C# Problem using blowfish NET: How to convert from Uint32[] to byte[]

Question

In C#,I'm using Blowfish.NET 2.1.3's BlowfishECB.cs file(can be found here)

In C++,It's unknown,but it is similiar.

In C++,the Initialize(blowfish) procedure is the following:

void cBlowFish::Initialize(BYTE key[], int keybytes)

In C#,the Initialize(blowfish) procedure is the same

public void Initialize(byte[] key, int ofs, int len)

This is the problem:

This is how the key is initialized in C++

DWORD keyArray[2] = {0}; //declaration
...some code
blowfish.Initialize((LPBYTE)keyArray, 8);

As you see,the key is an array of two DWORDS,which is 8 bytes total.

In C# I declare it like that,but I get an error

BlowfishECB blowfish = new BlowfishECB();
UInt32[] keyarray = new UInt32[2];
..some code
blowfish.Initialize(keyarray, 0, 8);

The error is:

Argument '1': cannot convert from 'uint[]' to 'byte[]'

What am I doing wrong?

Thanks in advance!

This question is interesting not only for apps that use Blowfish, but for any app that needs to do data manipulation to convert between types of arrays. — Cheeso, Mar 28 '09 at 22:22

Reed Copsey · Accepted Answer · 2009-03-28T14:41:50.353

5

You can use BitConverter to get the bytes from a UInt32.

To do this, you'll need to convert each element in a loop. I would do something like:

private byte[] ConvertFromUInt32Array(UInt32[] array)
{
    List<byte> results = new List<byte>();
    foreach(UInt32 value in array)
    {
        byte[] converted = BitConverter.GetBytes(value);
        results.AddRange(converted);
    }
    return results.ToArray();
}

To go back:

private UInt32[] ConvertFromByteArray(byte[] array)
{
    List<UInt32> results = new List<UInt32>();
    for(int i=0;i<array.Length;i += 4)
    {
        byte[] temp = new byte[4];
        for (int j=0;j<4;++j)
            temp[j] = array[i+j];
        results.Add(BitConverter.ToUInt32(temp);
    }
    return results.ToArray();
}

edited Mar 28 '09 at 14:41

answered Mar 28 '09 at 14:10

Reed Copsey

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@Reed Copsey,I tried it,but It gets even worse: Argument '1': cannot convert from 'uint[]' to 'double' It's an array of UInt,not Uint. – Ivan Prodanov Mar 28 '09 at 14:21
JaredPar's option is a nice option if you're using C# 3 and linq. – Reed Copsey Mar 28 '09 at 14:26
I'm using C# with C# 2008 Express SP1 ,but I get error there too. – Ivan Prodanov Mar 28 '09 at 14:28
@John: The code in my edit should work... what error are you receiving? – Reed Copsey Mar 28 '09 at 14:29
@Reed Copsey, Thanks! I'm trying it right now,but can you add a function that converts from byte[] to Uint[] aswell? The same 8 bytes should be converted into a UInt[] array with 2 members as its in the source code. – Ivan Prodanov Mar 28 '09 at 14:36

score 4 · Answer 2 · edited Jan 24 '12 at 21:35

4

If you are using VS2008 or C# 3.5, try the following LINQ + BitConverter solution

var converted = 
  keyArray
    .Select(x => BitConverter.GetBytes(x))
    .SelectMany(x => x)
    .ToArray();

Breaking this down

The Select converts every UInt32 into a byte[]. The result is an IEnumerable<byte[]>
The SelectMany calls flattes the IEnumerable<byte[]> to IEnumerable<byte>
ToArray() simply converts the enumerable into an array

EDIT Non LINQ solution that works just as well

List<byte> list = new List<byte>();
foreach ( UInt32 k in keyArray) {
  list.AddRange(BitConverter.GetBytes(k));
}
return list.ToArray();

edited Jan 24 '12 at 21:35

Mark Lakata

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answered Mar 28 '09 at 14:22

JaredPar

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@JaredPar I get this error: 'System.Array' does not contain a definition for 'Select' and no extension method 'Select' accepting a first argument of type 'System.Array' could be found (are you missing a using directive or an assembly reference?) //end error – Ivan Prodanov Mar 28 '09 at 14:26
@John, are you using VS2005 or VS2008? If 2008, make sure you add using System.Linq to the top of the file. If not, I'll update for a VS2005 solution – JaredPar Mar 28 '09 at 14:27
@John: You can use my code (which does the same), or reference System.Linq and use C# 3 / VS 2008. – Reed Copsey Mar 28 '09 at 14:27
@Reed Copsey,I'll try your code,but I might need a function that converts byte[] to Uint32[] ,because below this code I call blowfish.Encode @JaredPar,I'm very new to C#,my previous language is Delphi and I cannot get used to C#.I'm using C# Express 2008.Could you explain step by step what to do. – Ivan Prodanov Mar 28 '09 at 14:33
@John, if you're using C# Expression 2008, either solution should work. If the first one is not working, go to the top of the file and make sure that you have a line saying using System.Linq; – JaredPar Mar 28 '09 at 14:36
@JaredPar, Thank you too,could you give a solution how to eventually turn those 8 bytes back into an array of Uint32? Non LINQ solution would be better,because im new. – Ivan Prodanov Mar 28 '09 at 14:41
@John: I added it to my answer for you. – Reed Copsey Mar 28 '09 at 14:42
Ok.You both know too much,I digged up both answers.@Reed Copsey - yours is the one I accepted,but I want to Thank JaredPar too.Thank you guys! – Ivan Prodanov Mar 28 '09 at 14:46
@Jared - you can make the non-LINQ solution even more concise by using Array.ForEach(). – Cheeso Mar 28 '09 at 22:21

score 0 · Answer 3 · edited May 23 '17 at 10:32

0

If you need a faster way to convert your value types, you can use the hack I described in the following answer: What is the fastest way to convert a float[] to a byte[]?

This hack avoid memory allocations and iterations. It gives you a different view of your array in O(1).

Of course you should only use this if performance is an issue (avoid premature optimization).

edited May 23 '17 at 10:32

Community

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answered Mar 12 '12 at 11:43

Omer Mor

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C# Problem using blowfish NET: How to convert from Uint32[] to byte[]

3 Answers3