encryption

[alkatran]

Hi, I,ve been wroking on an algorythm to encrypt data I save to
files... so far I,ve got it mixing and raising it.. I just wanted to
know how I could put... uh.. 'junk' characters in it. I,ve tried it but
nothing's worked so far. Here's what I've got so far...

---------------------------------------
Private Sub demix(code As Variant)
Dim code2 As String
code = CStr(code)
b = 1
Do Until a = Len(code) + 3
For a = 1 To Len(code) Step 2
If Asc(Mid(code, a, 1)) = b Then code2 = code2 + Mid(code, a + 1, 1): b = b + 1: c = True
If (b - 1) * 2 >= Len(code) Then GoTo 1
Next a
If c = False Then MsgBox "Decryption error", vbCritical, "Warning": Call raise(code): Exit Sub
c = False
Loop
1
code = code2
Text1.Text = code
End Sub

Private Sub mix(code As Variant)
Dim codeset() As Boolean
Dim code2 As String
Dim counter As Variant
code = CStr(code)
ReDim codeset(Len(code))
Do Until a = Len(code) + 1
a = Int(Rnd * Len(code)) + 1
If codeset(a) = False Then codeset(a) = True: code2 = code2 + Chr$(a): code2 = code2 + Mid(code, a, 1): counter = counter + 1
If counter = Len(code) Then a = Len(code) + 1
Loop
code = code2
Text1.Text = code
End Sub

Private Sub raise(code As Variant)
Dim code2 As String
code = CStr(code)
On Error GoTo 1
For a = 1 To Len(code)
code2 = code2 + Chr$(Asc(Mid(code, a, 1)) + 3)
Next a
code = code2
Text1.Text = code
Exit Sub
1
MsgBox "Encryption error", vbCritical, "Warning"
End Sub

Private Sub lower(code As Variant)
Dim code2 As String
code = CStr(code)
On Error GoTo 1
For a = 1 To Len(code)
code2 = code2 + Chr$(Asc(Mid(code, a, 1)) - 3)
Next a
code = code2
Text1.Text = code
Exit Sub
1
MsgBox "Decryption error", vbCritical, "Warning"
End Sub

Private Sub Command1_Click()
If Not Text1.Text = "" And Not Len(Text1.Text) > 255 Then
Call mix(Text1.Text)
Call raise(Text1.Text)
End If
End Sub
Private Sub Command2_Click()
If Not Text1.Text = "" And Not Len(Text1.Text) > 255 * 2 Then
Call lower(Text1.Text)
Call demix(Text1.Text)
End If
End Sub
-------------------------------------------

Here's "hello" after I've encrypted it 5 times:

&$ RD;~%> ,O
{7

P/+
Q

"#,+-0L8"' @<'&B*!9J CwGK!A4(H$2.NI%?)36#1.F
5{tS)E(-=:*M

any ideas?

[Zaei]

Using the Rnd() function in encryption is a big no-no. You have no idea what is going to come out of that function, which means that if you use it to encrypt (as you are), you have no way to decrypt. I would suggest that at every N characters in the source string, you insert M junk characters:

For i = 1 to Len(src)
  dest = dest & Mid(src, i, 1)
  If i mod N = 0 Then
    For j = 0 to M - 1
       dest = dest & chr(Int(Rnd() * 255))
    Next j
   End If
Next i

Z.

[alkatran]

the rnd function makes the encryption better, if u'd looked more closely at the code, you'd have noticed that it puts what came out of the rnd function in the string, then the decrypt uses that to put it back together....