Re: connection string in a file - C# Discussion Boards

File Byte[] Conversion to String for MD5 Hash Generation

19-Jun-09 4:33

Alright up to you, you're just making it harder though

JimmyHeaddon19-Jun-09 3:39

JimmyHeaddon

19-Jun-09 3:39

Hello!

I am trying to write an app that will read a file and generate an RFC 1321 compliant MD5 hash.

I have read a number of tutorials online and have been able to generate a compliant MD5 hash from a string, but I need to be able to pass my app a file and say "what is the MD5 hash of this file?".

Apparently I can read the file in to a byte array and then convert this to a string that my MD5 hash generator can read.

So far I have hit 2 problems:

- My byte[] conversion to string is resulting in an incorrect MD5 hash to all the web generators I have tried.
- I cannot read the byte[] of a file over 2 gigabytes (a buffering is needed I'm told?).

Any chance someone could help me out here? Ignore the part where I am setting the textbox.text value this was just for debug!

private void button1_Click(object sender, EventArgs e) {
   // Read File byte[] And Convert To String
   Byte[] byteArray = File.ReadAllBytes("C:\\ITV-9C-28225-C.xml");
   String stringFromByteArray = Convert.ToBase64String(byteArray);

   // Return The MD5 Hash Value
   textBox2.Text = MD5Hash(stringFromByteArray);
}

// Generate MD5 Hash Value
public static string MD5Hash(string text) {
   System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
   return System.Text.RegularExpressions.Regex.Replace(BitConverter.ToString(md5.ComputeHash(ASCIIEncoding.Default.GetBytes(text))), "-", "");
}

Cheers in advance!

Re: File Byte[] Conversion to String for MD5 Hash Generation

harold aptroot19-Jun-09 3:45

Re: File Byte[] Conversion to String for MD5 Hash Generation [modified]

19-Jun-09 3:45

Well no wonder, you first make it into base64, and then use that as raw bytes - that does not make any sense in any way.
If you want to use ReadAllBytes, then at least pass the bytes to the MD5 object as bytes. Or if you have to use base64, decode it first
System.Security.Cryptography.MD5 has a ComputeHash which takes a Stream as argument.

Mirko198019-Jun-09 4:02

Mirko1980

19-Jun-09 4:02

Why you are converting the byte array into a base-64 string and then calculating the hash on the string? You can calculate the hash directly on the byte array, probably that is the reason because your hash in incorrect.
Also, why you are using Regex.Replace instead of the regular string.Replace?

For your 2nd problem, you can calculate the hash on a stream instead than on a byte array (that has a limit of 2Gb).

The following code summarizes what you have to do:

public static string MD5Hash(string filename)
{
    System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();

    using (Stream stream = new FileStream(filename, FileMode.Open, FileAccess.Read))
    {
        return BitConverter.ToString(md5.ComputeHash(stream)).Replace("-", "");
    }    
}

Much simpler, don't you think? Wink | ;)

modified on Friday, June 19, 2009 10:19 AM

Re: File Byte[] Conversion to String for MD5 Hash Generation

JimmyHeaddon19-Jun-09 4:27

JimmyHeaddon

19-Jun-09 4:27

Fantastic! Thank you so much for your help everyone this is working lovely Smile | :)

Re: File Byte[] Conversion to String for MD5 Hash Generation

Luc Pattyn19-Jun-09 4:02

Luc Pattyn

19-Jun-09 4:02

Hi,

as Harold said, just do:

MD5CryptoServiceProvider p=new MD5CryptoServiceProvider();
using (FileStream stream=new FileStream(filename, FileMode.Open, FileAccess.Read)) {
    byte[] hash=p.ComputeHash(stream);
    ...
}

Luc Pattyn [Forum Guidelines] [My Articles]

DISCLAIMER: this message may have been modified by others; it may no longer reflect what I intended, and may contain bad advice; use at your own risk and with extreme care.

connection string in a file

Adekolurejo19-Jun-09 3:38

Adekolurejo

19-Jun-09 3:38

Please I need help on this problem.
I have an application am writing using visual c# 2008. The isuse is this I want connection string to the database to be read from a file save elsewhere on the system because after package and installation of the application if there is any changes in the connection parameter i will just change it in the file insted of changing it in the code and package it again. Onformload, he read the connection file and connect to database.
Thanks
Ademola

SeMartens19-Jun-09 3:44

SeMartens

19-Jun-09 3:44

Did you ever heard of the App.config? Click on your project in VS, select "Add new element" and choose "application settings file" from the dialog. You can access the config with System.Configuration.ConfigurationManager.ConnectionStrings.

