SafekipediaIn cryptography, CAST-128 (also called CAST5) is a special way to keep information safe, called a symmetric-key block cipher. It has been used in many products, like some versions of GPG and PGP. It was even approved for use by the Government of Canada after being checked by the Communications Security Establishment.
The idea for CAST-128 came in 1996 from two people, Carlisle Adams and Stafford Tavares. They used something called the CAST design to create it. There is also a related cipher called CAST-256, which was one of the options for a big global safety standard called AES.
CAST-128 works in steps called rounds—either 12 or 16 of them. It deals with pieces of data that are 64-bit in size and can use keys that are between 40 and 128 bits long. The way it works includes special boxes called S-boxes, mixing up bits in different ways, and adding or subtracting numbers. Even though a company called Entrust has a patent on the basic idea, anyone can use CAST-128 for free, whether for business or just personal use.
This article is a child-friendly adaptation of the Wikipedia article on CAST-128, available under CC BY-SA 4.0.
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