please explain this fun code.(Cryptography.EncryptDecrypt)

Question

Public Function calculateCustomerChecksum(ByVal xlWorkSheet As Microsoft.Office.Interop.Excel.Worksheet, ByVal rownumber As Integer) As Boolean

Try

Dim i As Integer = 0, checksum1 As Double, strchecksum1 As String, checksum2 As Double, strchecksum2 As String

Dim signchecksum1 As Double = 0, signchecksum2 As Double = 0

For i = 2 To rownumber - 1

checksum1 += System.Convert.ToDouble(Trim(CheckForZero(xlWorkSheet.Cells(i, 9).Value)))

checksum2 += System.Convert.ToDouble(Trim(CheckForZero(xlWorkSheet.Cells(i, 10).Value)))

Application.DoEvents()

Next

signchecksum1 = checksum1

signchecksum2 = checksum2

'If checksum1 < 0 Then

' checksum1 = -checksum1

'End If

'If checksum2 < 0 Then

' checksum2 = -checksum2

'End If

'strchecksum1 = ((System.Math.Floor(checksum1) * 4123) + 675).ToString & GetDecimalpointValue(checksum1)

'strchecksum1 = calculatelength(strchecksum1) & strchecksum1

'strchecksum1 = strchecksum1 & Addallnumbers(strchecksum1) & "A"

'strchecksum2 = ((System.Math.Floor(checksum2) * 4123) + 675).ToString & GetDecimalpointValue(checksum2)

'strchecksum2 = calculatelength(strchecksum2) & strchecksum2

'strchecksum2 = strchecksum2 & Addallnumbers(strchecksum2) & "A"

'If signchecksum1 < 0 Then

' strchecksum1 = -strchecksum1

'End If

'If signchecksum2 < 0 Then

' strchecksum2 = -strchecksum2

'End If

Dim m_encrypt As New Cryptography.EncryptDecrypt

strchecksum1 = m_encrypt.encrypt(checksum1) & "A"

strchecksum2 = m_encrypt.encrypt(checksum2) & "A"

If Trim(strchecksum1) = Trim((xlWorkSheet.Cells(xlWorkSheet.UsedRange.Rows.Count, 9).Value)) Then

If Trim(strchecksum2) = Trim((xlWorkSheet.Cells(xlWorkSheet.UsedRange.Rows.Count, 10).Value)) Then

' strchecksum2 = ((System.Math.Floor(System.Convert.ToDouble(Trim(CheckForZero(xlWorkSheet.Cells(xlWorkSheet.UsedRange.Rows.Count - 1, 1).Value)))) * 4123) + 675).ToString & GetDecimalpointValue(System.Convert.ToDouble(Trim(CheckForZero(xlWorkSheet.Cells(xlWorkSheet.UsedRange.Rows.Count - 1, 1).Value))))

'strchecksum2 = calculatelength(strchecksum2) & strchecksum2

'strchecksum2 = strchecksum2 & Addallnumbers(strchecksum2) & "A"

strchecksum2 = m_encrypt.encrypt(xlWorkSheet.Cells(xlWorkSheet.UsedRange.Rows.Count - 1, 1).Value) & "A"

If Trim(strchecksum2) = Trim((xlWorkSheet.Cells(xlWorkSheet.UsedRange.Rows.Count, 3).Value)) Then

Return True

Else

Return False

End If

Else

Return False

End If

Else

Return False

End If

Catch ex As Exception

Return False

End Try

Return False

'checksum = calculatelength() & ((System.Math.Floor(checksum) * 4193) + 675).ToString

End Function