December 2000
Intermediate to advanced
800 pages
22h 41m
English
Content preview from Special Edition Using Linux®, Sixth Edition
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Encryption and Authentication
Originally, all Linux (and UNIX) systems used /etc/passwd to hold the username/password pair needed to authenticate a user and permit access. The password was saved as a DES (Data Encryption Standard) hash to prevent anyone from reading the actual password. DES uses a 13-character field, the first two characters acting as a salt for the DES algorithm.
The salt acts as a random number passed to the encrypting algorithm. Each salt will produce a different encryption for a particular password, so even if 100 users choose the same (obviously bad) password, examining the encrypted field would not make this apparent as long as each had a different salt. (Microsoft does not use this approach, so examining the encrypted ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.