Known Ciphertext Attack
A Known Ciphertext Attack is a type of attack in cryptography where an attacker knows or has access to some or all of the ciphertexts (encoded messages) of a cipher. The goal is to use this information to try and deduce the key used to encrypt the messages, and thus break the cipher.
Imagine you have a secret code that you use to send messages to your friend. You encode your message using the secret code, and your friend decodes it using the same code. But if someone else knows some of the encoded messages, they may be able to figure out the code and read all of your future messages.
In the same way, if an attacker knows some of the ciphertexts produced by a cipher, they may be able to use that information to guess the key and read all future messages. This is why it’s important to keep ciphertexts secret, or to use a strong cipher that can resist known ciphertext attacks.
To protect against known ciphertext attacks, cryptographers can use techniques like key rotation, where the cipher’s key is changed frequently, or adding additional random data to each message, making it harder for an attacker to find patterns in the ciphertexts.