1
vote
2answers
2k views

Finding duplicate files? [duplicate]

I am going to be developing a program that detects duplicate files and I was wondering what the best/fastest method would be to do this? I am more interested in what the best hash algorithm would be ...
1
vote
1answer
709 views

How to test if a hashing algorithm is good? [duplicate]

Possible Duplicate: Which hashing algorithm is best for uniqueness and speed? I have created a hash algorithm and would like to test if it is usable. What do I need to test and how?
4
votes
0answers
139 views

How to get a one-way hash function that is collision safe for about 1 million unique inputs? [duplicate]

Forgive me if this is a noob question - My CS education is a somewhat incomplete Basically, I need a way to hash an input, so that someone seeing the output doesn't see the original input value. ...
-1
votes
1answer
116 views

What are some hashmaps we can easily implement? [duplicate]

At many places, I read that we can use HashMap here for O(1) search. Actually, I want to ask how I can implement easy hashmaps which can satisfy this property. Can anyone tell few hashmaps including ...
0
votes
0answers
22 views

Storing usernames and email addresses with hashes [duplicate]

I need to store usernames and email addresses with hashes, and not make them reversible back to their original values. This is for validating that I have their username or email address. The table ...
18
votes
6answers
2k views

What makes a hashing algorithm “secure”?

After reading this interesting question, I felt like I had a good idea of which insecure hashing algorithm I'd use if I needed one, but no idea why I might use a secure algorithm instead. So what is ...
2
votes
11answers
3k views

I don't understand why algorithms are so special [closed]

I'm a student of computer science trying to soak up as much information on the topic as I can during my free time. I keep returning to algorithms time and again in various formats (online course, ...
6
votes
3answers
521 views

Is using hashes for primary keys a good idea?

The Austrian electronic ID card relies on the so-called sector identifiers. For example a hospital gets to identify a person by getting a sectorId for that person, which is computed roughly as ...
1
vote
2answers
1k views

Data Aggregation of CSV files java

I have k csv files (5 csv files for example), each file has m fields which produce a key and n values. I need to produce a single csv file with aggregated data. I'm looking for the most efficient ...
5
votes
1answer
829 views

Hash Algorithm Randomness Visualization

I'm curious if anyone here has any idea how the images were generated as shown in this response: Which hashing algorithm is best for uniqueness and speed? Ian posted a very well-received response but ...
0
votes
2answers
338 views

Randomized Hash function with no collisions

Related to the question Which hashing algorithm is best for uniqueness and speed? Is there a way to create a hash function, or find one, whose hash length depends completely on the input length, has ...
0
votes
3answers
148 views

Unique ID algorithm

I've got a route that contains objects. Each one has value 0 or 1. I need unique route ID which will identify any objects order. Currently I'm doing it using binary number that is converted to decimal ...
-1
votes
1answer
280 views

How to create a some kind of value for sentences? [closed]

I want to identify most matching sentence using some pattern. That means by using java algorithm I want to create identical value for each sentences.Each sentence when entering to that algorithm can ...
0
votes
2answers
407 views

How deterministic are SessionIDs from SHA'd GUIDs?

Assume I'm using the following code to generate pseudo-random sessionID's: sessionID = SHA-512(GENERATE-GUID()) The GUIDs are pretty deterministic, i.e. I see lots of GUIDs with a lot of the same ...
3
votes
1answer
92 views

Should changes to FNV-1A's input exhibit the avalanche effect?

This is kind of related to Which hashing algorithm is best for uniqueness and speed?. In that question, the excellently written top answer notes, Randomnessification The other subjective ...