Thinking about this question on testing string rotation, I wondered: Is there was such thing as a circular/cyclic hash function? E.g. h(abcdef) = h(bcdefa) = h(cdefab) etc Uses for this include scalable algorithms which can check n strings against each other to see where some are rotations of others. I suppose the essence of the hash...
I have often heard people talking about hashing and hash maps and hash tables. I wanted to know what they are and where you can best use them for. ...
I have a struct called Point. Point is pretty simple: struct Point { Row row; Column column; // some other code for addition and subtraction of points is there too } Row and Column are basically glorified ints, but I got sick of accidentally transposing the input arguments to functions and gave them each a wrapper class. ...
So there is this nice picture in the hash maps article on Wikipedia: Everything clear so far, except for the hash function in the middle. How can a function generate the right index from any string? Are the indexes integers in reality too? If yes, how can the function output 1 for John Smith, 2 for Lisa Smith, etc.? ...
Is there a way to specify the hash algorithm (MD5, SHA1, etc.) to use for storing the passwords when you update an Open LDAP directory using Java APIs with code like this: private void resetPassword(String principal, String newPassword) throws NamingException { InitialDirContext ctxAdmin = null; Hashtable<String, String> ctxData = n...
Here is my plan, and goals: Overall Goals: Security with a certain amount of simplicity & database-to-database transferrability, 'cause I'm no expert and could mess it up and I don't want to have to ask a lot of users to reset their passwords. Easy to wipe the passwords for publishing a "wiped" databased of test data. (e.g. I'd like t...
Hi Guys, I have read through the source code for mplsh, but I still unsure on how to use the indexes generated by lshkit to speed up the process in comparing feature vector in Euclidean Distance. Do you guys have any experience regarding this? ...
Our computer system at work requires users to change their password every few weeks, and you cannot have the same password as you had previously. It remembers something like 20 of your last passwords. I discovered most people simply increment a digit at the end of their password, so "thisismypassword1" becomes "thisismypassword2" then 3,...
Hello. I am looking to take a hash range (md5 or sha1) and split it into n equal ranges. For example, if m (num nodes) = 5, the entire hash range would be split by 5 so that there would be a uniform distribution of key ranges. I would like n=1 (node 1) to be from the beginning of the hash range to 1/5, 2 from 1/5 to 2/5, etc all the wa...
So im just playing around with PHP and the MD5 functionality, sorry if this sounds really silly, but I cant seem to understand, how is it possible to represent an unlimited number of characters of input into a 32 bit character output? Is my logic sound here? Or is there a limit to the input that a MD5 function can take? Thanks... ...
I don't fully understand hashing algorithms. Anybody care to explain it to me in a very simply understandable way. Thanks EDIT: Using it with Usernames from a text file. ...
I have a simple class: public class TileName { int Zoom, X, Y; public override bool Equals (object obj) { var o = obj as TileName; return (o != null) && (o.Zoom == Zoom) && (o.X == X) && (o.Y == Y); } public override int GetHashCode () { return (Zoom + X + Y).GetHashCode(); } } I w...
Hi ! In Crypto communities it is common to measure algorithm performance in cycles/byte. My question is, which parameters in the CPU architecture are affecting this number? Except the clockspeed ofcourse :) ...
Hi, A bloom filter uses a hash function (or many) to generate a value between 0 and m given an input string X. My question is how to you use a hash function to generate a value in this way, for example an MD5 hash is typically represented by a 32 length hex string, how would I use an MD5 hashing algorithm to generate a value between 0 a...
I've heard that MD5 is "broken" (in the context of password encryption). But I don't understand why! I've read the theory, but can't see it happening in practice... I have an MD5 hash 99e9446e78aac2056d3903e1adb8fbcd And a simple bit of code to produce it $salt="#bh35^&Res%"; $pass="***"; //number of characters is not equal to number ...
I read a while back that Quantum Computers can break most types of hashing and encryption in use today in a very short amount of time(I believe it was mere minutes). How is it possible? I've tried reading articles about it but I get lost at the a quantum bit can be 1, 0, or something else. Can someone explain how this relates to cracking...
I have written a program to store a bunch of strings in a JFC hash table. There are defiantly collisions going on, but I don't really know how it is handling them. My ultimate goal is to print the number of occurrences of each string in the table, and traversing the bucket or list would work nicely. Or maybe counting the collisions? O...
Well, from the discussion of hashing methods weaknesses, I've got that the only ol' good brute-force is efficient to break. So, the question is: Is there a hashing algorithm which is more rigid against brute-force than others? In case of hashing passwords. ...
Conclusion: SHA-1 is as safe as anything against preimage attacks, however it is easy to compute, which means it is easier to mount a bruteforce or dictionary attack. (The same is true for successors like SHA-256.) Depending on the circumstances, a hash function which was designed to be computationally expensive (such as bcrypt) might be...
I use MD5 hash for identifying files with unknown origin. No attacker here, so I don't care that MD5 has been broken and one can intendedly generate collisions. My problem is I need to provide logging so that different problems are diagnosed easier. If I log every hash as a hex string that's too long, inconvenient and looks ugly, so I'd...