Hashes, salt, and pepper
Salt and Pepper
© Lead Image © topnat, 123RF.com
Cryptographic hash functions help you protect your passwords, but hashing is only secure if properly understood.
Hash functions are an integral part of computer science – and not just with databases and checksums. Hashes were originally intended for storing data efficiently in memory, but the hashing concept has evolved into a technique for securely storing passwords.
Linux writes the password hash values to the /etc/shadow file, which you can only read if you have root privileges. But even if you have the root password, you'll find it difficult to learn any useful access information. The function used to store the password hash values in etc/shadow is a one-way function, which means you can't work backward from the hash value to create the original password – at least in theory. As you'll learn in this article, attackers still sometimes manage to crack these supposedly irreversible hash functions.
What is a Hash?
The idea of a hash is simple: An address is calculated from the value that is to be stored. Suppose, for example, you need to store the four user names Fritz, Laempel, Max, and Moritz. A hash function would calculate a numeric value from these names.
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.
News
-
Kubuntu Focus Goes Ultra
The Kubuntu Focus team has upped the performance ante of its M2 and Zr laptops with the latest, greatest CPUs from Intel.
-
Linux Gamers May Soon See Less Mouse Lag in KDE Plasma
Gamers using KDE’s Plasma desktop have been suffering from a slight input delay in mouse movement that could lead to getting fragged.
-
Three Lines of Code Improve Linux Storage Performance
A developer changed three lines of code, giving Linux storage performance a 5% bump.
-
AUR Hit Again with Malicious Packages
Once again the Arch User Repository is plagued by a high volume of malicious packages.
-
Alpine Linux 3.24 Features Fresh Desktops and a Newer Kernel
If you're a fan of Alpine Linux, it's time to upgrade because the latest version has been released with KDE Plasma 6.6, Gnome 50, and Linux kernel 6.18 LTS.
-
EU Open Source Strategy Plays Key Role in Tech Sovereignty Package
Comprehensive measures adopted by the European Commission aim to reduce dependency on non-EU countries.
-
Linux Foundation Report Indicates AI Driving Tech Hiring
Within growing security and skills gaps, AI has been found to be a positive driving force behind tech hiring trends in Europe.
-
United Nations Open Source Portal Goes Live
A new open source portal seeks to coordinate and scale open source efforts across the United Nations system.
-
KDE Linux Drops AUR
KDE Linux developers have dropped the Arch User Repository from the build pipeline due to security concerns; other distributions should consider doing the same.
-
California May Exempt Linux from Its Age-Verification Law
After backlash from the Linux community, California may be backing off on its promise to force all operating systems to verify age, but one platform may still have to comply.