Skipjack (cipher)

In cryptography, Skipjack is a block cipher—an algorithm for encryption—developed by the U.S. National Security Agency (NSA). A block cipher is a way to scramble information so that only someone with the right key can read it again. Skipjack was created to help protect secret data by turning it into a form that looks random and unreadable.

At first, the details about how Skipjack worked were kept secret, which means only certain people were allowed to know. This made it a classified piece of technology. It was planned to be used in a special computer chip called the Clipper chip, which was designed to balance security with government oversight.

Later on, the information about Skipjack was made public, a process known as being declassified. This allowed everyone to learn about how the cipher worked and study its strengths and weaknesses. Skipjack became an important example in the study of encryption and how governments approach digital security.

History of Skipjack

Skipjack was created as a way to encrypt information for the U.S. government. It was meant to be used in a special chip called the Clipper chip, which had special protection to prevent tampering. The way Skipjack worked was kept secret at first, which made many people uneasy.

In 1998, the government decided to make Skipjack public. Before that, experts outside the government looked at how Skipjack worked and found it to be safe and reliable. Skipjack was developed by the U.S. National Security Agency and used ideas from older encryption methods. By 2016, official U.S. standards no longer approved Skipjack for government use.

Description

Skipjack is a special kind of code used to hide information, called a block cipher. It uses an 80-bit key to lock and unlock 64-bit pieces of data. This method, known as an unbalanced Feistel network, has 32 steps to keep the information safe, and it was once planned to be used in secure phones.

Cryptanalysis

Researchers found ways to break parts of the Skipjack cipher not long after it was made public. They showed attacks on most of the cipher's steps, though these were not much faster than simply trying every possible key.

Later, a claim was made that the entire cipher could be broken, but in 2009, it was clarified that no effective attack on all 32 steps of Skipjack was known at that time.

In pop culture

The algorithm named Skipjack appears in the back-story of Dan Brown's 1998 novel Digital Fortress. In the story, Skipjack is suggested as a new way to secure messages online, but it secretly includes a hidden way for the NSA to unlock messages.

In the video game modification Dystopia for Half-Life 2, an "encryption" program uses Skipjack along with another method called Blowfish to protect information in a virtual world.