Hash functions test data
Main intention and good quality of a hash function is its ability to distribute well the input data over the hash table.
When comes to testing of program using hash table it is not the problem to test with well distributed data. The problem is to test collisions under controlled circumstances.
We provide test data - sets of ASCII strings with the same hash value. Test data can be used in unit test or in robustness test where the program can be feed with several millions of collisions.
The hash functions we provide data for are described on the "Eternally Confuzzled - The Art of Hashing" web page.
The following hash functions are supported:
Here is a sample set of strings with the same jsw hash value, 0xbacabeee:
/space/quote-a/1/z_01hbacabeeehbayfxwdy /space/quote-a/2/z_02hbacabeeehafavqxth /space/quote-a/3/z_03hbacabeeehaaofzyxv
The prefixes, "/space/quote-a/1/"... are taken from the file. The second prefix "z_" also includes the unique identification of the string. The hash value, 0xbacabeee, is included into the string in hex form, i.e. surrounded by characters "h". The hash value can be included in decimal form (surrounded by character "d"):
/space/quote-a/1/z_01d3133849326dadaqoavx /space/quote-a/2/z_02d3133849326danjhiopi /space/quote-a/3/z_03d3133849326dagcrwlis
or not at all:
/space/quote-a/1/z_01aqttdwlg /space/quote-a/2/z_02agnsnbrh /space/quote-a/3/z_03aecdltvj
Prefixes can be excluded too:
z_01ahgvrnwv z_02bryqkfzb z_03adcsxblq
bqbgptwppk cebckkifu dnatcwnwnl
Up to ten millions strings with the same hash value (of the supported hash function) can be provided on request. Ask for price list.
This is the proof that above mentioned hash functions are not cryptographically safe. Hashes are actually broken by generating millions of test data with the same hash value.
If you use hashes as "unique" identification of certain data in your program (like file names, user names, user passwords,...), test data can help you see how your application can be broken. Use hash test data and improve your software!
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