Cryptography 8

Question 1

Choose some number by which to shift each letter of the message. ( right is “+” | left is “-“ | A “+2” = C | C “-1” = B ).

Answer 1

Caesar Cipher

Question 2

Rotate all characters 13 letters through the alphabet ( A becomes N, B becomes O … ).

Answer 2

ROT13

Question 3

Use of a rod of a certain length to create/encrypt a message, and same rod must be used to read/decrypt the message by the recipient. Transposition cipher.

Answer 3

Scytale Cipher

Question 4

It is a method of encrypting by using a series of interwoven Caesar ciphers based on the letters of a keyword. It is considered a poly-alphabetic cipher system.

Answer 4

Vigenere Cipher

Question 5

a multi-alphabet substitution cipher using machinery to accomplish the encryption. In World War II, the Germans used this as an electro-mechanical rotor-based cipher system.

Answer 5

The Enigma Machine

Question 6

C = E(k,p)

Answer 6

Symmetric Encryption Formula

Question 7

is a algorithm such that increasing either the block size or key size the resulting function is more secure. A Feistel cipher AKA Fisted Network is used in most block ciphers. The block of plain text is split into two identically sized blocks. A round function is applied to one half and the output of that is then xor’d with the other half. The two blocks are switched. This process can be repeated some number of times. What varies between algorithms is the nature of the round and the number of iterations.

P = E(k,c)

Answer 7

Feistel & Symmetric Decryption Formula

Question 8

(block cipher) - block size 128-bits, 10(128), 12(192), 14(256) rounds, substitution-permutation

Answer 8

AES

Question 9

??? = key size 1-256-bits, up to 255 rounds, Stream Cipher.

??? = 2064 bit state size with 1-2048 key size. 1 round Stream Cipher

??? = uses lagged fibonacci pseudorandom number generator data stream XORed w/a key. Stream Cipher.

??? = revised version of FISH to address known plain text vulnerabilities. Stream Cipher.

Answer 9

Stream Ciphers (RCA, RC4, FISH, PIKE)

Question 10

??? : 256-bit hash function developed by Russian Govt. block size 64-bit.

??? : hash function 192-bit, block size 512-bit

Answer 10

Hash Functions (GOST, TIGER)