable implementation in C that stores its objects in (twodimensional) arrays rather than linked lists. i.e. if a collision happens, the object that is causing the collision wi...
Dutra asked 28/4, 2010 at 15:58

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I have a problem with a custom object that needs to be keyed for a table. I need to generate a unique numeric key. I'm having collision problems and I'm wondering if I can leverage a dictionary to ...
Pawn asked 10/2, 2010 at 20:48

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I was reading the Java api docs on Hashtable class and came across several questions. In the doc, it says "Note that the hash table is open: in the case of a "hash collision", a single bucket store...
Ratliff asked 17/8, 2009 at 15:43

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This is basically a math problem, but very programing related: if I have 1 billion strings containing URLs, and I take the first 64 bits of the MD5 hash of each of them, what kind of collision freq...
Concertina asked 8/7, 2009 at 7:15

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I've got a table of 5,651,744 rows, with a primary key made of 6 columns (int x 3, smallint, varchar(39), varchar(2)). I am looking to improve the performance with this table and another table whic...
Clea asked 22/6, 2009 at 19:42

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If someone is purposely trying to modify two files to have the same hash, what are ways to stop them? Can md5 and sha1 prevent the majority case? I was thinking of writing my own and I figure even...
Scarify asked 8/3, 2009 at 2:44

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