Symmetric Encryption & Message Confidentiality

Encryption transforms readable plaintext into:

For secure symmetric encryption, what must be kept secret?

In a cipher that rearranges the elements of the plaintext, the operation used is:

If both sender and receiver use the SAME key, the system is called:

What is the effective (true) key length of DES?

What is the main reason DES is no longer considered secure?

What block size and key lengths does AES support?

Which cipher mode produces the SAME ciphertext for identical plaintext blocks, making it weak for long messages?

A stream cipher XORs plaintext P = 1011 with keystream K = 1101. What is the ciphertext C, and how is it decrypted?

Which is an advantage of CTR (Counter) mode?

The security of a strong cipher should depend on keeping the algorithm secret.

A larger, more random keyspace makes it harder for an intruder to guess the key.

A block cipher processes the plaintext one element at a time, continuously.

DES was issued in 1977 as FIPS 46 by NIST.

DES applies 16 rounds of transposition and substitution to each block.

3DES is permitted only for legacy systems, while single-DES is the algorithm of choice.

AES is based on the Rijndael algorithm, designed by Joan Daemen and Vincent Rijmen.

CBC mode produces more random ciphertext than ECB because of block chaining.

Nonces are used in authentication protocols to help prevent replay attacks.

There is a definitive test that can prove a sequence of numbers is truly independent.

Match each classification dimension with its options.

Match each block cipher with a key fact.

Match each cipher mode with its property.

Match each term with its meaning.

Match each randomness criterion with its meaning.