Re: MD5 algorithm issue - C# Discussion Boards

George_George10-Jan-09 2:23

10-Jan-09 2:23

Hi Abhijit,

It is legacy system interface limitation. It has to use 32-bit int. Any ideas to convert a string into 32-bit int? The best idea I could think of is to calculate hashing for the input string. But the hashing result is not 32-bit, so I am thinking about how to convert it...

Any comments or ideas?

regards,
George

DaveyM696-Jan-09 10:55

DaveyM69

6-Jan-09 10:55

Don't know if you've sorted this or not George but thought I'd throw in my 2c worth.

As you know MD5 is 128bit (16 bytes) so there's no way of getting a unique value into an Int32. The same applies to Int64.GetHashCode() method - if you test it, you'll find you will get identical results for different values as it's impossible to make 64 fit into 32.

There are 32 bit hash algorithms out there - if it's just for file checking etc then it will be good enough, but if it's for security then forget it. If it's just for the sake of turning an arbitary string into an int then use GetHashCode() on your string.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

George_George10-Jan-09 2:21

10-Jan-09 2:21

Thanks Dave,

I can not use GetHashCode because for different CLR versions, the same content will return different results.

I think if there could be a hashing algorithm which returns 32-bit result, it will be great! But I can not find a built-in one in CLR library. Do you know whether there is a built-in one?

regards,
George

DaveyM6910-Jan-09 8:36

DaveyM69

10-Jan-09 8:36

Have a look at this[^]. Be sure to check out the very last coment on the page as it could be important.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

Jon Rista6-Jan-09 14:40

Jon Rista

6-Jan-09 14:40

Perhapse this?

string a = "Input String";

MD5 crypto = MD5.Create();
byte[] rawHash = crypto.ComputeHash(UTF32Encoding.Default.GetBytes(a));
Guid guid = new Guid(rawHash);
int hash = guid.GetHashCode();

George_George10-Jan-09 2:25

10-Jan-09 2:25

Hi Jon,

Sorry I can not use GetHashCode because different CLR version will return different result for GetHashCode for the same input content.

Any comments or other new ideas? Smile | :)

regards,
George

Jon Rista10-Jan-09 13:24

Jon Rista

10-Jan-09 13:24

You can generate your own hash:

string a = "Input String";

MD5 crypto = MD5.Create();
byte[] rawHash = crypto.ComputeHash(UTF32Encoding.Default.GetBytes(a));
Guid guid = new Guid(rawHash);

int hash = 0;

for (int i=0; i<16; i+=4)
{
    hash ^= (rawGuid[i] << 24) | (rawGuid[i+1] << 16) | (rawGuid[i+2] << 8) | rawGuid[i+3];
}

return hash;

Who is coneected with My Mechine

Hamid_RT15-Jan-09 2:24

Hamid_RT

15-Jan-09 2:24

See How to get MD5 hash in C# . NET[^].

Of one Essence is the human race
thus has Creation put the base
One Limb impacted is sufficient
For all Others to feel the Mace
(Saadi )

SQL Merge

ellllllllie5-Jan-09 23:03

ellllllllie

5-Jan-09 23:03

hello,
i have created a setup for my application that instance a database into sql server.
when adding some features to my project i have changed some tables and some columns in my database.
My problem is that: how to update the database in my setup without overwriting the existing database and also do not losing the data.
any help is appreciated.
regards

dghdfghdfghdfghdgh

Re: SQL Merge

Wendelius5-Jan-09 23:42

Wendelius

5-Jan-09 23:42

Instead of installing a database during an upgrade setup you should create a script which adds/updated/removes the rows/columns/tables to datatabase.

The need to optimize rises from a bad design.My articles[^]

Re: SQL Merge

SeMartens5-Jan-09 23:44

SeMartens

5-Jan-09 23:44

Hi ellie,

you could try to use a sql-script that looks like this:

<br />
 IF NOT EXISTS (SELECT COLUMN_NAME FROM syscolumns WHERE COLUMN_NAME = 'MyColumn') THEN<br />
   ALTER TABLE ADD COLUMN MyColumn varchar(256) NULL;<br />
 END IF<br />

You can use this style for tables, triggers, columns etc.

During your installation you can execute this script.

Hope this helps you.

Regards
Sebastian

P.S.: Be sure to modify the sql-code above to the grammar of your sql server.

It's not a bug, it's a feature!

Me in Softwareland.

nidheeshkayal5-Jan-09 22:52

nidheeshkayal

5-Jan-09 22:52

Hi all,

I need to create an application thru coding which will pop up when a user trying to establish a connection with my mechine.

Is there any way to do this

Language : C#.net

Thanx

Nidheesh

Re: Who is coneected with My Mechine

rah_sin5-Jan-09 23:24

rah_sin

5-Jan-09 23:24

Yes there is very easy way to do it
Step 1. Search on google.
Step 2. Start coding.
$Shucks | :-\$

rahul

Re: Who is coneected with My Mechine

nidheeshkayal5-Jan-09 23:51

nidheeshkayal

5-Jan-09 23:51

thanx Rahul...

Re: Who is coneected with My Mechine

EliottA6-Jan-09 2:01

EliottA

6-Jan-09 2:01

"Another" one automation error...

Member 28952165-Jan-09 22:29

Member 2895216

5-Jan-09 22:29

Hello all,

There is some C# 2005 component that I want to use from VB6.
C# DLL registered for COM interop.
If I run VB application as stand-alone all works fine.
If I want to debug an application from VB IDE I get an "automation error" on NEW with error code -2146233036(80131534).

All sagestions appreciated...

Simon P Stevens5-Jan-09 23:01

Simon P Stevens

5-Jan-09 23:01

When you run in the IDE, your app's path is effectively c:\Program Files\Microsoft Visual Studio\VB98\VB6.EXE. This means it will search for the dll in the VB98 directory. Try placing your dll here. Or adding a environment variable "devpath" to point to the dlls location.

Simon

Member 28952165-Jan-09 23:16

Member 2895216

5-Jan-09 23:16

Simon, thank you for replay!

I have solved this issue exectly as you proposed: placed all referenced assemblies in VB6's directory.
But I don't understand why it looking for them there... I checked CurDir and in debug time it's a my application EXE directory, rather than VB's directory.
So, VB6.EXE loads my application exe; looks in registry for COM interop; loads a TLB from my application directory and ....? How it comes back to VB6's directory?

Simon P Stevens5-Jan-09 23:34

Simon P Stevens

5-Jan-09 23:34

Check the App.Path rather than the CurDir. You'll find it's set to the VB98 directory.

Don't quote me on this, but my guess is you've got your order wrong. This is my guess at what is going on.
1) VB6 loads app exe.
2) Sees requirement for external assembly reference.
3) Searches App.Path location for required assembly.
4) Assembly found, and read, TLB required so check registry.
5) TLB location read from registry.
6) TLB loaded.

In .net you can use the Fusion log viewer[^] to monitor assembly bindings and searched locations as they are loaded. I don't know if it works when the assembly is being loaded by VB6 though.

Simon

XML attribute issue during desrialize

Member 28952166-Jan-09 0:16

Member 2895216

6-Jan-09 0:16

and again thank you for fast replay Smile | :)

!
and for VERY helpfull tool (yep, seems it's monitoring entire CLR activity, so an interop activity as well).

George_George5-Jan-09 21:55