DES- Encryption

DES follows

• Hash Algorithm

• Caesars Cipher

• Feistel Cipher Structure

• SP Networks

The DES Algorithm Cipher System consists of ____________rounds (iterations) each with a round key

Data Encryption Standard (DES) uses a __________.

• Stream Cipher

• Bit Cipher

• Block Cipher

• Substitution Cipher

In the DES algorithm, although the key size is 64 bits only 48bits are used for the encryption procedure, the rest are parity bits.

• True

• False

In the DES algorithm the round key is __________ bit and the Round Input is ____________bits.

• a) 48, 32

• b) 64,32

• c) 56, 24

• d) 32, 32

In the DES algorithm the Round Input is 32 bits, which is expanded to 48 bits via ____________

• P-box

• Expansion P-box

• S- box

• Expansion S-box

The number of unique substitution boxes in DES after the 48 bit XOR operation are

• 8

• 4

• 6

• 12

In the DES algorithm the 64 bit key input is shortened to 56 bits by ignoring every 4th bit.

• True

• False