On Sep 21, 2006, at 2:48 PM, Alvaro Abril - Tecnologia wrote:
I use applications .exe and .txt files. But .txt files is not secure,
because the people see and change information easily. I need files
with more
security conditions. What I need to use?
To prevent changes, use a MAC. This is a "Message Authentication
Code". You can find this in wikipedia.
You can made a simple MAC function with the MD5() function. The MD5
() function does not require the Revolution encryption capability, it
comes with any release. You need to have a secret string that is
hidden in your script or hidden in the user key (serial number).
Your MAC function can take the string to be tested and the secret
code and return the base64Encode() of the MD5() of the concatenation
of the two strings.
From that make a function got generate file data from inside data by
adding a line with the MAC. Also make a function that checks the MAC
at the end of a file. Use those to check that the data has not been
modified.
If you also want to hide the data, you need to also (on the outside
of all that) encrypt it. That is easiest with the Revolution
encryption library, but you can use command line tools or make a
simple hiding function using the MD5() function. If you do not think
people will spend more than a few seconds on trying to read it, you
can even make a simple function like the classic rot13 function.
Dar
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