You should use Encoding.Default to get properly localized data. ASCII should be used only if you're dealing with true ASCII (lower 128 or 255 with default ASCII encoding) which is rarely the case. If you need to two way convert always use the Default Encoding which will use your machine's configured codepage to convert to and from Unicode.

+++ Rick ---

>I am using a standard .NET code to encrypt some strings. This is widely used across the net. The code supports DES, RC2, Rinjdael and TripleDes. The entry code to encrypt is as follow, with minor modifications to fit our personal needs:
>
>

>        Public Function Encrypt(ByVal data As String, ByVal userKey As String, _
>         ByVal alg As EncryptionAlgorithm) As Boolean
>            Dim cipherText As Byte()
>
>            ' Create the encryptor object, specifying 3DES as the encryption algorithm
>            Dim enc As New Encryptor(alg)
>
>            ' Get the connection string as a byte array
>            Dim plainText As Byte() = Encoding.ASCII.GetBytes(data)
>            Dim key As Byte() = Encoding.ASCII.GetBytes(userKey)
>
>            ' Perform the encryption
>            If Not enc.Encrypt(plainText, key) Then
>
>                ' Get the proper definition as per the current scope
>                If oProcess Is Nothing Then
>                    oApp.ErrorSetupControlledByTheFramework("Unable to encrypt. " + _
>                     "The message is: " + enc.cError)
>                Else
>                    oProcess.ErrorSetupControlledByTheFramework("Unable to encrypt. " + _
>                     "The message is: " + enc.cError)
>                End If
>
>                Return False
>            End If
>
>            cipherText = enc.oMemoryStreamEncryptedData
>
>            ' Store the intialization vector, as this will be required for decryption
>            Dim initVector As [String] = Convert.ToBase64String(enc.IV)
>
>            cEncrypt = initVector + " " + Convert.ToBase64String(cipherText)
>            Return True
>        End Function
>

>
>The problem I have is I just discovered that if I want to encrypt a string containing a French character that I will loose that on the decryption. Anyone would know what I would have to do, if anything could be done, to support those characters at the encryption and decryption level?