known plaintext attack (KPA)

The Known Plaintext Attack (KPA) is characterized by the fact that the attacker knows parts of the transmitted plaintext and derives the secret key from it.

In the case of such attacks, it must be assumed that transmissions on the Internet are made using the HTTP protocol and that the ciphertext has a certain format and contains certain commands and instructions that are repeated with a certain frequency. The attacker can derive the ciphertext commands and the plaintext from it. Therefore, to protect the transmissions from KPA attacks, the encryption should use the longest possible key.