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Posted 19 Jan 2002

, 19 Jan 2002
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Introduction

Do you have a website where users need to login, and when they do you compare the password they enter with a column in a usertable? Some people do logins like this. It's easy to program and it works just fine. But what if someone got hold of the usertable and all the passwords of everyone? You may want to hide or encrypt the passwords in the usertable. Many programming languages have functions to do this. I make ASP-webpages, and I haven't found any quick functions to do this. There are plenty of components to do this, some free of charge even. But what if you cant install components on the webserver

Here is a short and neat way to encrypt your users passwords. You need two strings for it to work. Typically the username and the password.

Code

```Function encrypt(x1, x2)
s = ""
t = 0
For i = 1 to len(x1)
t = t + asc(mid(x1,i,1))
Next
For i = 1 to len(x2)
y = (t + asc(mid(x2,i,1)) * asc(mid(x2,((i+1) mod len(x2)+1),1))) mod 255
s = s & chr(y)
Next
For i = (len(x2) + 1) to 10
If t>598.8 Then t = 598.8
y = t^3*i mod 255
s = s & chr(y)
Next
encrypt = s
End Function```

If you want to test this function you can create an asp-page and upload it to your website. Here's my codelisting to encrypt.asp

```<%
Function encrypt(x1, x2)
s = ""
t = 0
For i = 1 to len(x1)
t = t + asc(mid(x1,i,1))
Next
For i = 1 to len(x2)
y = (t + asc(mid(x2,i,1)) * asc(mid(x2,((i+1) mod len(x2)+1),1))) mod 255
s = s & chr(y)
Next
For i = (len(x2) + 1) to 10
If t>598.8 Then t = 598.8
y = t^3*i mod 255
s = s & chr(y)
Next
encrypt = s
End Function
%>

<html>
<title>Encrypt</title>

<body>
<% If request.form("name") = "" Then %>
<form action="encrypt.asp" method="post">
<input type="text" name="name"><input type="text" name="pass">
<input type="submit">
</form>
<% Else  %>
<% response.write encrypt(request.form("name"),request.form("pass")) %>
<% End If %>
</body>
</html>```

Remarks

• The function is not reversible, so there is no way to take the result and reverse it into the password. You will need to recreate the password with a new one (some users seem to forget their passwords and always wants it retreieved)
• This is not a high-level encryption, but its good enough to hide it from lame hackers (hehe).
• The password is always sent from the user inputpage to the page encrypting it. Somewhere in between a hacker can fetch it. Secure zones (SSL) can remedy this.
• Feel free to use the code to whatever you like. But if you alter it make a post in the thread related to this article so we all can share the fun.

A list of licenses authors might use can be found here

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 Web Developer Norway
Tommy live in Tromsø, a city far up north in Norway. He does programming and webdevelopment for a living.

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 FirstPrev Next
 Security of the algorithm John Rayner21-Jan-02 2:24 John Rayner 21-Jan-02 2:24
 Re: Security of the algorithm skaue21-Jan-02 3:34 skaue 21-Jan-02 3:34
 Re: Security of the algorithm Jonas Elfstrom29-Jan-02 23:41 Jonas Elfstrom 29-Jan-02 23:41
 hashing is already in asp.net Johan Danforth10-Jan-03 2:10 Johan Danforth 10-Jan-03 2:10
 Re: hashing is already in asp.net tommy skaue10-Jan-03 2:14 tommy skaue 10-Jan-03 2:14
 A note from the author skaue21-Jan-02 2:16 skaue 21-Jan-02 2:16
 Re: A note from the author James Curran21-Jan-02 3:42 James Curran 21-Jan-02 3:42
 Re: A note from the author skaue21-Jan-02 3:50 skaue 21-Jan-02 3:50
 Yes, you're right. I have to admit that the article was submitted in a hurry. The reason I need to check t's value is that vbscrips variables has a max value of 2.147.483.647 and when powering t (t^3) it may exceed that value in just that expression... I would move the test just after the first loop like this: Function encrypt(x1, x2) s = "" t = 0 For i = 1 to len(x1) t = t + asc(mid(x1,i,1)) Next If t>598.8 Then t = 598.8 For i = 1 to len(x2) y = (t + asc(mid(x2,i,1)) * asc(mid(x2,((i+1) mod len(x2)+1),1))) mod 255 s = s & chr(y) Next For i = (len(x2) + 1) to 10 y = t^3*i mod 255 s = s & chr(y) Next encrypt = s End Function Thanks James
 Re: A note from the author James Curran21-Jan-02 3:49 James Curran 21-Jan-02 3:49
 Re: A note from the author skaue21-Jan-02 3:56 skaue 21-Jan-02 3:56
 Re: A note from the author Matthias Mann21-Jan-02 8:32 Matthias Mann 21-Jan-02 8:32
 Re: UPDATED CODE skaue21-Jan-02 5:53 skaue 21-Jan-02 5:53