#Region "Encryption decryption"
Dim sbox(255)
Dim key(255)
Sub RC4Initialize(ByVal strPwd As String)
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
'::: This routine called by EnDeCrypt function. Initializes the :::
'::: sbox and the key array) :::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Dim tempSwap
Dim a
Dim b, intLength
intLength = Len(strPwd)
For a = 0 To 255
key(a) = Asc(Mid(strPwd, (a Mod intLength) + 1, 1))
sbox(a) = a
Next
b = 0
For a = 0 To 255
b = (b + sbox(a) + key(a)) Mod 256
tempSwap = sbox(a)
sbox(a) = sbox(b)
sbox(b) = tempSwap
Next
End Sub
Function EnDeCrypt(ByVal plaintxt As String) As String
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
'::: This routine does all the work. Call it both to ENcrypt :::
'::: and to DEcrypt your data. :::
':::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Dim temp
Dim a
Dim i
Dim j
Dim k
Dim cipherby
Dim cipher, psw
i = 0
j = 0
psw = "encdecpassword"
RC4Initialize(psw)
For a = 1 To Len(plaintxt)
i = (i + 1) Mod 256
j = (j + sbox(i)) Mod 256
temp = sbox(i)
sbox(i) = sbox(j)
sbox(j) = temp
k = sbox((sbox(i) + sbox(j)) Mod 256)
cipherby = Asc(Mid(plaintxt, a, 1)) Xor k
cipher = cipher & Chr(cipherby)
Next
EnDeCrypt = cipher
End Function
#End Region |
