-
Here is a basic version of an encryption sscheme i devloped.
If you have the time and the knowledge please test it.
[list=A][*]Is it a strong encryption?[*]Did you brake it? How?[*]Any ideas for improvement?[/list=A]
Code:
Global dKey as Double,sKey as Double,D(255) As Byte
Function Encrypt(OriginalFile)
'Promt user to enter a Key: call Key(text1.text)
sfile=OriginalFile
Rnd (-dKey): Randomize dKey
xfile = sfile & ".stdenc"
Open sfile For Random As #1 Len = 1
lenfile = LOF(1)
Close
ReDim C(lenfile) As Byte, x(lenfile) As Byte
Open sfile For Binary As #1
Get #1, 1, C()
Close
y = 0
For i = 1 To lenfile
y = y + 1
y = y Mod 255 + 1
x(i) = C(i) Xor D(y)
Next i
Open xfile For Binary As #1
Put #1, 1, x()
Close
End Function
Private Sub Key (x as String)
For i = 1 To (Len(x) - 1)
t = t + Asc(Mid(x, i, 1))
Next i
t = t - Asc(Mid(x, Len(x), 1))
t = t ^ 2 - t
Rnd (-t)
Randomize t
sKey = Int(Rnd * 2123234345) + 2000398
dKey = Int(sKey / 1000 + 603)
Rnd (-sKey)
Randomize sKey
For i = 1 To 255
g = Int(Rnd * 255) + 1
h = Int(Rnd * 255) + 1
D(i) = g Xor h
Next i
End Sub
Let me know what you think
-
Explaination
A breif explaination:
First, the key is not stored in the encrypted file. A numder, i.e. TestNum, is created in the Key( ) sub, and stored in the encrypted file.
The Key verification uses the User inputed key and the Key( ) sub to create a TestNum. If the TestNum created by Key( ) is the same as
the TestNum in the encrypted file, then the encrypted file is decrypted.
Second, the plainFile(unencrypted file) is loaded into an array.
Code:
Open sfile For Random As #1 Len = 1
lenfile = LOF(1)
Close
ReDim C(lenfile) As Byte, x(lenfile) As Byte 'Create the array
Open sfile For Binary As #1
Get #1, 1, C() 'load whole file into array
Close
The array C( ) is then encrypted.
Code:
For i = 1 To lenfile
y = y + 1
y = y Mod 255 + 1
x(i) = C(i) Xor D(y)
Next i
This method is faster than reading one byte, encrypting it, and then writing it.
