Yubico Forum

    Private Sub btDecrypt_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btDecrypt.Click
        Dim crypto As New System.Security.Cryptography.RijndaelManaged
        Dim encryptedData As Byte() = FromHex("f9ef77d27b8fed0f088963be7d3e2f15")
        crypto.Key = FromHex("265670755823513b6d54423c79536560")
        crypto.IV = New Byte(encryptedData.Length - 1) {}

        Dim encryptedMemStream As New System.IO.MemoryStream(encryptedData, 0, encryptedData.Length)
        Dim b() As Byte = New Byte(encryptedData.Length - 1) {}

        Dim cs As New System.Security.Cryptography.CryptoStream(encryptedMemStream, crypto.CreateDecryptor(), System.Security.Cryptography.CryptoStreamMode.Read)

        Try
            cs.Read(b, 0, encryptedData.Length - 1)
        Catch ex As System.Security.Cryptography.CryptographicException
            Throw New System.Security.Cryptography.CryptographicException("Unable to decrypt data. The provided key may be invalid.", ex)
        Finally
            cs.Close()
        End Try
        tbEncryptResult.Text = ToHex(b)
    End Sub

    Shared Function ToHex(ByVal ba() As Byte) As String
        If ba Is Nothing OrElse ba.Length = 0 Then
            Return ""
        End If
        Const HexFormat As String = "{0:X2}"
        Dim sb As New System.Text.StringBuilder
        For Each b As Byte In ba
            sb.Append(String.Format(HexFormat, b))
        Next
        Return sb.ToString
    End Function

    Shared Function FromHex(ByVal hexEncoded As String) As Byte()
        If hexEncoded Is Nothing OrElse hexEncoded.Length = 0 Then
            Return Nothing
        End If
        Try
            Dim l As Integer = Convert.ToInt32(hexEncoded.Length / 2)
            Dim b(l - 1) As Byte
            For i As Integer = 0 To l - 1
                b(i) = Convert.ToByte(hexEncoded.Substring(i * 2, 2), 16)
            Next
            Return b
        Catch ex As Exception
            Throw New System.FormatException("The provided string does not appear to be Hex encoded:" & _
                Environment.NewLine & hexEncoded & Environment.NewLine, ex)
        End Try
    End Function

        crypto.Padding = System.Security.Cryptography.PaddingMode.None