I input a XML file with UTF-8 encoding. I get the file length and hash the file, I write out the file and append the hash and length to the file.
I input this newly created file, extract the hash and length from it and then calculate the hash on data. When I view the data before and after hashing, they look the same, However, the hashes are coming up completely different.
Could someone look at my code and see where I may be makiong my mistake.
This will be a part of a bigger project that will be using memory streams. That is why I use a memorystream quite a bit in the code.
Thanks,
Chester
I input this newly created file, extract the hash and length from it and then calculate the hash on data. When I view the data before and after hashing, they look the same, However, the hashes are coming up completely different.
Could someone look at my code and see where I may be makiong my mistake.
VB.NET:
Private Sub CreateAppHash()
Dim encoder As New UTF8Encoding 'To encode the data
Dim SHA1 As New SHA1CryptoServiceProvider 'For hashing
Dim bytHash As Byte() 'To store the hash
bytHash = SHA1.ComputeHash(myFileMain) 'compute the hash (bytHash is a byte array)
Dim strHash As String = Convert.ToBase64String(bytHash) 'convert the hash to base 64
Dim bytHashes As Byte() 'To hold UTF-8 encoded hash
bytHashes = encoder.GetBytes(strHash) 'Convert hash to UTF-8
Dim myStream As New MemoryStream(myFileMain.Length) 'Create a memorystream to hold the data
myStream.Write(myFileMain, 0, myFileMain.Length) 'Copy the data to the memorystream (myfileMain is module
' level and has been filled with an XML UTF-8 encoded file
Dim length As Integer = myFileMain.Length 'Get length of memorystream
Dim strLen As String = CInt(length) 'convert length to string
strLen = strLen.PadLeft(30, "0") 'Make sure the length is 30 chracters long
Dim bytLen As Byte() = encoder.GetBytes(strLen) 'convert the length to UTF-8 bytes ans store in byte array
Dim fsOut As New FileStream(strOutFileArray3, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite)
Dim wr As New StreamWriter(fsOut) 'setup streamwriter to output data
wr.Write(encoder.GetString(myFileMain)) 'Convert byte array to string and write it to disk
wr.Write(encoder.GetString(bytHashes))
wr.Write(encoder.GetString(bytLen))
wr.Flush() 'Flush the streamwriter to make sure all data is written to disk
'////////////////////////////////////////////////////////////////////////////////////////////////////////////
'CHECK THE HASH
'Get the file with the Hash appended to it and put it in a byte array
Dim fsHashed As New FileStream(strOutFileArray3, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite)
Dim rdrHash As New StreamReader(fsHashed)
Dim bytHashed As Byte()
bytHashed = encoder.GetBytes(rdrHash.ReadToEnd)
Dim msLength As New MemoryStream(30) 'Set up memorystream to get the length of the original file
msLength.Write(bytHashed, bytHashed.Length - 30, 30)
'Dim bytLength As Byte()
Dim intLe As Integer = CInt(encoder.GetString(msLength.ToArray)) 'Convert original file length to integer
Dim myFi As New MemoryStream(intLe)
myFi.Write(bytHashed, 0, intLe) 'Get the file data minus file length with padding and hash code
'Output the extracted data to see how it looks
Dim fsOup As New FileStream("tester.txt", FileMode.OpenOrCreate, FileAccess.ReadWrite)
Dim rdrOP As New StreamWriter(fsOup)
rdrOP.Write(fsOup)
rdrOP.Flush()
Dim myhash As Byte() 'Setup to calculate hash on the extracted data
Dim strHasher As String
myhash = SHA1.ComputeHash(myFi) 'compute Hash on extracted data
strHasher = Convert.ToBase64String(myhash) 'Convert it to base 64
Dim bytHashs As Byte() = encoder.GetBytes(strHasher) 'encode hash to byte using UTF-8
Dim bytOld As Byte() 'To hash extracted from file data
Dim msO As New MemoryStream(100)
msO.Write(bytHashed, intLe, bytHashed.Length - 30 - intLe) 'Get hash from uploaded file
bytOld = msO.ToArray 'convert extracted hash to byte array
Dim strOlP, strNwP As String 'to compare extracted hash with newly calculated hash
strOlP = encoder.GetString(bytOld)
strNwP = encoder.GetString(bytHashs)
MessageBox.Show(strOlP & vbCrLf & vbCrLf & strNwP) 'Compare hashesThanks,
Chester
