Chosen plaintext attack

Relation to other attacks

However, a chosen-plaintext attack is less powerful than a chosen-ciphertext attack in which the attacker can obtain the plaintexts of arbitrary ciphertexts. A CCA-attacker can sometimes break a CPA-secure system. For example, the El Gamal cipher is secure against chosen plaintext attacks, but vulnerable to chosen ciphertext attacks because it is unconditionally malleable.