Simplify the following text for a Grade 14 native English-speaking person.
Original: A chosen-plaintext attack ( CPA ) is an attack model for cryptanalysis which presumes that the attacker has the capability to choose arbitrary plaintexts to be encrypted and obtain the corresponding ciphertexts .
Simplified: A chosen-plaintext attack ( CPA ) is an attack model for cryptanalysis which assume that the attacker has the capability to choose random plaintexts to be encrypted and obtain the corresponding ciphertexts .