Week 4 (Security in the Data Domain)

Question 1

Name the 7 Security Domains.

Answer 1

Organization, End-Users, Physical Access, System, Software, Network, Data

Question 2

Explain Scytale.

Answer 2

It is one of the oldest military ciphering methods used in 400 BC - Used by the Spartans.
It is the method of using a narrow strip of leather or cloth going around a cylindrical rod and the message is written across the adjoining sides.

Question 3

What is Cryptography?

Answer 3

Scrambling information so it appears unreadable. It Transforms information into secure form.
Science of transforming information into a secure form while being transmitted or stored.

Question 4

What is Encryption and Decryption?

Answer 4

Encryption: Changing original text into a secret message using cryptography.
Decryption: Changing secret messages back into original form.

Question 5

What is Plaintext and Ciphertext?

Answer 5

Plaintext: is the Data to be encrypted. It is input into an encryption algorithm.
Ciphertext: Data that was encrypted.

Question 6

What is a key?

Answer 6

A key is a mathematical value entered into the algorithm to produce ciphertext and vice versa.

Question 7

What are the five basic information protections Cryptography can provide?

Answer 7

Confidentiality,
Integrity,
Availability,
Authenticity of the Sender, and
Nonrepudiation.

Question 8

How does Cryptography provide Confidentiality?

Answer 8

It ensures only the authorized parties can view the data. Encrypted information can only be viewed by those who have been provided the key.

Question 9

How does Cryptography provide Integrity?

Answer 9

Ensures information is correct and unaltered. Encrypted information cannot be changed except by authorized users who have the key.

Question 10

How does Cryptography provide Availability?

Answer 10

Authorized users can access it. Authorized users are provided the decryption key to access the information.

Question 11

How does Cryptography provide Authenticity of the Sender?

Answer 11

It refers to the proven fact that something is legitimate or real. Cryptography can prove the sender was legitimate and not an imposter.

Question 12

How does Cryptography provide Nonrepudiation?

Answer 12

Proves that a user performed an action. Cryptographic nonrepudiation prevents an individual from fraudulently denying they were involved in a transaction.

Question 13

Explain Symmetric Encryption Algorithms.

Answer 13

It uses the same shared secret key to encrypt and decrypt information. The Secret key cannot be made public and must only be known to the sender and receiver.
Needs to use a secure channel to distribute the key.
It performs faster than most public key cryptographic algorithms.

Question 14

Explain Asymmetric Encryption Algorithms.

Answer 14

Also known as public key cryptography.
Uses two mathematically related keys.
Public key available to everyone and freely distributed.
Private key known only to individual to whom it belongs.
Only the Private key can decrypt what has been encrypted with the Public key and vice versa.
Key pairs. For every additional user, there is an additional keypair.

Question 15

What are the mathematical equations for number of keys for both Symmetric and Asymmetric Algorithms?

Answer 15

Symmetric: N(N-1)/2, where N is the number of users and N-1 is the number of additional links.
Asymmetric: 2N, where N is the number of users.

Question 16

What are the two symmetric algorithm categories?

Answer 16

Based on the amount of data processed over time:
Stream cipher: Encrypts data one bit (or character) at a time as it becomes available.
Block Cipher: Works on entire block of plaintext at a time. Separate blocks of 8 to 16 bytes encrypted independently, and the blocks are randomized for additional security.

Question 17

What are two types of Ciphers?

Answer 17

Substitution Cipher - Caesar Cipher - moves the letters up the alphabet by a specific number of letters
Transposition Cipher - Rearranges letters without changing them.

Question 18

Explain the Transposition Cipher.

Answer 18

Rearranges letters without changing them.
Lowercase letters has Higher Precedence in the Key.
Determine Key
Assign number value
Record plaintext by row.
Extract by column

Question 19

Final Step in most symmetric ciphers?

Answer 19

Combine Cipher Stream with Plaintext to create the ciphertext.

Question 20

Give examples of Symmetric Algorithms.

Answer 20

Data Encryption Standard (DES)
Triple Data Encryption Standard (3DES) - Uses three rounds of encryption, ciphertext of first round becomes input for second iteration, most secure versions use different keys used for each round.
Advanced Encryption Standard (AES) - Performs three steps on every block of plaintext, designed to be secure well into the future.
RC4
Rivest Cipher (RC)
International Data Encryption Algorithm (IDEA) - block cipher processing 64 bits with a 128-bit key with 8 rounds.
Blowfish - Block cipher operating on 64-bit blocks with key lengths from 32-448 bits. No significant weaknesses have been identified.

Question 21

Popular Asymmetric algorithm:

Answer 21

RSA
2048, 1024

Question 22

Explain Hash Algorithms.

Answer 22

A cryptographic hash algorithm produces an irreversible fixed length string or hash from a variable length message.
It is extremely unlikely that different messages produce the same hash value.
Used for confidentiality (to store passwords securely) and for authentication, nonrepudiation, and integrity (as part of a digital signature)

Question 23

What are some common Hash Algorithms?

Answer 23

Message Digest 5 (MD5)
Secure Hash Algorithm (SHA)

Question 24

Explain the Digital Signature.

Answer 24

Private key to Encrypt, Public Key to Decrypt. (This is the only case the Private key is used to encrypt the message)
Verifies the sender (Authenticity)
Used to prove a document originated from a valid sender
Prevents sender from disowning the message (nonrepudiation)
Proves message integrity

Question 25

Explain Stenography.

Answer 25

Hiding the existence of data
Embedding messages into image, audio, or video files
Achieved by dividing data and hiding in unused portions of the image
Invisibly altering the structure of a digital image

Question 26

What is hashing used for?

Answer 26

Only for comparisons - hash the message one side then hash the message the other side and compare.

Question 27

Cryptography can be applied through:

Answer 27

Hardware or Software