Messages in this thread | | | Date | Thu, 26 Feb 1998 11:10:26 +0100 | From | Thomas Pornin <> | Subject | Re: Is there any way... |
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In article <Pine.LNX.3.96.980224132847.2040A-100000@darkstar.phystech.com> you write: >I need to generate some unique number or string >based on real user ID of the process, so >that >1. the number is independent of OS version >2. reproducible >3. other user ID would not be able to generate > the same number even if he got a hold on > a source code
A way could be the following: write a kernel module that contains a secret key K and implements md5; this modules attaches itself to a device that will return, when read or ioctled, the result of md5(getuid(),K). All you need is to maintain the binary secret (that means chmod 600 on the .o); the sources may be distributed freely. You may insert it anytime, with kerneld for instance.
The /dev/random linux code uses md5, so you will easily find some code to copy.
I see no way to do it without some secret key. After all, if there was no secret, a user could reproduce the system on his own home-linux-PC.
--Thomas Pornin
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