What Is Initialization Vector?

You're probably familiar with this concept: you have a secret key, and it's stored in your safe. You also have a big pile of gold coins and want to keep them safe from thieves. So what do you do? You put the gold coins in the safe and lock them up. There's a problem: how do you know someone can't just break into your house and steal the combination for the safe? That's where an initialization vector (IV) comes in. Let's say that each time you use your variety to open the safe, you leave an IV out on your coffee table—something like "IV1," "IV2," "IV3," etc. The next time someone breaks into your house and tries to get into the safe, they'll see those IVs on your coffee table and think they know what they are (they don't). When they return to try opening the safe later, they'll have forgotten what IV got them in last time! Then they'll realize that even though they thought they knew what IV would bring them inside, they didn't—because now new IVs are sitting on top of those old ones. An initialization vector is like a secret handshake for data encryption. It's not used to encrypt the message itself; it's additional information you add to the plaintext when encrypting it with a block cipher. The IV isn't part of the ciphertext and doesn't get encrypted with the rest of your message. Using an initialization vector avoids repetition during the encryption process, making it impossible for hackers who use dictionary attacks to decrypt the exchanged encrypted message by discovering a pattern. You can think of this as hiding something under a rock. If someone were trying to find out what was hidden there, they'd be able to see some rocks sticking up above ground level (the unencrypted parts), but they would need to find out which one had your secret treasure underneath. It was because each rock was identical!