>>But it's not clear where and how you are seeing this message? IAC, it would seem that this particular .FromBase64String() is not causing the problem.
>>FWIW there are two exception messages for .FromBase64String() - the one you see and "Invalid character in a Base-64 string". The latter takes precedence so you can be confident that there are no invalid characters in the string.
>>See help for valid length - basically the number of non-whitespace characters must be zero or a multiple of four.
>>If you are creating initVector somewhere how are you doing it?
>
>Here is the Decrypt() method:
>
>

>        Public Function Decrypt(ByVal data As String, ByVal userKey As String, _
>         ByVal alg As EncryptionAlgorithm) As Boolean
>            Dim tok As [String]() = data.Split(New Char() {" "c})
>            Dim initVector As [String] = tok(0)
>
>            data = tok(1)
>
>            ' Set up the Decryptor object
>            Dim dec As New Decryptor(alg)
>
>            ' Set the Initialization Vector
>            dec.IV = Convert.FromBase64String(initVector)
>
>            Dim key As Byte() = Encoding.Default.GetBytes(userKey)
>
>            ' Perform the decryption
>            If Not dec.Decrypt(Convert.FromBase64String(data), key) Then
>               Return False
>            End If
>
>            cDecrypt = Encoding.Default.GetString(dec.oByte)
>            Return True
>        End Function
>

>
>I adjusted it to remove the Try Catch so it would be easier to follow it.

Like Bonnie I'm now confused. The above doesn't tell me anything about the content of InitVector. But I think we're all agreed that the dec.IV assign line (which you originally had in the try block?) could not have been the cause of the message you were seeing. But you didn't explain where this message was originating from. IAC could the error have been in the second use of Convert.FromBase64String ?
Regards,
Viv