Encryption / string encoding
From: Sparky (mark.smith_at_nospam.farmade.com)
Date: 05/22/03
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Date: Thu, 22 May 2003 16:37:17 +0100
Hi
I'm using Visual Studio Magazines Crypto class, as described in Jan 2003.
The problem that I'm having is that I am encrypting a string, and then at a
later date decrypting the string. If I debug.print the decrypted string, it
is correct but has no end quote displayed.
ie. in the output window, rather than "hello" being displayed, "hello is
displayed. It looks like the string is now longer than it ought to be but
has funny characters appended to the end. This affects webservices,. ie. I
can't pass the string, and also affects sql as I can't use that string in an
sql statement. I have tried Trim'ming etc but to no avail. All I want is my
original string back....
I've pasted below the encryption / decrption code. I think it's just a case
of doing something like Convert.ToString (although that doesn't work but I
suspect something similar will!)
Any help much appreciated!
Mark
==========================
Public Function DecryptString(ByVal EncryptedString As String) As String
If mbKeyIsSet Then
Return _DecryptString(EncryptedString, True)
Else
Throw New Exception(mksKeyNotSetException)
End If
End Function
Private Function _DecryptString(ByVal EncryptedString As String, ByVal
Base64 As Boolean) As String
Try
'put string in byte array depending on Base64 flag
Dim byteArray() As Byte
If Base64 Then
byteArray = Convert.FromBase64String(EncryptedString)
Else
byteArray = BytesFromString(EncryptedString)
End If
'create the streams, decrypt and return a string
Dim msEnc As New MemoryStream(byteArray)
Dim msPlain As MemoryStream = DecryptStream(msEnc)
Return BytesToString(msPlain.GetBuffer)
Catch ex As Exception
'Debug.WriteLine("_DecryptString Error: " & ex.ToString)
'Return String.Empty
cFmsException.ThrowFMS(Me.GetType.FullName, ex)
End Try
End Function
Private Function BytesToString(ByVal byteArray() As Byte) As String
Return (New UnicodeEncoding).GetString(byteArray)
'Return (New ASCIIEncoding).GetString(byteArray)
End Function
'encrypt a string - wrapper without Base64 flag (True by default)
Public Function EncryptString(ByVal PlainText As String) As String
If mbKeyIsSet Then
Return _EncryptString(PlainText, True)
Else
Throw New Exception(mksKeyNotSetException)
End If
End Function
Private Function _EncryptString(ByVal PlainText As String, ByVal Base64 As
Boolean) As String
Try
'put string in byte array
Dim byteArray() As Byte = BytesFromString(PlainText)
'create streams and encrypt
Dim msPlain As New MemoryStream(byteArray)
Dim msEnc As MemoryStream = EncryptStream(msPlain)
'return string depending on Base64 flag
If Base64 Then
Return Convert.ToBase64String(msEnc.ToArray)
Else
Return BytesToString(msEnc.ToArray)
End If
Catch ex As Exception
'Debug.WriteLine("_EncryptString Error: " & ex.ToString)
'Return String.Empty
cFmsException.ThrowFMS(Me.GetType.FullName, ex)
End Try
End Function
Public Function EncryptStream(ByVal PlainStream As MemoryStream) As
MemoryStream
If mbKeyIsSet Then
Try
'open stream for encrypted data
Dim encStream As New MemoryStream
'create Crypto Service Provider, set key, transform and crypto stream
Dim oCSP As New RijndaelManaged
oCSP.Key = mbytKey
oCSP.IV = mbytIV
Dim ct As ICryptoTransform = oCSP.CreateEncryptor()
Dim cs As CryptoStream = New CryptoStream(encStream, ct,
CryptoStreamMode.Write)
'get input stream into byte array
Dim byteArray() As Byte = PlainStream.ToArray()
'write input bytes to crypto stream and close up
cs.Write(byteArray, 0, CType(PlainStream.Length, Integer))
cs.FlushFinalBlock()
cs.Close()
Return encStream
Catch ex As Exception
'Debug.WriteLine("EncryptStream Error: " & ex.ToString)
'Return Stream.Null
cFmsException.ThrowFMS(Me.GetType.FullName, ex)
End Try
Else
Throw New Exception(mksKeyNotSetException)
End If
End Function
Public Function DecryptStream(ByVal EncryptedStream As MemoryStream) As
MemoryStream
If mbKeyIsSet Then
Try
'create Crypto Service Provider, set key, transform and crypto stream
Dim oCSP As New RijndaelManaged
oCSP.Key = mbytKey
oCSP.IV = mbytIV
Dim ct As ICryptoTransform = oCSP.CreateDecryptor()
Dim cs As CryptoStream = New CryptoStream(EncryptedStream, ct,
CryptoStreamMode.Read)
'get bytes from encrypted stream
Dim byteArray(CType(EncryptedStream.Length - 1, Integer)) As Byte
Dim iBytesIn As Integer = cs.Read(byteArray, 0,
CType(EncryptedStream.Length, Integer))
cs.Close()
'create and write the decrypted output stream
Dim plainStream As New MemoryStream
plainStream.Write(byteArray, 0, iBytesIn)
Return plainStream
Catch ex As Exception
'Debug.WriteLine("DecryptStream Error: " & ex.ToString)
'Return Stream.Null
cFmsException.ThrowFMS(Me.GetType.FullName, ex)
End Try
Else
Throw New Exception(mksKeyNotSetException)
End If
End Function
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