RC2 facts for kids
RC2 is a special type of secret code, also known as a symmetric-key block cipher, used in cryptography. It was created by a person named Ronald Rivest in 1987. The "RC" in RC2 stands for "Rivest Cipher" or sometimes "Ron's Code."
This code works by taking information in blocks, or chunks, of 64 bits at a time. It uses a special key that can be different lengths, and it processes the information through 18 steps, called "rounds," to make it secret.
How RC2 Works
RC2 uses a special process to scramble information. It has 18 steps, or rounds, that are done in a specific order. These rounds are like different stages of mixing up the data.
The steps are:
- First, it does 5 "mixing rounds."
- Then, it does 1 "mashing round."
- Next, it does 6 more "mixing rounds."
- After that, it does another "mashing round."
- Finally, it finishes with 5 more "mixing rounds."
RC2 also has a "key-expansion algorithm." This means it takes the secret key you give it and turns it into a much longer, more complex key. This longer key has 64 smaller parts, each 16 bits long. Each "mixing round" involves doing a special "mix-up" transformation four times, as you can see in the diagram. A "mashing round" adds one of the 16-bit parts of the expanded key to the data.
How RC2 Was Developed
The creation of RC2 was paid for by a company called Lotus. They wanted a special code to use in their software, Lotus Notes, so they could send it to other countries. The NSA, a government group, looked at the code. They suggested a few changes, and Ronald Rivest added them. After more talks, the code was approved for use outside the US in 1989.
RC2 and Security
For a while, RC2, along with another code called RC4, was allowed to be exported from the US if it used a 40-bit key. However, these 40-bit codes are now considered old and not safe. This is because they can be easily broken by powerful computers using something called a brute force attack. A brute force attack is like trying every possible key until you find the right one.
RC2 can also be broken by a "related-key attack." This is a special way of trying to find the secret key by looking at how the code works with different, but related, keys.
Secret No More
At first, the details of how RC2 worked were kept secret by the company RSA Security. But on January 29, 1996, someone secretly posted the code for RC2 on the Internet. This happened on a public discussion board called Usenet, in a group about secret codes. It's not known if the person who posted it had the original plans or if they figured out how the code worked by studying it (this is called reverse engineering).
See also
In Spanish: RC2 para niños
