Hi I was looking for implementing cryptography in an ASP page.
I found this following article of great use
http://www.4guysfromrolla.com/webtech/010100-1.shtml
The inc file
<%
Dim sbox(255)
Dim key(255)
Sub RC4Initialize(strPwd)
dim tempSwap
dim a
dim b
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(plaintxt, psw)
dim temp
dim a
dim i
dim j
dim k
dim cipherby
dim cipher
i = 0
j = 0
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
%>
And following is the code for my asp page
<!–#include file=”g.inc”–>
<html>
<head>
<title>TestPage</title>
</head>
<body>
<form action=”G.asp” method=”post”>
<%
dim psw, txt
dim strTemp
txt=”NishantRana”
psw=”myPassword”
strTemp=EnDeCrypt(txt,psw)
response.write “Encrypted Text =” & strTemp & “</Br>”
txt=EnDeCrypt(strTemp,psw)
response.write “Decrypted Text =” & txt
%>
</form>
</body>
</html>
Just copy and paste the code
That’s it …
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