Encrypt Decrypt in VB6

Following function performs encryption as well as decryption

Example – Uses Base64 functions from previous post

Encryption & decryption with base64 output

sCmd=”this is test”

queryString = (Base64Encoding(EncryptDecrypt(sCmd), "myWord", "13"))

queryString = (EncryptDecrypt(Base64Decoding(sCmd), "myWord", "13"))

Public Function EncryptDecrypt(ByVal szData As String, ByVal salt As String, ByVal pepper As String) As String
    ''' salt is a key value can be changed to alter the
    ''' encryption, but it must be the same for both
    ''' encryption and decryption.
    ''' pepper is optional, and may be any
    ''' value 0-64.
    ''' Likewise, it needs to be the same coming/going.

    Dim bytKey() As Byte
    Dim bytData() As Byte
    Dim lNum As Long
    Dim szKey As String
    Dim strOutput As String

    'use a default key if none given
    If Len(salt) = 0 Then salt = "123456"
    
    'make sure the key is as long as the text we want to encode
    For lNum = 1 To ((Len(szData) / Len(salt)) + 1)
        szKey = szKey & salt
    Next lNum
    
    ReDim bytKey(Len(szData)) As Byte
    ReDim bytData(Len(szData)) As Byte
    
    'copy the key into the key byte array
    'must do it this way to avoid unicode problems
    'make it no longer than the text we want to encode
    For lNum = 1 To Len(szData)
        bytKey(lNum) = Asc(Mid$(szKey, lNum, 1))
    Next lNum
    
    'copy the text we want to encode into the data byte array
    'must do it this way to avoid unicode problems
    For lNum = 1 To Len(szData)
        bytData(lNum) = Asc(Mid$(szData, lNum, 1))
    Next lNum
    
    strOutput = ""

    For lNum = 1 To UBound(bytData)
        If lNum Mod 2 Then
            bytData(lNum) = bytData(lNum) Xor (bytKey(lNum) + pepper)
            strOutput = strOutput & Chr(bytData(lNum))
        Else
            bytData(lNum) = bytData(lNum) Xor (bytKey(lNum) - pepper)
            strOutput = strOutput & Chr(bytData(lNum))
        End If
    Next lNum

    EncryptDecrypt = strOutput
End Function