hashing

What kind of hashing algorithm used to generate 12 character length alphanumeric?

What kind of hashing algorithm used to generate 12 character length alphanumeric? for example stackoverflow use 2 keys to store cookies t=IhweorwSw6K7 s=............ (#intentionally replace with . because its a session cookies) How does that hashing algorithm looks like? ...

How do you embed a hash into a file recursively?

Simplest case: You want to make a text file which says "The MD5 hash of this file is FOOBARHASH". How do you embed the hash, knowing that the embedded hash value and the hash of the file are inter-related? eg, Cisco embeds hash values into their IOS images, which can be verified like this: cisco# verify s72033-advipservicesk9_wan-mz...

Perfect hash in Scala.

I have some class C: class C (...) { ... } I want to use it to index an efficient map. The most efficient map is an Array. So I add a "global" "static" counter in companion object to give each object unique id: object C { var id_counter = 0 } In primary constructor of C, with each creation of C I want to remember global counter ...

How do you verify that 2 copies of a VB 6 executable came from the same code base?

I have a program under version control that has gone through multiple releases. A situation came up today where someone had somehow managed to point to an old copy of the program and thus was encountering bugs that have since been fixed. I'd like to go back and just delete all the old copies of the program (keeping them around is a com...

Hi, I have a C hashing routine which is behaving strangely?

Hi, In this hashing routine: 1.) I am able to add strings. 2.) I am able to view my added strings. 3.) When i try to add a duplicate string, it throws me an error saying already present. 4.) But, when i try to delete the same string which is already present in hash table, then the lookup_routine calls hash function to get an index. ...

Do encryption algorithms require an internal hashing algorithm?

When I use C# to implement the AES symmetric encryption cipher, I noticed: PasswordDeriveBytes derivedPassword = new PasswordDeriveBytes(password, saltBytesArray, hashAlgorithmName, numPasswordIterations); Why do I need to use a hashing algorithm for AES encryption? Aren't they separate? Or is the hashing algorithm only used to create...

Lists Hash function

I'm trying to make a hash function so I can tell if too lists with same sizes contain the same elements. For exemple this is what I want: f((1 2 3))=f((1 3 2))=f((2 1 3))=f((2 3 1))=f((3 1 2))=f((3 2 1)). Any ideea how can I approch this problem ? I've tried doing the sum of squares of all elements but it turned out that there are ...

extendible hashing

I need to make a program that shows the hash value of a given key, using extendible hashing. In extendible hashing, I know that the buckets split and directories change. So if I make my program, do I have to already know things like if the bucket it hashes to is filled, or do I not have to worry about those things and just compute a has...

array size for extendible hashing

If I want to use extendible hashing to store a maximum of 100 records, then what is the minimum array size that I need? I am guessing that an array of 100 would be sufficient, but I could be wrong. I also suspect that I can use a smaller array. ...

PHP CRC32 length output

Hi! Is there anything that can make the returned length of the PHP CRC32 function to vary? Thanks! ...

How to go about signing text in a verifiable way from within ruby in a simple yet strong & portable way?

Guys, I have been looking for a portable method to digitally sign arbitrary text which can be placed in a document and distributed while maintaining its verifiable origin. Here is an example: a = 'some text' a.sign(<private key>) # => <some signature in ASCII format> The contents of a can now be distributed freely. If a receiver want...

How to create empty buckets in extendible hashing

I know how to do extendible hashing on paper, but I don't know how it's possible for empty buckets to be created. What would cause empty buckets to be created in extendible hashing? Can you show a simple example? ...

Safe non-tamperable URL component in Perl using symmetric encryption?

OK, I'm probably just having a bad Monday, but I have the following need and I'm seeing lots of partial solutions but I'm sure I'm not the first person to need this, so I'm wondering if I'm missing the obvious. $client has 50 to 500 bytes worth of binary data that must be inserted into the middle of a URL and roundtrip to their customer...

Converting text to bits (1's and 0's)

I'm implementing an MD-5 Hashing algorithm and I want to convert the text I have to bits so I can start manipulating them. As you know Hashing require taking block of bits and then manipulating them. There are many ways to do that but I can't determine the best/easiest way to just convert the text (string) into array of bits. Any clue ? ...

how to use hashed password in impersonate of ASP.NET

I have an ASP.NET application that requires impersonation as an administrator user. In web.config: <identity impersonate="true" userName="administrator" password="password"/> The customer complained about saving the password in clear text format. Is there a way to save the password here as hashed? ...

c# How to find if two objects are equal

Hi, I'm needing to know the best way to compare two objects and to find out if there equal. I'm overriding both GethashCode and Equals. So a basic class looks like: public class Test { public int Value { get; set; } public string String1 { get; set; } public string String2 { get; set; } public override int GetHashCode(...

Saving a MD5 hash of a text file into the same text file?

Today I read about MD5 hash and was wondering if this is possible. seems like a recursive problem... or is there a solution? ...

sha1sum duplicate files .

Can sha1sum return the same results for two files that are different ? I am asking this both from a theoretical and practical point of view. ...

hashing ISBN of a book

what would be a good way to hash the ISBN of a book? sorry for the confusion let me clarify, I want to hash the ISBN of books of size 1000. but the array might grow. its a hash table not encryption. the programming language is c but this is a general question. I want to know the standard hashing method for ISBN used in the industry or y...

Combining Java hashcodes into a "master" hashcode

I have a vector class with hashCode() implemented. It wasn't written by me, but uses 2 prime numbers by which to multiply the 2 vector components before XORing them. Here it is: /*class Vector2f*/ ... public int hashCode() { return 997 * ((int)x) ^ 991 * ((int)y); //large primes! } ...As this is from an establ...