True or false: CBC-mode encryption with PKCS #7 padding provides message integrity, as long as the receiver makes sure to verify the padding upon decryption.

Assume CBC-mode encryption using an 8-byte (64-bit) block cipher. Say a sender encrypts the 8-byte message “sendme$2” (encoded in ASCII), resulting in ciphertext 0xFF 09 28 30 8C 93 81 06 39 D0 81 5A 07 79 17 43. Which of the following ciphertexts will decrypt to the message “sendme$4” ?

Assume a sender and receiver use the encrypt-and-authenticate approach for variable-length messages, using CTR-mode encryption and a variant of CBC-MAC secure for authenticating variable-length data (and independent keys for each). Which of the following statements is true?

? Alternatively, what is the remainder when 128 raised to 128 is divided by 7?

Define the generator G by G(x) = x | x. (G maps inputs of length n to outputs of length 2n). Which of the following algorithms A distinguishes the output of G from uniform?

Which of the following BEST describes the security offered by the Diffie-Hellman key-exchange protocol (assuming the DDH problem is hard)?

Which of the following is a drawback of the private-key setting that is NOT addressed by the public-key setting?

What is the size of key space |K| for a shift cipher, considering the message space as English alphabets, and encryption algorithm as Enc​(m)=(m+shift)mod 26?

If the message “cryptoisfun” is encrypted with the shift cipher and key 25. What is the resulting ciphertext?

Say G is in the subgroup Z*11, generated by g = 4. Let’s say, the group has order 5.  The public key contains h = 3. What is encryption of the message m = 5, using the secret exponent y = 3?