Encrypting or Decripting a file using VB.net 2005

Dim strFileToEncrypt As String
Dim strFileToDecrypt As String
Dim strOutputEncrypt As String
Dim strOutputDecrypt As String
Dim fsInput As System.IO.FileStream
Dim fsOutput As System.IO.FileStream
'Current Index
Public lstIndex As Int16
'*************************
'** Create A Key
'*************************
Public Function CreateKey(ByVal strPassword As String) As Byte()
'Convert strPassword to an array and store in chrData.
Dim chrData() As Char = strPassword.ToCharArray
'Use intLength to get strPassword size.
Dim intLength As Integer = chrData.GetUpperBound(0)
'Declare bytDataToHash and make it the same size as chrData.
Dim bytDataToHash(intLength) As Byte
'Use For Next to convert and store chrData into bytDataToHash.
For i As Integer = 0 To chrData.GetUpperBound(0)
bytDataToHash(i) = CByte(Asc(chrData(i)))
Next
'Declare what hash to use.
Dim SHA512 As New System.Security.Cryptography.SHA512Managed
'Declare bytResult, Hash bytDataToHash and store it in bytResult.
Dim bytResult As Byte() = SHA512.ComputeHash(bytDataToHash)
'Declare bytKey(31). It will hold 256 bits.
Dim bytKey(31) As Byte
'Use For Next to put a specific size (256 bits) of
'bytResult into bytKey. The 0 To 31 will put the first 256 bits
'of 512 bits into bytKey.
For i As Integer = 0 To 31
bytKey(i) = bytResult(i)
Next
Return bytKey 'Return the key.
End Function

Public Function CreateIV(ByVal strPassword As String) As Byte()
'Convert strPassword to an array and store in chrData.
Dim chrData() As Char = strPassword.ToCharArray
'Use intLength to get strPassword size.
Dim intLength As Integer = chrData.GetUpperBound(0)
'Declare bytDataToHash and make it the same size as chrData.
Dim bytDataToHash(intLength) As Byte
'Use For Next to convert and store chrData into bytDataToHash.
For i As Integer = 0 To chrData.GetUpperBound(0)
bytDataToHash(i) = CByte(Asc(chrData(i)))
Next
'Declare what hash to use.
Dim SHA512 As New System.Security.Cryptography.SHA512Managed
'Declare bytResult, Hash bytDataToHash and store it in bytResult.
Dim bytResult As Byte() = SHA512.ComputeHash(bytDataToHash)
'Declare bytIV(15). It will hold 128 bits.
Dim bytIV(15) As Byte
'Use For Next to put a specific size (128 bits) of bytResult into bytIV.
'The 0 To 30 for bytKey used the first 256 bits of the hashed password.
'The 32 To 47 will put the next 128 bits into bytIV.
For i As Integer = 32 To 47
bytIV(i - 32) = bytResult(i)
Next
Return bytIV 'Return the IV.
End Function
'****************************


'** Encrypt/Decrypt File
'****************************
Public Enum CryptoAction
'Define the enumeration for CryptoAction.
ActionEncrypt = 1
ActionDecrypt = 2
End Enum
Public Sub EncryptOrDecryptFile(ByVal strInputFile As String, _
ByVal strOutputFile As String, _
ByVal bytKey() As Byte, _
ByVal bytIV() As Byte, _
ByVal Direction As CryptoAction)
Try 'In case of errors.
'Setup file streams to handle input and output.
fsInput = New System.IO.FileStream(strInputFile, IO.FileMode.Open, IO.FileAccess.Read)
fsOutput = New System.IO.FileStream(strOutputFile, IO.FileMode.OpenOrCreate, IO.FileAccess.Write)
fsOutput.SetLength(0) 'make sure fsOutput is empty
'Declare variables for encrypt/decrypt process.
Dim bytBuffer(4096) As Byte 'holds a block of bytes for processing
Dim lngBytesProcessed As Long = 0 'running count of bytes processed
Dim lngFileLength As Long = fsInput.Length 'the input file's length
Dim intBytesInCurrentBlock As Integer 'current bytes being processed
Dim csCryptoStream As CryptoStream
'Declare your CryptoServiceProvider.
Dim cspRijndael As New System.Security.Cryptography.RijndaelManaged
'Setup Progress Bar
' pbStatus.Text = 0
' pbStatus.Maximum = 100
'Determine if ecryption or decryption and setup CryptoStream.
Select Case Direction
Case CryptoAction.ActionEncrypt
csCryptoStream = New CryptoStream(fsOutput, _
cspRijndael.CreateEncryptor(bytKey, bytIV), _
CryptoStreamMode.Write)
Case CryptoAction.ActionDecrypt
csCryptoStream = New CryptoStream(fsOutput, _
cspRijndael.CreateDecryptor(bytKey, bytIV), _
CryptoStreamMode.Write)
End Select
'Use While to loop until all of the file is processed.
While lngBytesProcessed < lngFileLength
'Read file with the input filestream.
intBytesInCurrentBlock = fsInput.Read(bytBuffer, 0, 4096)
'Write output file with the cryptostream.
csCryptoStream.Write(bytBuffer, 0, intBytesInCurrentBlock)
'Update lngBytesProcessed
lngBytesProcessed = lngBytesProcessed + _
CLng(intBytesInCurrentBlock)
'Update Progress Bar
' pbStatus.Value = CInt((lngBytesProcessed / lngFileLength) * 100)
End While
'Close FileStreams and CryptoStream.
csCryptoStream.Close()
fsInput.Close()
fsOutput.Close()
Catch e As Exception
MsgBox(e.Message, MsgBoxStyle.Exclamation)
End Try
End Sub

/////Calling function to Encrypt file.

'Encrypted The XML
Dim bytKey As Byte()
Dim bytIV As Byte()
'Send the password to the CreateKey function.
bytKey = CreateKey("soumitra")
'Send the password to the CreateIV function.
bytIV = CreateIV("soumitra")
'Start the encryption.
EncryptOrDecryptFile(Application.StartupPath & "\config.xml", "C:\Foldername\" & txtAgencyId.Text.Trim() & "\config.xml.encrypted", _
bytKey, bytIV, CryptoAction.ActionEncrypt)


/////Calling function to DEcrypt file.
Dim bytKey As Byte()
Dim bytIV As Byte()
'Send the password to the CreateKey function.
bytKey = CreateKey("soumitra")
'Send the password to the CreateIV function.
bytIV = CreateIV("soumitra")
'Start the encryption.
'Application.StartupPath & "\config.xml.encrypted"
EncryptOrDecryptFile(strDecryptPath & "\config.xml.encrypted", Application.StartupPath & "\config.xml", _
bytKey, bytIV, CryptoAction.ActionDecrypt)