1. Public-Key Encryption is based on a reverse-ECC, written on one-time pads, with limited entropy, and extended ASCII, powered by AES, using Double and Triple DES signatures. This prime modularity is conditioned by the "Weakest link" principle, that insures non-conflicting quantum bits, and is based on fully transposed bits commensurate with non-repudiating ciphertext intervals.
The above statement is:
a. a logical result from the discovery of Rivest, Shamir and Adelman, the RSA team.
b. True for only rare occasions
c. True for decryption, not for encryption
d. Utter nonsense
2. A message that was encrypted with DES, cannot be re-encrypted with RSA because DES is a symmetric cipher, and RSA is asymmetric. AES is symmetric like DES, but its key size is larger and therefore it too cannot be used for re-encryption.
Which of the responses below fits?
a. true, re-encryption can only be done with the same cipher that performed the original encryption.
b. to encrypt a message is to turn it upside down, if you do it twice you get it back up again, so re-encryption makes no sense any which way.
c. True but useless. The opposite makes sense: you can re-encrypt with DES a message that was pre-encrypted with RSA!
d. False. One can re-encrypt any data regardless of its source, and even re-encrypt once more!
3. If you add two bits to a cryptographic key, you make it four times more difficult to guess it correctly.
The above statement is:
a. false: cryptographic keys are built from bytes, not bits.
b. true only if the key has 4 bits before adding the extra two.
c. false. adding two bits is making very little difference in how difficult it is to guess a typical large key.
d. correct, because every bit can have one of two values.
4. A Hollywood studio, having heard you just graduated from cryptography class asks your professional opinion regarding the following plot: the bad guy sells his victim a public version of RSA along with an encryption key, then he prevails on his victim to encrypt with it all his personal data and erase the plain version. Later he extorts the victim, demanding a fortune to receive his decryption key, otherwise he would lose access to his own data. The studio wonders if the script makes any technical sense.
Which of the following answers to the studio will make your professor proud?
a. the script preparer does not know what he is talking about.
b. from a crypto point of view this script is OK.
c. makes no sense. The victim could readily acquire the RSA public key and readily decrypt his personal data.
d. As written it's not scientific, but if the preparer would use Diffie Hellman, it will be OK.