B11 - Cryptography

Question 1

What is encoding?

Answer 1

PRESERVATION - The process of transforming data into such a format that it can be by a different type of system using publicly available algorithms.

Question 2

What is encryption?

Answer 2

OBFUSCATION - The process to encode data securely such that only the authorized user who knows the key or password is able to retrieve the original data for everyone else it is just rubbish.

Question 3

Examples of common encrypted algorithms:

Answer 3

AES, RSA, DES, RC4 Blowfish, Triple DES, Twofish

Question 4

Examples of common encoding algorithms:

Answer 4

Base64, ASCII, UNICODE, URL encoding

Question 5

What is the difference between encryption and encoding?

Answer 5

Encryption requires a secret key and not reversible without it, whereas encoding mean it uses a predefine scheme to convert data from one form to another with no key e.g. base64.

Question 6

What does DES stand for?

Answer 6

Data Encryption Standard

Question 7

What is DES?

Answer 7

Symmetric algorithm that uses a key and the same key to decrypt the message.

Question 8

What is the key and bit size of DES?

Answer 8

KEY: 56 bits, BLOCK: 64 bits.

Question 9

What does 3DES, TDEA or TRIPLE DEA stand for?

Answer 9

Triple Data Encryption Algorithm

Question 10

What is3DES, TDEA or TRIPLE DEA?

Answer 10

Symmetric block cipher that applies DES cipher algorithm three time to each data block

Question 11

What is the key and block size of 3DES, TDEA or TRIPLE DEA?

Answer 11

KEY:168, 122 or 56 bits, BLOCK: 64 bits.

Question 12

What does AES stand for?

Answer 12

Advanced Encryption Standard

Question 13

What is AES?

Answer 13

Symmetric block cipher that secures data by converting it into unreadable format without the proper key.

Question 14

What is the key and block size of AES?

Answer 14

KEY: 128, 192 and 256 bits, BLOCK: 128

Question 15

What does RSA stand for?

Answer 15

Asymmetric algorithm that used two keys: a public key for encryption and a private key for decryption.

Question 16

What is the key size of RSA?

Answer 16

2048 and 4096 bits

Question 17

What does RC4 stand for?

Answer 17

Rivert Cipher 4

Question 18

What does RC4 do?

Answer 18

Symmetric stream cipher which encrypts one byte at a time. - Popular used in SSL and WEP but no longer considered secure.

Question 19

What is the key size of RC4?

Answer 19

Variable - typically between 40 and 2048 bits. Larger key = better security.

Question 20

What algorithms are block ciphers?

Answer 20

AES, Blowfish, DES, Twofish, 3DES, Serpant

Question 21

What algorithms are stream ciphers?

Answer 21

ChaCha, RC4, A5, Salsa20, Chameleon

Question 22

What does SHA1 stand for?

Answer 22

Secure Hash Algorithm

Question 23

How does SHA1 work?

Answer 23

Takes input and produces hash value known as message digest that is a fixed-size singular and irreversible.

Question 24

What is the hash length of SHA1?

Answer 24

160 bit hash length (20 bytes)

Question 25

What does MD5 stand for?

Answer 25

Message Digest Algorthim

Question 26

How does MD5 work?

Answer 26

Like SHA-1, MD5 processes input data in 512-bit blocks but produces a smaller hash size - Lack security but still used as checksum for data integrity.

Question 27

What is the hash length of MD5?

Answer 27

128 bit (16 byte)

Question 28

What hash begins with $1$?

Answer 28

MD5

Question 29

What hash begins with $2$?

Answer 29

Blowfish

Question 30

What hash begins with $2a$?

Answer 30

Eskblowfish

Question 31

What hash begins with $5$?

Answer 31

SHA-256

Question 32

What hash begins with $6$?

Answer 32

SHA-512

Question 33

What hash begins with $8$?

Answer 33

PBKDF2-SHA256

Question 34

What hash begins with $9$?

Answer 34

scrypt

Question 35

What does HMAC stand for?

Answer 35

Hash-based Message Authentication Code

Question 36

What is HMAC?

Answer 36

Can achieve authentication and verify that data is correct and authentic with shared secret, as opposed to approaches that use signatures and asymmetric cryptography