Shared secret facts for kids

A shared secret is like a special code word or password that only certain people or computers know. Imagine you want to send a secret message to a friend, and you don't want anyone else to read it. A shared secret helps you keep your messages private and safe.

This secret can be a simple password, a longer phrase, or even a very big, random number that computers use. It's a piece of information that helps two or more parties communicate securely without others understanding what they are saying.

How Shared Secrets Work

Shared secrets are super important for keeping online communication safe. They help make sure that only the right people can access information.

Getting the Secret

There are a couple of ways people or computers get a shared secret:

• Pre-shared: Sometimes, the secret is agreed upon *before* any communication starts. Think of it like you and your friend deciding on a secret handshake before you meet up. This is called a "pre-shared key."
• Created on the fly: Other times, the secret is created right when the communication begins. This happens using clever computer methods called "key-agreement protocols." These protocols allow two parties to create a secret together, even if they've never met or shared a secret before! Famous examples include:

* Diffie-Hellman: This is a way for two parties to agree on a secret number over an insecure connection, without anyone listening in being able to figure out the number. * Kerberos: This is like a trusted ticket system. It helps computers prove who they are to each other and then get a shared secret to talk privately.

What Shared Secrets Are Used For

Shared secrets have a few main jobs:

• Proving who you are: When you log in to a website or an app, you often use a shared secret (your password) to prove that you are really you. This is called "authentication." Sometimes, systems use a "challenge-response" method, where the computer asks you a question, and your shared secret helps you give the correct answer.
• Making new keys: The shared secret can be used to create even more secret keys. These new keys are then used for:

* Encryption: This is like scrambling your messages so that only someone with the right key can unscramble and read them. * Message authentication: This helps make sure that a message hasn't been changed or tampered with while it was being sent. It also confirms that the message came from the person you expect.

Keeping Keys Unique

To make sure every conversation is super secure, the shared secret is often mixed with another piece of information called an "initialization vector" (IV). An IV is a random number used only once. Mixing the shared secret with an IV helps create unique "session keys" for each new conversation or message. This makes it much harder for anyone to guess or break the codes.

An example of this is a method called "derived unique key per transaction," which means a new, unique key is made for every single action or message.

See also

In Spanish: Secreto compartido para niños