Context

Your task is to analyze the following general theoretical statements about cryptography.

Claims

$1.\backslash$geoquad Cryptography deals with methods of breaking codes.

$2.\backslash$geoquad Cryptography and coding theory are different names for the same topic.

$3.\backslash$geoquad Cryptoanalysis deals with the construction of new codes.

$4.\backslash$geoquad We call the output of plaintext encryption a code.

$5.\backslash$geoquad By deciphering the code, we get the key.

$6.\backslash$geoquad Symmetric cryptography uses the same key for encryption and decryption.

$7.\backslash$geoquad Asymmetric cryptography uses the same key for encryption and decryption.

$8.\backslash$geoquad The code key serves us only for encryption.

$9.\backslash$geoquad The code key is only used for decryption.

$10.\backslash$geoquad The cryptosystem consists exclusively of message space $($open texts$),$ cipher space and space

keys.

$11.\backslash$geoquad Cryptographic systems are used exclusively for secrecy of communication.

$12.\backslash$geoquad The cryptosystem consists exclusively of encryption and decryption functions.

$13.\backslash$geoquad An encryption system should not imply secrecy and should not be a problem if it falls into

enemy hands.

$14.\backslash$geoquad The goal of an attack on a cryptosystem is $($primarily$)$ key reconstruction.

$15.\backslash$geoquad Some keys can only be reconstructed by knowing the ciphers.

$16.\backslash$geoquad Cryptographic systems are completely secure and cannot be broken.

$17.\backslash$geoquad A brute$-$force attack involves trying all possible keys until the correct one is found.

$18.\backslash$geoquad Communication is certainly secret if a good cryptosystem is chosen.

$19.\backslash$geoquad Communication is certainly secret if a good cryptosystem is chosen and used correctly.

$20.\backslash$geoquad Cryptosystems in standard libraries of programming languages are always well implemented.

$21.\backslash$geoquad Implementing your own cryptosystem is always a bad idea.

$22.\backslash$geoquad Monoalphabetic codes concern only the Latin alphabet.

$23.\backslash$geoquad Monoalphabetic ciphers always encrypt the symbol in the same way regardless of its position in the text.

$24.\backslash$geoquad Polyalphabetic codes always encode a symbol in the same way regardless of its position in the text.

$25.\backslash$geoquad Different cryptographic algorithms have different strengths and weaknesses.

$26.\backslash$geoquad All modern cryptographic systems are based on classical methods.

$27.\backslash$geoquad We call a cipher symmetric if its message space is identical to the cipher space.

$28.\backslash$geoquad We call a cipher symmetric if encryption and decryption use the same key.

$1$