I am trying to perform broad-phase collision detection with a fixed-grid size approach. Thus, for each entity's position: (x,y,z) (each of type float), I need to find which cell does the entity lie in. I then intend to store all the cells in a hash-table and then iterate through to report (if any) collisions. So, here is what I am doing...
For a login system in php would this be a suitable outline of how it would work: users types in username and password, clicks login button. Checks if user exists in database, if it does, then retrieve the salt for that user hash the password and salt (would this be done on the client or server side? I think client side would be better...
I want to create a token generator that generates tokens that cannot be guessed by the user and that are still unique (to be used for password resets and confirmation codes). I often see this code; does it make sense? md5(uniqid(rand(), true)); According to a comment uniqid($prefix, $moreEntopy = true) yields first 8 hex chars = ...
phpass is a widely used hashing 'framework'. Is it good practice to salt the plain password before giving it to PasswordHash (v0.2), like so?: $dynamicSalt = $record['salt']; $staticSalt = 'i5ininsfj5lt4hbfduk54fjbhoxc80sdf'; $plainPassword = $_POST['password']; $password = $plainPassword . $dynamicSalt . $staticSalt; $passwo...
phpass is a widely used hashing 'framework'. While evaluating phpass' HashPassword I came across this odd method fragment. function HashPassword($password) { // <snip> trying to generate a hash… # Returning '*' on error is safe here, but would _not_ be safe # in a crypt(3)-like function used _both_ for gen...
I need to transmit some data over the wire and I don't want that data being plain text. The text I'm sending needs to be reversed so I can't md5/sha256/etc... What's a good way to encode a salted string? ...
In the .NET framework there are a couple of ways to calculate an MD5 hash it seems, however there is something I don't understand; What is the distinction between the following? What sets them apart from eachother? They seem to produce identical results: public static string GetMD5Hash(string str) { MD5CryptoServicePro...
I am working in python on appengine. I am trying to create what is equivalent to the "v" value in the youtube url's (http://www.youtube.com/watch?v=XhMN0wlITLk) for retrieving specific entities. The datastore auto generates a key but it is way too long (34 digits). I have experimented with hashlib to build my own, but again I get a lon...
I'm trying to create a sort of "virtual gallery". I'm using Coda Slider 2.0 & jQuery v1.4.2 It behaves perfectly in IE, FF & Safari, but Chrome seems to reload/hang for a second when setting location.hash. This causes the jQuery animation to freeze for a second :S Example: http://hardyernst.dk/gallery.html try clicking on the navigatio...
I am building a hash where the keys, associated with scalars, are not necessarily unique. The desired behavior to be that if the key is unique, the value is the scalar. If the key is not unique, I want the value to be an array reference of the scalars associated witht the key. Since the hash is built up iteratively, I don't know if the...
I have an object of type Hash that I want to loop over via hash.each do |key, value|. I would like to get the number of times I've been through the loop starting at 1. Is there a method similar to each that provides this (while still providing the hash key/value data), or do I need to create another counter variable to increment within...
I need to modify the hash, remove it after certain processing takes place so that if the user refreshes they do not cause the process to run again. This works fine in FF, but it seems that IE is reloading every time I try to change the hash. I think it is related to other things that are loading on the page, though I am not certain. I ...
Hello, I have a problem searching through amazon web servise using PHP in my CodeIgniter. I get InvalidParameter timestamp is not in ISO-8601 format response from the server. But I don't think that timestamp is the problem,because I have tryed to compare with given date format from http://associates-amazon.s3.amazonaws.com/signed-reques...
My Perl script have weird behaviour which I don't understand. I'm processing large structure stored as array of hashes which is growing while processing. The problem is that structure has about max 8mb when I store it on hdd, but while it is processing it takes about 130mb of ram. Why there is so big difference? The main flow of procce...
I have read through various papers on the 'Balls and Bins' problem and it seems that if a hash function is working right (ie. it is effectively a random distribution) then the following should/must be true if I hash n values into a hash table with n slots (or bins): Probability that a bin is empty, for large n is 1/e. Expected number o...
Im trying to create a datapager solution in asp.net like the one on the http://channel9.msdn.com/Posts/ website. The solution should work like this: Listview inside a updatepanel (partial rendered / updated) based on hashed pageindex from querystring Support for navigation history points, so if someone goes to a detail page of one the...
I'm trying to think up a good hash function for strings. And I was thinking it might be a good idea to sum up the unicode values for the first five characters in the string (assuming it has five, otherwise stop where it ends). Would that be a good idea, or is it a bad one? I am doing this in Java, but I wouldn't imagine that would mak...
I was helping with an answer in this question and it sparked a question of my own. Pie is an object that has a pieces array made of of PiePiece objects. Each PiePiece has a flavor attribute How do I create a hash that looks like this: # flavor => number of pieces { :cherry => 3 :apple => 1 :strawberry => 2 } This works, but ...
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. ...
I don't mean for this to be a debate, but I'm trying to understand the technical rationale behind why so many apps use SHA1, when SHA512 is more secure. Perhaps it's simply for backwards compatibility. Besides the obvious larger size (128 chars vs 40), or slight speed differences, is there any other reason why folks use the former? Als...