by Richard j Chute (1 Submission)
Category: String Manipulation
Compatability: Visual Basic 3.0
Difficulty: Unknown Difficulty
Originally Published: Tue 4th April 2000
Date Added: Mon 8th February 2021
Rating: 
(1 Votes)
This code uses two forms of encryption, and a simple form of compression to thoroughly encrypt any string given (the compression doesn't work
VBcoders
Text1.text = encrypt$(compress$(Text1.text))
end sub
private sub Command2_click()
Text1.text = decompress$(decrypt$(Text1.text))
end sub
Public Function compress$(inString$)
r$ = ""
For i = 1 To Len(inString$)
a$ = Mid$(inString$, i, 1)
If a$ = " " Then
i = i + 1
a$ = Mid$(inString$, i, 1)
a$ = Chr$(127 + Asc(a$))
End If
r$ = r$ + a$
Next i
compress$ = r$
End Function
Public Function decompress$(inString$)
r$ = ""
For i = 1 To Len(inString$)
a$ = Mid$(inString$, i, 1)
If Asc(a$) >= 127 Then a$ = " " + Chr$(Asc(a$) - 127)
r$ = r$ + a$
Next i
decompress$ = r$
End Function
Public Function decryptIt$(inString$)
Dim lineLen%(10)
Dim lineString$(10)
onLine% = 1
l% = 14
head$ = Left$(inString$, l% + 1)
cI% = Asc(Left$(inString$, 1))
For i = 1 To 10
lineLen%(i) = Asc(Mid$(inString$, i + 1, 1))
Next i
tL% = 0 'Asc(Mid$(inString$, 12, 1))
For i = 1 To 10
tL% = tL% + lineLen%(i)
Next i
For i = 1 To 10
lineString$(i) = inverseLine$(Mid$(inString$, l%, lineLen%(i)))
l% = l% + lineLen%(i)
Next i
c% = 1: l% = 1
un$ = ""
For i = 1 To tL%
a% = Asc(Mid$(lineString$(l%), c%, 1)) - cI%
If a% < 0 Then a% = a% + 255
un$ = un$ + Chr$(a%)
l% = l% + 1
If l% = 11 Then l% = 1: c% = c% + 1
Next i
decryptIt$ = un$
End Function
Public Function encryptIt$(inString$, comTyp%)
'comTyp% = 0 for not compressed, 1 for compressed
Dim lineString$(10)
onLine% = 1
startStr$ = inString$
For i = 1 To Len(startStr$)
a = Asc(Mid$(startStr$, i, 1)) + codeIncrease%
If a > 255 Then a = a - 255
lineString$(onLine%) = lineString$(onLine%) + Chr$(a)
onLine% = onLine% + 1
If onLine% = 11 Then onLine% = 1
Next i
head$ = ""
For i = 1 To 10
head$ = head$ + Chr$(Len(lineString$(i)))
Next i
outString$ = Chr$(codeIncrease%) + head$ + Chr$(Len(" ")) + Chr$(comTyp% + 254)
For i = 1 To 10
outString$ = outString$ + inverseLine$(lineString$(i))
Next i
encryptIt$ = outString$
End Function
Private Function inverseLine$(inString$)
a$ = ""
For i = Len(inString$) To 1 Step -1
a$ = a$ + Mid$(inString$, i, 1)
Next i
inverseLine$ = a$
End Function
Public Function determineType(inString$)
'0 = regular text file
'1 = is compressed
'2 = is encrypted
'3 = is both
determineType = 0
a$ = Mid$(inString$, 12, 1)
If a$ = Chr$(255) Then
determineType = 3
ElseIf a$ = Chr$(254) Then
determineType = 2
Else
For i = 1 To Len(inString$)
If Mid$(inString$, i, 1) = " " Then Exit For
Next i
If i = Len(inString$) Then determineType = 1
End If
End Function
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