Cryptography & Symmetric Key Algorithms

Question 1

Caesar Cipher

Answer 1

1.) Earliest known cypher system used by Julius Caesar to communicate with Cicero in Rome when he was conquering Europe.
2.) ROT3 or Rotate 3. i.e. shift each letter of the alphabet 3 places to the right.
3.) Other names include ROT3, C3. It is monoalphabetic in nature.
4.) Drawback - vulnerable to am attack called ‘frequency analysis’
5.) It is a ‘substitution’ cypher

Question 2

American Civil War

Answer 2

1.) Union and Confederate forces wanted controls to prevent spying on telegraph lines.
2.) Substitution and transposition
3.) Another system used during civil war was a series of flag signals
4.) Flag signals were developed by an army doctor Albert J. Myer

Question 3

Enigma

Answer 3

1.) German military industrial complex adapted a commercial code making machine called Ultra for govt. use
2.) 3 to 6 rotors to implement a ‘substitution’ cipher
3.) Th Germans safeguarded the devices and made it extremely difficult for Allied forces to acquire one

Question 4

Ultra

Answer 4

1.) Allied forces began a top effort known by the code name Ultra to attack the Enigma codes
2.) Polish military successfully reconstructed the Enigma prototype

Question 5

Japanese Purple Machine

Answer 5

1.) similar to Enigma the Japanese developed this purple machine
2.) The code was broken by the end of world war 2
3.) The Americans were aided by the fact that Japanese communicators used very formal message formats that resulted in large number of similar texts in multiple messages therefore easing the cryptanalytic efforts.

Question 6

Four fundamental goals of cryptography

Answer 6

Confidentiality
Integrity
Authentication
Non-repudiation

Question 7

Data at Rest

Answer 7

Data that resides in a permanent location awaiting access.
e.g. data on hard drives, backup tapes, cloud storage devices, USB devices

Question 8

Data in Motion

Answer 8

Also called ‘data on the wire’ refers to data transmitted across a n/w

Question 9

Confidentiality

Answer 9

Data remains private while at rest and in motion

Question 10

Integrity

Answer 10

Ensures data is not modified without authorisation

Question 11

Authentication

Answer 11

Verifies the claimed identity of system users

Question 12

Non repudiation

Answer 12

Provides assurance to the recipient that the message was originated by the sender and not someone masquerading as the sender

Question 13

Kerchoff Principle

Answer 13

1.) The cryptographic system should be secure even if everything about the system except the key is public knowledge
2.) The principle can be summed up as ‘the enemy knows the system’

Question 14

Private key cryptosystems

Answer 14

1.) All participants use a single shared key

Question 15

Public key cryptosystems

Answer 15

1.) Each participant has their own pair of keys

Question 16

Cryptography, Crypto analysis and Ctryptology

Answer 16

1.) Cryptography - creating and implementing secret codes and ciphers
2.) Cryptanalysis - the study of methods to defeat codes and ciphers
3.) Cryptology - together cryptography and cryptanalysis is called Cryptology

Question 17

FIPS 140-2

Answer 17

‘Security Requirements for Cryptographic Modules’ defines the hardware and software requirements for cryptographic modules that federal government uses.