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Public Class frmCrypto
'Creates the Byte-Key which will be used in subEncryptOrDecryptFile
'The first 32 bytes of the Password-Hash will be used as the Key
'
'Input:
' strPassword The Passsword to encrypt
'Output:
' funCreateKey The Key to use in subEncryptOrDecryptFile
'
Private Function funCreateKey(ByVal strPassword As String) As Byte()
Try
'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.
Catch ex As Exception
'ERROR
End Try
End Function
'Creates the Byte-Initialization Vector which will be used in subEncryptOrDecryptFile
'The first Bytes 32 to 47 of the Password-Hash will be used as the IV
'
'Input:
' strPassword The Passsword to encrypt
'Output:
' funCreateIV The IV to use in subEncryptOrDecryptFile
'
Private Function funCreateIV(ByVal strPassword As String) As Byte()
Try
'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.
Catch ex As Exception
'ERROR
End Try
End Function Private Enum CryptoAction
'Define the enumeration for CryptoAction.
ActionEncrypt = 1
ActionDecrypt = 2
End Enum 'It will encrypt or decrypt a file
'
'Input:
' strInputFile The File to encrypt/decrypt
' strOutputFile The encrypted/decrypted output-file
' bytKey() The Key from funCreateKey
' bytIV() The IV from funCreateIV
' Direction Encrypt or decrypt
'
Private Sub subEncryptOrDecryptFile(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.
Dim fsInput As System.IO.FileStream
Dim fsOutput As System.IO.FileStream 'Setup file streams to handle input and output.
fsInput = New System.IO.FileStream(strInputFile, FileMode.Open, _
FileAccess.Read)
fsOutput = New System.IO.FileStream(strOutputFile, _
FileMode.OpenOrCreate, _
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 '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
pbStatusFile.Value = CInt((lngBytesProcessed / lngFileLength) * 100) + 200
Application.DoEvents()
End While 'Close FileStreams and CryptoStream.
csCryptoStream.Close()
fsInput.Close()
fsOutput.Close()
Catch ex As Exception
If ex.Message = "Zeichenabstände sind ungültig und können nicht entfernt werden." Then
MsgBox("ACHTUNG: Das Passwort ist falsch! Die Datei kann nicht entschlüsselt werden.")
Exit Sub
End If
'ERROR
End Try
End Sub 'Calculates teh Hash of a file
'
'Input:
' strFile The file to hash
'Output:
' funSHA1HashFile The generated hash of the file
'
Public Function funSHA1HashFile(ByVal strFile As String) As String
Dim SHA1 As New SHA1CryptoServiceProvider
Dim Hash As Byte()
Dim Result As String = ""
Dim Tmp As String = "" Try
Dim FN As New FileStream(strFile, FileMode.Open, FileAccess.Read, FileShare.Read, 8192)
SHA1.ComputeHash(FN)
FN.Close() Hash = SHA1.Hash
For i As Integer = 0 To Hash.Length - 1
Tmp = Hex(Hash(i))
If Len(Tmp) = 1 Then Tmp = "0" & Tmp
Result += Tmp
Next
Return Result
Catch ex As Exception
'ERROR
End Try
End Function
End Class |
