I have two strings:
Dim Original_Hex_Bytes as string = "616572646E61"
Dim Patched_Hex_Bytes as string = "616E64726561"
Then I have a binary file and I need to search for the Original_Hex_Bytes and replace them with Patched_Hex_Bytes; I don't konw the offset where begin to write new bytes :(
How can I do this?
If needed, I also know how to convert Hex strings in bytes, I use this:
Private Function Hex_To_Bytes(ByVal strinput As String) As Byte()
Dim i As Integer = 0
Dim x As Integer = 0
Dim bytes(strinput.Length / 2) As Byte
Do While (strinput.Length > i + 1)
Dim lngDecimal As Long = Convert.ToInt32(strinput.Substring(i, 2), 16)
bytes(x) = Convert.ToByte(lngDecimal)
i += 2
x += 1
Loop
Return bytes
End Function
You can use BinaryReader and BinaryWriter classes to achieve this.
But in this case, as you do not know the file structure, need to read the entire file and sweep it in search of bytes array and will be easier to use ASCII strings as aerdna and andrea.
When you know the structure of a file is more appropriate to work with data structure to manipulate its contents.
Related
I have a byte array need to convert to integer, and this array only have one value. I tried Bitconverter, convert.ToInt32 both are not working for me. my code as follows:
Dim a As new Byte() ={&H1C} ' the value range is {&H01} to {&HFF}
Dim key As integer = BitConverter.ToInt32(a,1)
I need the result with key = 28, which convert function I should use?
Thank you very much.
BitConverter.ToInt32 needs 4 bytes to work with, so you just need to put your one byte value into a 4 byte array. Allowing for the endianness, something like this:
Dim a() As Byte = { &H1C }
Dim b(3) As Byte
If BitConverter.IsLittleEndian Then
b(0) = a(0)
Else
b(3) = a(0)
End If
Dim key As Integer = BitConverter.ToInt32(b, 0)
You are not converting an array of values, but rather a single array element.
That said, there is no need to call a conversion function to convert a single Byte to an Integer. Just assign the value.
Dim key As Integer = a(0)
How are you?
I wrote a program manipulating big binary chains (string variables). This said manipulation requires me to store my chains in a variable so I can use them as numbers. The only variable type that I have found big enough to store such lengthy numbers is BigInteger (we are talking 1.0E100+).
I would like to use something like:
val = BigInteger.Parse(bin, 2)
But the second parameter needed is a NumberStyles object, which can only refer to a NumberStyles.HexNumber.
Is there a simple/optimal way to do this?
Thank you very much. :)
This converts a binary string to BigInteger in 8 bit chunks. It assumes that the binary string represents a positive number.
Private Function BinToBI(ByRef binstr As String) As BigInteger
Dim t As New List(Of Byte)
Dim s As String
Dim idx As Integer = binstr.Length
Do While idx > 0
'get 8 bits
If idx >= 8 Then
s = binstr.Substring(idx - 8, 8)
Else
s = binstr.Substring(0, idx).PadLeft(8, "0"c)
End If
'convert to byte and add to list
Dim b As Byte = Convert.ToByte(s, 2)
t.Add(b)
idx -= 8
Loop
'force to positive
If t(t.Count - 1) >= 128 Then
t.Add(0)
End If
Dim rv As New BigInteger(t.ToArray)
Return rv
End Function
for testing
Dim d As Double = 1.0E+101
Debug.WriteLine(d.ToString("n2"))
Dim bi As BigInteger
' Dim bin As String = "1111111111111111111111111111111" 'Integer.MaxValue
' Dim bin As String = "111111111111111111111111111111111111111111111111111111111111111" 'Long.MaxValue
Dim bin As String = "1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111110"
bi = BinToBI(bin)
Debug.WriteLine(bi.ToString("n2"))
This was not well tested but should give you some ideas.
I have a selection of docx files stored as blob data in hexadecimal, I need to retrieve these so I can access the text within.
So far, I have converted the hex to string format with the following:
Dim blob = BLOB DATA
Dim con As String = String.Empty
For x = 2 To st.Length - 2 Step 2
con &= ChrW(CInt("&H" & st.Substring(x, 2)))
Next
However, if I then save the output from this as a .docx the file will not open because it is 'corrupt'. I presume that is why when I load this string into a memorystream and then try and use Novacode.DocX.Load(memoryStream) it gives me a similar corruption error.
I have tried splitting to byte array in two fashions, both give me different results.
System.Text.Encoding.Default.GetBytes(hex)
I have also tried.
Public Function HexToByteArray(hex As String) As Byte()
Dim upperBound As Integer = hex.Length \ 2
If hex.Length Mod 2 = 0 Then
upperBound -= 1
Else
hex = "0" & hex
End If
Dim bytes(upperBound) As Byte
For i As Integer = 2 To upperBound
bytes(i) = Convert.ToByte(hex.Substring(i * 2, 2), 16)
Next
Return bytes
End Function
I then tried converting them both to a memory stream and using them to create a DocX object like so:
Dim doc As DocX = DocX.Load(New MemoryStream(bytes))
docx is not a text format, it's a binary format. Thus, converting it to a string is just plain wrong. Your end result needs to be a byte array.
Knowing that, your problem can be split into two simpler problems:
Split your hex string into strings of two characters each. See this SO question for details (or keep your existing loop, which is perfectly fine):
How to split a string by x amount of characters
Convert those "small" strings, which contain the hexadecimal representation of a byte, into bytes. See this SO question for details:
How do I convert a Hexidecimal string to a Byte Array?
Combining those two solutions is left as an exercise to the reader. We don't want to spoil all the fun or ruin the learning experience. ;-)
I have a function which converts string to an array of bytes. If the string is written in English, the function works fine. But if the input string is Arabic, the function doesn't return, and I get this error:
Value was either too large or too small for an unsigned byte
Friend Function StringtoByteArray(ByRef value As String) As Byte()
Dim temp() As Byte
ReDim temp(Len(value) - 1)
Dim i As Integer
For i = 0 To Len(value) - 1 Step 1
temp(i) = Convert.ToByte(Convert.ToChar(Mid(value, i + 1, 1)))
Next
StringtoByteArray = temp
End Function
What should I change to convert Arabic characters to byte?
I am using VB.NET.
You don't need to write your function for that, this should work:
Dim b As Byte() = System.Text.Encoding.Unicode.GetBytes(value)
I have read bytes from file and I have to get a String from known location.
Dim b() As Byte = File.ReadAllBytes("MYFILE.BIN")
Dim myYear As String = Encoding.ASCII.GetString(b)
That gives whole file in myYear String so I can extract a year from there.
Is there some handy and shortest way to get bytes from 50 to 54 and convert only that part to string?
Maybe something like the following. Its not shorter but you don't need to read the complete file into memory.
Using stream = File.OpenRead("c:\MYFILE.BIN")
stream.Seek(50, SeekOrigin.Begin)
Dim b = New Byte(4) {}
stream.Read(b, 0, 5)
Dim str = Encoding.ASCII.GetString(b)
End Using