by John Cui (1 Submission)
Category: Encryption
Compatability: Visual Basic 3.0
Difficulty: Unknown Difficulty
Date Added: Wed 3rd February 2021
Rating: 
(5 Votes)
A StreamCipher encryption similar to the first 'Cipher' but now it can encrypt any text or binary file.
Inputs
PlainText(the text to be encrypted/decrypted), Secret(the password)
Assumes
There is only one function to Encrypt/Decrypt the strings. It is to this point stable that you can encrypt the same string multiple times using different passwords every time and then decrypt in the reverse order.
Code Returns
Encrypted/Decrypted string
Side Effects
I tested the code in VB6.0 but I mainly used code that's been part of VB for a while so it should work with ver. 3 and up. One side effect is the cipher speed. It's still a little slow but I'm working on an 8, 16, and 32 cipher code which would hopefully be fast. Warning!! Keep the strings your working with in memory rather than in an object such as a textbox because there would be loss of data when a string with ascii < 32 is used in a textbox.
API Declarations
VBcodersPublic Function Cipher(PlainText, Secret)
Dim a, b, c
Dim pTb, cTb, cT
For i = 1 To Len(PlainText)
pseudoi = i Mod Len(Secret)
If pseudoi = 0 Then pseudoi = 1
a = Mid(Secret, pseudoi, 1)
b = Mid(Secret, pseudoi + 1, 1)
c = Asc(a) Xor Asc(b)
pTb = Mid(PlainText, i, 1)
cTb = c Xor Asc(pTb)
cT = cT + Chr(cTb)
Form1.Label1.Caption = i
DoEvents
Next i
EnCipher = cT
End Function
