How Do I hash a string as Hex instead of Text?

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Hello,

Been pulling my hair out trying figure out how to calculate the MD5 for a string of HEX characters. My code considers the input as text string, not hex string. How do I get VB to consider the string as HEX?

Here is the HEX string I want to calculate MD5 for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

MD5 for string as text = "A44D49B12BD10CDAF08A034638F8141B"
MD5 for string as hex = "E514481E8E3344F37A3F1E2BBFC84EEF"

Here is the code I have so far:

VB

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        hashblob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

        Using md5Hash As MD5 = MD5.Create()

            Dim hash As String = GetMd5Hash(md5Hash, hashblob2)
            Debug.Print(hash)
        End Using

    End Sub

    Shared Function GetMd5Hash(ByVal md5Hash As MD5, ByVal input As String) As String

        'Convert the input string to a byte array and compute the hash.
        Dim data = md5Hash.ComputeHash(Encoding.Default.GetBytes(input))

        ' Create a new Stringbuilder to collect the bytes
        ' and create a string.
        Dim sBuilder As New StringBuilder()

       ' Loop through each byte of the hashed data
        '' and format each one as a hexadecimal string.
        Dim i As Integer
        For i = 0 To data.Length - 1
            sBuilder.Append(data(i).ToString("X2"))
        Next i

       ' Return the hexadecimal string.
        Return sBuilder.ToString()

    End Function 'GetMd5Hash


Can anyone please tell me how to change my code to treat string as hex instead of text?

Appreciate any help or guidance!

Posted 17-Mar-14 3:38am

steveharan

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Comments

Sergey Alexandrovich Kryukov 17-Mar-14 10:07am

Your problem is that you are not formulating what do you want to achieve, so I'm not sure you really understand it by yourself. You just say "MD5 for string as hex = ...". What do you mean by that? Get numeric data represented by the string and hash this numeric data instead? You should understand, there is no such thing as "hex string" per se, you should explain what interpretation of that string is implied.
—SA

steveharan 17-Mar-14 10:16am

Sorry I did not articulate correctly. Yes I want to calc MD5 for a string containing many hex charecters. Do I need to create another string builder to convert the hex string to a byte array or something first?

Sergey Alexandrovich Kryukov 17-Mar-14 10:20am

There is no such thing as "hex character". The problem can be ambiguous. What is that data in the string? Sequence of bytes? Something else? By the way, how are you going to use this hash? In certain sense, it can be not important what form of data to you use to get hash. You would get different results, so what? It is important to know what would you use this hash for.
—SA

steveharan 17-Mar-14 10:48am

We have some equipment that returns the following string to the test station PC. We use the MD5 hex result to verify the data.
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
I need to calculate the MD5 for the string above, but my code process the data as string of text characters instead of a string of hex characters.
MD5 for string as text (current code returns this) = "A44D49B12BD10CDAF08A034638F8141B"
MD5 for string as hex (need code to return this) = "E514481E8E3344F37A3F1E2BBFC84EEF"

steveharan 17-Mar-14 11:00am

If I go to "http://www.fileformat.info/tool/hash.htm" and paste the string in the "string hash" field I get "A44D49B12BD10CDAF08A034638F8141B". If paste the string in the "binary hash" field I get "E514481E8E3344F37A3F1E2BBFC84EEF". How do I get my code to get same result as binary string?

Sergey Alexandrovich Kryukov 17-Mar-14 11:20am

You cannot just "verify the data". You can only compare one piece of data with another piece. What will you compare with what?

And you need to know how your "hex string" is interpreted. After all, each character in this string represents half-byte. You problem is to figure out how they are composed into bytes, in what order, create the array of bytes, parse each pair of half-bytes into a byte and fill in the array, then hash the array in a usual way.

—SA

steveharan 17-Mar-14 12:27pm

We have a master list of the MD5 values for all the datasets. So I retieve data from unit, calc md5 and then compare to table to confirm data is correct.

