CHAPTER 2: CLASSICAL ENCRYPTION TECHNIQUES

1. __________ techniques map plaintext elements (characters, bits) into ciphertext elements.

A) Transposition B) Substitution

C) Traditional D) Symmetric

2. Joseph Mauborgne proposed an improvement to the Vernam cipher that uses a random key that is as long as the message so that the key does not need to be repeated. The key is used to encrypt and decrypt a single message and then is discarded. Each new message requires a new key of the same

length as the new message. This scheme is known as a(n) __________ .

A) pascaline B) one-time pad

C) polycipher D) enigma

3. An original intelligible message fed into the algorithm as input is known as _________ , while the coded message produced as output is called the __________ .

A) decryption, encryption B) plaintext, ciphertext

C) deciphering, enciphering D) cipher, plaintext

4. Restoring the plaintext from the ciphertext is __________ .

A) deciphering B) transposition

C) steganography D) encryption

5. A __________ attack involves trying every possible key until an intelligible translation of the ciphertext is obtained.

A) brute-force B) Caesar attack

C) ciphertext only D) chosen plaintext

6. Techniques used for deciphering a message without any knowledge of the enciphering details is ___________ .

A) blind deciphering B) steganography

C) cryptanalysis D) transposition

7. The ___________ takes the ciphertext and the secret key and produces the original plaintext. It is essentially the encryption algorithm run in reverse.

A) Voronoi algorithm B) decryption algorithm

C) cryptanalysis D) diagram algorithm

8. If both sender and receiver use the same key, the system is referred to as:

A) public-key encryption B) two-key

C) asymmetric D) conventional encryption