Crypt analysis is the art of decryting an encrypted message, in whole or in part, when the decryption key is not known. Depending on the amount of known information and the amount of control over the system by the cryptanalyst, there are several basic types of cryptanalytic attacks

Ciphertext: The adversary only has access to one or more encrypted messages. The most important goal of a proposed cryptosystem is to withstand this type of attack

Brute force attack: This is a type of ciphertext-only attack. It is based on exhaustive key search, and for well-designed cryptosystems, it should be computationally infeasible. By today's standards, 128-bit keys are considered secure against the brute force attack..

Chosen-plaintext attack: Essentially, an adversary can feed the chosen plaintext into the black box that contains the encryption algorithm and the encryption key. The black box produces the corresponding ciphertext, and the adversary can use the accumulated knowledge about the plaintext-ciphertext pairs to obtain the secret key or at least a part of it.

Chosen-ciphertext attack: Here, an adversary can feed the chosen ciphertext into the black box that contains the decryption algorithm and the decryption key. The black box produces the corresponding plaintext, and the adversary tries to obtain the secret key or a part of the key by analyzing the accumulated ciphertext - plaintext pairs.