B4A Class ROT13 and Atbash substitution cipher Code

'Code module
'Subs in this code module will be accessible from all modules.
Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'These variables can be accessed from all modules.

End Sub
'"rotate by 13 places" substitution cipher
'http://en.wikipedia.org/wiki/ROT13
Public Sub ROT13(stringx As String) As String
    Dim ByteX () As Byte
    ByteX=stringx.GetBytes("UTF8")
    Dim finalX As String
    For x=0 To ByteX.Length-1
        If (ByteX(x)>=97 AND ByteX(x)<=109 )OR (ByteX(x)>=65 AND ByteX(x)<=77 ) Then
            ByteX(x)=ByteX(x)+13
        Else If (ByteX(x)>=110 AND ByteX(x)<=122 )OR (ByteX(x)>=78 AND ByteX(x)<=90 )  Then
            ByteX(x)=ByteX(x)-13
        End If
        finalX=finalX & Chr(ByteX(x))
    Next
    Return finalX
End Sub
'"Atbash" substitution cipher
'http://en.wikipedia.org/wiki/Atbash
Sub Atbash(StringX As String) As String
    Dim ByteX () As Byte
    ByteX=StringX.GetBytes("UTF8")
    Dim finalX As String
    '65-90   97- 122
    For x=0 To ByteX.Length-1
        If (ByteX(x)>=65 AND ByteX(x)<=90 ) Then
            ByteX(x)=Abs(ByteX(x)-155)                    '155 comes from 65+90
        Else If (ByteX(x)>=97 AND ByteX(x)<=122 ) Then
            ByteX(x)=Abs(ByteX(x)-219)                    '219 comes from 97+122
        End If
        finalX=finalX & Chr(ByteX(x))
    Next
    Return finalX
End Sub