Solution – Challenge 40 – Cryptography Challenge 2 – Fully Functional Caesar’s Shift Cipher

Below is a possible solution to the challenge – Challenge 40 – Cryptography Challenge 2 – Fully Functional Caesar’s Shift Cipher

1. Make a backup of your workbook
2. Open your workbook and ALT+F11
3. Locate your Workbook name in Project Explorer Window
4. Right click on your workbook name > Insert > Module
5. Copy paste the Macro code given below
6. Save your file as .xlsm
7. Call your function as =EncryptCS(A1,$B$2)

Function EncryptCS(PText, Shift) As String
    Dim Ws As Worksheet
    Dim i As Long
    Dim CText As String
    Dim PArr, CArr
    Application.Volatile
    PArr = Split(StrConv(PText, vbUnicode), vbNullChar)
    ReDim CArr(UBound(PArr) - 1)
    For i = LBound(PArr) To UBound(PArr) - 1
        If Abs(77.5 - Asc(UCase(PArr(i)))) < 13 Then
            If Asc(LCase(PArr(i))) + Shift > 122 Then
                CArr(i) = Chr(Asc(PArr(i)) + Shift - 26)
                Else
                CArr(i) = Chr(Asc(PArr(i)) + Shift)
            End If
        Else
            CArr(i) = PArr(i)
        End If
    Next i
    EncryptCS = Join(CArr, "")
End Function

A workbook containing the above solution can be downloaded from Solution – Challenge 40 – Cryptography Challenge 2 – Fully Functional Caesar’s Shift Cipher.