This is an improvement to the tip "
Encrypt a String Easily." I found that the
szEncryptDecrypt function in this tip did not handle unicode strings properly, but otherwise worked well. The changes in the following version should work for any string by explicitly converting each character to ASCII and back. As with the other function, this is not strong encryption, but it is fast and will dissuade 99 percent of people.
'simple encryption function obtained from www.devx.com
'written by Rob Bovey
'updated by Scott Likely
Function szEncryptDecrypt(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
szEncryptDecrypt = strOutput
End Function