Sergey Alexandrovich Kryukov 17-Mar-14 13:09pm

You should simply see how the hash values were obtained and do exactly the same. Different representation of data dives different hash values. As simple as that. I think having stings in first place is just pointless. Why so many people these days work with strings representing data instead of data itself? This is nothing but a big flaw...
—SA

steveharan 17-Mar-14 13:17pm

So no way of tell my code to interpret string as hex characters instead of text characters? How does this site do it?

If I go to "http://www.fileformat.info/tool/hash.htm" and paste the string in the "string hash" field I get "A44D49B12BD10CDAF08A034638F8141B". If paste the string in the "binary hash" field I get "E514481E8E3344F37A3F1E2BBFC84EEF". How do I get my code to get same result as binary string?

3 solutions

Solution 1

There is no "tidy" way to do this: converting a hex string to a byte array isn't covered by the .NET framwork!

But it's not too complex:

C#

private static byte[] ConvertHex(string hex)
    {
    if (hex.Length % 2 == 1) throw new ArgumentException("The hexadecimal data cannot have an odd number of digits");

    int bytes = hex.Length / 2;
    byte[] result = new byte[bytes];
    int inputIndex = 0;
    for (int i = 0; i < bytes; i++)
        {
        result[i] = (byte)((GetHexNibble(hex[inputIndex++]) << 4) + (GetHexNibble(hex[inputIndex++])));
        }
    return result;
    }

private static int GetHexNibble(char hex)
    {
    if (hex <= '9') return hex - '0';
    return (hex - 'A') + 10;
    }

"I am just a tech with little programming skills, do not know C# at all... Can you send code in VB?

VB

Private Shared Function ConvertHex(hex As String) As Byte()
    If hex.Length Mod 2 = 1 Then
        Throw New ArgumentException("The hexadecimal data cannot have an odd number of digits")
    End If

    Dim bytes As Integer = hex.Length \ 2
    Dim result As Byte() = New Byte(bytes - 1) {}
    Dim inputIndex As Integer = 0
    For i As Integer = 0 To bytes - 1
        Dim hi As Integer = GetHexNibble(hex(inputIndex))
        inputIndex += 1
        Dim lo As Integer = GetHexNibble(hex(inputIndex))
        inputIndex += 1
        result(i) = CByte(hi * 4 + lo)
    Next
    Return result
End Function

Private Shared Function GetHexNibble(hex As Char) As Integer
    If hex <= "9"C Then
        Return hex - "0"C
    End If
    Return (hex - "A"C) + 10
End Function

Posted 17-Mar-14 5:45am

OriginalGriff

Updated 17-Mar-14 9:15am

v2

Comments

steveharan 17-Mar-14 12:22pm

I converted these two functions into VB, but I am getting a "Arithmetic operation resulted in an overflow for "result(i) = CByte((GetHexNibble(hex(System.Math.Max(System.Threading.Interlocked.Increment(inputIndex), inputIndex - 1))) << 4) + (GetHexNibble(hex(System.Math.Max(System.Threading.Interlocked.Increment(inputIndex), inputIndex - 1)))))"

Code:

Private Shared Function ConvertHex(ByVal hex As String) As Byte()
If hex.Length Mod 2 = 1 Then
Throw New ArgumentException("The hexadecimal data cannot have an odd number of digits")
End If

Dim bytes As Integer = hex.Length / 2
Dim result As Byte() = New Byte(bytes - 1) {}
Dim inputIndex As Integer = 0
For i As Integer = 0 To bytes - 1
result(i) = CByte((GetHexNibble(hex(System.Math.Max(System.Threading.Interlocked.Increment(inputIndex), inputIndex - 1))) << 4) + (GetHexNibble(hex(System.Math.Max(System.Threading.Interlocked.Increment(inputIndex), inputIndex - 1)))))
Next
Return result
End Function

Private Shared Function GetHexNibble(ByVal hex As Char) As Integer
If hex <= "9"c Then
Return hex & "0"c
End If
Return (hex & "A"c) + 10
End Function

OriginalGriff 17-Mar-14 13:25pm

I think you need to revisit C#: << and >> are shift operators. Try:
(GetHexNibble(hex[inputIndex++]) * 16)
instead and convert that.

steveharan 17-Mar-14 14:08pm

I am just a tech with little programming skills, do not know C# at all... Can you send code in VB?

