A good cross platform hash function\algorithm

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Hey all,

I need a good hash function (for strings) that will produce the same hash value for a specific string on different platforms,

My app invovles a server farm, and a "bank" server,
Each server produces hash "keys" for strings and the bank stores the keys.
The Servers may later ask the bank if a specific key [hash value] exists in the bank and if so, do SomeThings() etc.

So the hash function hash to produce the same values on the bank server and on each of the servers on the farm (as well as PC who occasionally connect as clients and operate in a similar way to the servers on the farm.)

** All OS are windows (2k8_R2 or Win7) 64 bit

Thoughts:
- Will SHA-2, GetHashCode() or some other off-the-shelf standard, work well for me?
- Do I have to implement my own hash function in order to overcome the cross platform issue? if so, any recomendation for a good one.

Thanks a bunch,
Edo

Posted 25-Aug-12 21:15pm

Joezer BH

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AmitGajjar 26-Aug-12 4:25am

really sorry to say but if you do not have idea about all this then how can you build software for a bank ? apologies for asking you such a rude question.

Joezer BH 27-Aug-12 2:33am

Hi Amit,

Quite a language you have there, but that's fine.
I have an idea about those things but, there are ditch holes - e.g. using SHA with the .NET implementation turned out to give different values on different platforms (such as different OS, or 64\32 bit etc) and since the keys are generated on different platforms I need to know that the hashing algorithm provides identical values ON DIFFERENT PLATFORMS.

The "Bank" the the server holding the keys and objects related to those keys - hence "Bank" ...

The client has nothing to do with banking (as far as I know)
;)

AmitGajjar 27-Aug-12 2:39am

What if you are creating a service hosted on one platform and that will generate hash for you? in that case each time you will get identical key.

Joezer BH 30-Aug-12 6:54am

Conceptually that's a good idea @amitgajjar!
:)

However, not suiting for my situation :(
I am running a several minute computation on each server of my server farm over and over (several million times) with different params each time.
The set of params which is the string I need to hash, is not so short, so sending them over to the server to compute the hash will bottle-neck the server.

So I figures the guys here at CodeProject will give me a hand ;)

AmitGajjar 30-Aug-12 6:57am

if you do not want immediate hash value then you can call service with delayed call. create one xml file locally and after particular time call service for hashing all value inside xml. once you got hash data in xml, you can read it.

Joezer BH 30-Aug-12 7:02am

The Hash value is needed on-the-fly, as the server will be waiting for the "Bank" server's answer, to continue the computation.

We're off the main question's course, but you understand the environment in which I operate. The Hashing function thus has to be cross platform and good (near zero collision probability which is why I consider a 64 hash key).

Anyway, if nothing else I will compose my own hash function in the end...

AmitGajjar 30-Aug-12 7:05am

Creating your own hash function is the best option, you can use MD5,SHA adding salt and add some complex math functions will create some really strong hash key. i will be writing Article on it within a week. i will update you once done.

Joezer BH 30-Aug-12 7:07am

Cheers

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Kenneth Haugland · Answer 1 · 2012-08-26T01:16:00

Solution 1

How about the build in class in .NET:
http://msdn.microsoft.com/en-us/library/system.security.cryptography.rsacryptoserviceprovider.aspx[^]

Posted 26-Aug-12 1:16am

Kenneth Haugland

Comments

Espen Harlinn 26-Aug-12 8:11am

Implemented in both .Net and mono, good choice :-D

Kenneth Haugland 26-Aug-12 8:11am

Thanks Espen :)

Joezer BH 27-Aug-12 3:28am

Hi Kenneth,

I need a hashing function, does RSA provide this kind of functionality?
Hashing provides the ability to resemble a looooong string in a short key. That's what I need

e.g. a looooong set of configuration settings that is stored, in a bank,
when a client wishes to get this loooong set of configurations settings, it hashes them (and thus getting a short key that represents those settings, kind'a like CRC but not quite) with this short key, it can ask the "bank" server,

"Hey do you have the conf sett represented by the key 'aksdjhfalksjdhfalkjhf'?"

the problem with some hashing functions is (as I answered amitgajjar above) is that they don't always produce the same values on different platforms.
so for a single server they will be just fine, but for a system with many different platforms you'll have to do better ...