Have a look here: http://www.ezzylearning.com/tutorial.aspx?tid=8067328[^]

Regards
Sebastian

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

Check out my CodeProject article Permission-by-aspect.

Me in Softwareland.

stancrm19-Jun-09 3:47

stancrm

19-Jun-09 3:47

And the question ist ??

I think, what you need is how to write the connection string to a file, is that write ?

When yes, then use :
string connectionString = "...abc...";
File.WriteAllText(@"c:\myfile.txt", connectionString);

string connectionString = File.ReadAllText(@"c:\myfile.txt");

You must also encrypt your connection string before write it to a file.
You don't want anybody to know your database password, do you ?.. Smile | :)

harold aptroot19-Jun-09 4:00

19-Jun-09 4:00

stancrm wrote:
You must also encrypt your connection string before write it to a file.
You don't want anybody to know your database password, do you

You can't make it impossible. If you encrypt it, well, your program would contain the code to decrypt it. And they will have that code.
The same problem applies to all local data and is impossible to solve, though you could make the chain of encrypted keys of arbitrary length to slow the attacker down.

Edit (used to be something here about encrypted connection strings): scratch that, it's just impossible as well. Great. So now we know you don't even need to try to hide your connection string, at least that saves us all some effort.

Adekolurejo19-Jun-09 4:30

Adekolurejo

19-Jun-09 4:30

File.WriteAllText(@"c:\myfile.txt", connectionString);

string connectionString = File.ReadAllText(@"c:\myfile.txt");

thanks but File will be declare as what in this context?

harold aptroot19-Jun-09 4:34

19-Jun-09 4:34

You don't declare File, it already exists.

Re: connection string in a file [modified]

meeram39519-Jun-09 3:48

meeram395

19-Jun-09 3:48

Probably this may help you.

Success is the good fortune that comes from aspiration, desperation, perspiration and inspiration.

kstls20-Jun-09 11:03

kstls

20-Jun-09 11:03

I would use App.config aswell as SeMartens describes, but if you prefer to use a seperate file other than App.config, why not make the main program retrieve the connectionstring from a seperate class with a static method and just have that as a dll file. Then if the connectionstring should change you only have to replace the dll with a new one. Smile | :)

modified on Saturday, June 20, 2009 5:15 PM

Urgent Mail Sending Problem

dev sheoran19-Jun-09 2:09

dev sheoran

19-Jun-09 2:09

Hi,
I am sending emails with attachment(.txt file) using c#.
I read data from database saved as varchar datatype. I read data in memory stream and output the memory stream as attachment with content type text(.txt file).

It sends emails to gmail, yahoo,hotmail,rediff etc. mail servers with attachment(which is a .txt file) perfectly fine.
(It means there is no problem with code)

But when i send emails to my own mail server it skips the attachment i.e. i get the emails without attachment.

Please help me asap.
What could be the reason?

My mail server IP is 72.9.144.139

Thanks,
Dev

Not Active19-Jun-09 2:13

Not Active

19-Jun-09 2:13

1) Don't mark your post as Urgent, it's rude and will not get any attention from those who could best help

2) Don't include your server IP address on a public forum. Unless you want your mail server to be used for sending spam.

Could it be that your server is blocking the attachments?

only two letters away from being an asset

dev sheoran19-Jun-09 2:30

dev sheoran

19-Jun-09 2:30

Thanks for your precious suggestions.

We use to send emails with attachment to and from our mail server.
We get emails with attachment from other mail servers also.
I don't think that our server is blocking attachment.

Re: Urgent Mail Sending Problem [modified]

Nagy Vilmos19-Jun-09 3:22

Nagy Vilmos

19-Jun-09 3:22

You thank for help and yet leave the ip address. Interesting.

Panic, Chaos, Destruction.
My work here is done.

musefan19-Jun-09 3:24

musefan

19-Jun-09 3:24

The edit button is commonly overlooked by new CP members Wink | ;)

SEE THIS IS AN EDIT:

Now all he needs to do is edit his OP and remove IP Address: [REMOVED] so no one can see it...

Oops Laugh | :laugh:

Life goes very fast. Tomorrow, today is already yesterday.

modified on Friday, June 19, 2009 9:38 AM

EliottA19-Jun-09 3:38

EliottA

19-Jun-09 3:38

Why make it worse by highlighting the fact he left his mail server IP address, not that it's anything important or useful to the outside world, it can be resolved with a DNS request. But either way, why repeat it and take attention to his error?

Check out the CodeProject forum Guidelines[^]
The original soapbox 1.0 is back![^]

musefan19-Jun-09 3:40

musefan

19-Jun-09 3:40

I'm just playing with him, and if the error was not pointed out then how would he know not to do it in the future?

Life goes very fast. Tomorrow, today is already yesterday.