OriginalGriff 17-Mar-14 15:15pm

Answer updated - silly language, VB! :laugh:

steveharan 17-Mar-14 15:29pm

Thank you soo much!

VB still has [prblem with the "-" charectars in the GetHexNibble function.

Private Shared Function GetHexNibble(hex As Char) As Integer
If hex <= "9"C Then
Return hex - "0"C
End If
Return (hex - "A"C) + 10
End Function

Tried to change as follows but get conversion error. "Conversion from string "CA" to type 'Double' is not valid."

Private Shared Function GetHexNibble(ByVal hex As Char) As Integer
If hex <= "9"c Then
Return hex & "0"c
End If
Return (hex & "A"c) + 10
End Function

Can you help once more?

OriginalGriff 17-Mar-14 16:02pm

Try:
Private Shared Function GetHexNibble(hex As Char) As Integer
If hex <= "9"C Then
Return hex - 48
End If
Return hex - 55
End Function

48 is the ASCII code for '0' and 65 is the ASCII code for 'A' (so take off the 10 so that VB doesn't have to and you get 55)

steveharan 17-Mar-14 16:07pm

VB still does not like the "-" characters, returns error: "Operator '-' is not defined for types 'Char' and 'Integer'."

OriginalGriff 18-Mar-14 5:40am

I hate VB.
I hate VB.
:laugh:

Private Shared Function GetHexNibble(hex As Char) As Integer
If hex <= "9"c Then
Return AscW(hex) - 48
End If
Return AscW(hex) - 55
End Function

OriginalGriff 17-Mar-14 16:04pm

BTW: Normally I'd test this stuff before I posted it, but I'm on a tablet at the moment and can't!

steveharan 17-Mar-14 16:08pm

NP, i REALLY appreciate the help! I feel like a moron...

OriginalGriff 17-Mar-14 16:30pm

You're not a moron.
Never confuse ignorance with stupidity: one of them can be cured! :laugh:
It's not a crime to not know something - well, not with me anyway... ;)

Matt T Heffron 18-Mar-14 20:27pm

Just for fun I wanted to see what the Linq solution would look like...
(without the GetHexNibble function)
Enjoy!
private static byte[] ConvertHex(string hex)
{
if (hex.Length % 2 == 1)
throw new ArgumentException("The hexadecimal data cannot have an odd number of digits");
bool inPhase = false;
byte[] result = hex.Zip(hex.Skip(1), (c1, c2) => {
inPhase = !inPhase;
return inPhase ? (byte?)byte.Parse(string.Concat(c1, c2), NumberStyles.AllowHexSpecifier) : (byte?)null;
}).Where(nb => nb != null).Select(nb => nb.Value).ToArray();
return result;
}

OriginalGriff 19-Mar-14 7:05am

There are all sorts of nasty ways you can do it with Linq! Here's one I found:
public static byte[] StringToByteArray(string hex)
{
return Enumerable.Range(0, hex.Length)
.Where(x => x % 2 == 0)
.Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
.ToArray();
}
And I'm proud to say I didn't write that! :laugh:

Solution 2

Hex code to byte array
--------------------------------------

C#

public static byte[] DecodeHex(string hextext)
{
   String[] arr = hextext.Split('-');
   byte[] array = new byte[arr.Length];
   for (int i = 0; i < arr.Length; i++)
         array[i] = Convert.ToByte(arr[i], 16);
   return array;
}

