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
-
Framework Laptop 13 Pro Competes with the Best
Framework has released what might be considered the MacBook of Linux devices.
-
The Latest CachyOS Features Supercharged Kernel
The latest release of CachyOS brings with it an enhanced version of the latest Linux kernel.
-
Kernel 7.0 Is a Bit More Rusty
Linux kernel 7.0 has been released for general availability, with Rust finally getting its due.
-
France Says "Au Revoir" to Microsoft
In a move that should surprise no one, France announced plans to reduce its reliance on US technology, and Microsoft Windows is the first to get the boot.
-
CIQ Releases Compatibility Catalog for Rocky Linux
The company behind Rocky Linux is making an open catalog available to developers, hobbyists, and other contributors, so they can verify and publish compatibility with the CIQ lineup.
-
KDE Gets Some Resuscitation
KDE is bringing back two themes that vanished a few years ago, putting a bit more air under its wings.
-
Ubuntu 26.04 Beta Arrives with Some Surprises
Ubuntu 26.04 is almost here, but the beta version has been released, and it might surprise some people.
-
Ubuntu MATE Dev Leaving After 12 years
Martin Wimpress, the maintainer of Ubuntu MATE, is now searching for his successor. Are you the next in line?
-
Kali Linux Waxes Nostalgic with BackTrack Mode
For those who've used Kali Linux since its inception, the changes with the new release are sure to put a smile on your face.
-
Gnome 50 Smooths Out NVIDIA GPU Issues
Gamers rejoice, your favorite pastime just got better with Gnome 50 and NVIDIA GPUs.