In which of the following cryptographic attacking techniques does an attacker obtain encrypted messages that have been encrypted using the same encryption algorithm?

A chosen-plaintext attack (CPA) is an attack where the attacker can choose arbitrary plaintexts to be encrypted and obtain their corresponding ciphertexts.

A chosen-ciphertext attack (CCA) is an attack where the attacker can choose arbitrary ciphertexts to be decrypted and obtain their corresponding plaintexts.

In a ciphertext-only attack, the attacker exclusively possesses encrypted messages (ciphertexts) and knows the encryption algorithm used, but lacks any knowledge of the original plaintexts. The objective is to deduce the secret key or recover the original plaintext from these ciphertexts alone.

A known-plaintext attack (KPA) is an attack where the attacker has access to a collection of ciphertexts and their corresponding plaintexts.