It guide you.
MD5 sample code for encrypt
-------------------------------------------

public static string Encrypt(string toEncrypt, bool useHashing, string imkey)
{
    byte[] keyArray;
    byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(toEncrypt);

    string key = imkey;
    if (useHashing)
    {
        MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
        keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
        hashmd5.Clear();
    }
    else
        keyArray = UTF8Encoding.UTF8.GetBytes(key);

    TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
    tdes.Key = keyArray;
    tdes.Mode = CipherMode.ECB;
    tdes.Padding = PaddingMode.PKCS7;

    ICryptoTransform cTransform = tdes.CreateEncryptor();
    byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
    tdes.Clear();
    return Convert.ToBase64String(resultArray, 0, resultArray.Length);
}

Posted 17-Mar-14 7:24am

SOHAM_GANDHI

Comments

steveharan 17-Mar-14 14:30pm

So I tried your code Soham and I get a overflow error "Value was either too large or too small for a UInt32." in the decodehex function.

Imports System.Security.Cryptography
Imports System.IO
Imports System.Text

Public Class Form1
Dim blob

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

blob = DecodeHex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

End Sub

Public Shared Function DecodeHex(ByVal hextext As String) As Byte()
Dim arr As [String]() = hextext.Split("-"c)
Dim array As Byte() = New Byte(arr.Length - 1) {}
For i As Integer = 0 To arr.Length - 1
array(i) = Convert.ToByte(arr(i), 16)
Next
Return array
End Function
Public Shared Function Encrypt(ByVal toEncrypt As String, ByVal useHashing As Boolean, ByVal imkey As String) As String
Dim keyArray As Byte()
Dim toEncryptArray As Byte() = UTF8Encoding.UTF8.GetBytes(toEncrypt)

Dim key As String = imkey
If useHashing Then
Dim hashmd5 As New MD5CryptoServiceProvider()
keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key))
hashmd5.Clear()
Else
keyArray = UTF8Encoding.UTF8.GetBytes(key)
End If

Dim tdes As New TripleDESCryptoServiceProvider()
tdes.Key = keyArray
tdes.Mode = CipherMode.ECB
tdes.Padding = PaddingMode.PKCS7

Dim cTransform As ICryptoTransform = tdes.CreateEncryptor()
Dim resultArray As Byte() = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length)
tdes.Clear()
Return Convert.ToBase64String(resultArray, 0, resultArray.Length)
End Function

End Class

SOHAM_GANDHI 17-Mar-14 14:45pm

Pass string as 46-46-45-36 as on..
46 is get convert to byte.

Error because.
it convert to byte as single number like 4 ,6 ,4, 6 , . . .

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steveharan · Accepted Answer · 2014-03-18T13:26:00

Just in case some other poor sap needs help doing this in VB, I figured out the solution with the help of a good friend and positive feedback from OriginalGriff!

I must admit the initial ARROGANT responses I received were extremely discouraging and unnecessary...

VB CODE:

Public Function HexDecode(ByVal s As String) As Byte()
Return HexDecode(s, 0)
End Function

Public Function HexDecode(ByVal s As String, ByVal paddingBytes As Integer) As Byte()
If s Is Nothing Then
Throw New ArgumentNullException("s")
End If

If s.IndexOf(":"c) > -1 Then
s = s.Replace(":", "")
End If

If (s.Length Mod 2) <> 0 Then
Throw New FormatException("parameter 's' must have an even number of hex characters")
End If

Dim result As Byte() = New Byte(s.Length \ 2 + (paddingBytes - 1)) {}
For i As Integer = 0 To result.Length - paddingBytes - 1
result(i) = Byte.Parse(s.Substring(i * 2, 2), NumberStyles.AllowHexSpecifier)
Next
Return result
End Function

Thanks to everyone who pointed me in the right direction!

Cheers

How Do I hash a string as Hex instead of Text?

3 solutions

Solution 1

Solution 3

Solution 2

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