Here is an article that explains the concept of child keys in BIP32 in a way that is easy to understand, even for a 5-year-old:
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What’s going on under the hood when we talk about Bitcoin and Ethereum wallets?
Imagine having a super secret box where you keep your favorite toy. You want to share it with a friend, but you don’t want anyone else to know what’s inside.
In digital wallets like Bitcoin and Ethereum, there are special “keys” that help control access to the toy (wallet). But how does it work?
Let’s talk about two types of keys: Child-Child and Child-Child Strengthened.
Child Keys
Imagine your friend wants to borrow your secret box. You say, “Okay, you can take a look inside, but just for a minute.” It’s like giving them a baby key.
A child key is a copy of the original key that doesn’t contain all the information about the toy (wallet). Think of it as a simplified version of the toy. This child key is for borrowing things from the owner, but not for storing actual toys.
Child-Strengthened
Now imagine your friend comes back and says, “Hey, I borrowed your secret box, but now I have to keep it safe!” Say, “Okay, here’s a reinforced child lock. “All the information about my toys (wallet) is included here.”
A reinforced child key is just like the original key! It’s a special version that includes all the information about the toy (wallet). But unlike a regular Child-Key, a reinforced Child-Key can’t be easily copied or shared with others.
Why are they different?
Think of it this way: if someone had a really long password to access your secret box, a child key would only give them access for a minute. A child lock wouldn’t protect the toy (wallet) itself.
But when you create a hardened child key, you create a special key that can only be used with the actual toy (wallet). This way, even if someone gets a copy of your Hardened Child key, they won’t be able to access all of your toys (wallets).
In BIP32
Bitcoin Improvement Proposal 32 (BIP32) is a set of rules for creating and managing digital wallets. In BIP32, child keys are generated based on the parent key (the original key). The idea is that when you create a wallet, you can choose to use either a child key or a hardened child key.
When you generate a child key, it’s like creating a simplified version of the toy (wallet). But if you want to keep all of your toys (wallets) safe, you need to use a hardened child lock.
So, to summarize: child keys are like simplified versions of the original key, while hardened child keys are like the original key itself. They are designed to protect your digital assets from unauthorized access and sharing.
Hope it helps!
