6.0 - Cryptography and PKI

Question 1

What are the Symmetric Algorithms?

Answer 1

• DES (Data Encryption Standard)
• 3DES (Triple Data Encryption Standard)
• IDEA (International Data Encryption Standard)
• AES (Advanced Encryption Standard)
• Blowfish
• Twofish
• RC4
• RC5
• RC6

Question 2

What are the Asymmetric Algorithms?

Answer 2

• Diffie-Hellman
• RSA
• ECC (Elliptic Curve Cryptography)
• DSA (Digital Signature Algorithm)
• PGP (Pretty Good Privacy)
• GPG (Gnu Privacy Guard)

Question 3

Which Algorithms use block ciphers?

Answer 3

• DES (Digital Encryption Standard)
• 3DES (Triple Digital Encryption Standard)
• IDEA (International Data Encryption Algorithm)
• AES (Advanced Encryption Standard)
• Blowfish
• Twofish
• RC5
• RC6

Question 4

Which Algorithms use stream ciphers?

Answer 4

• RC 4

Question 5

ECC Algorithm

Answer 5

• Elliptic Curve Cryptography
• heavily used in mobile devices (tablets, smart phones) because it requires less processing power
• very efficient (6 times more efficient than RSA) and provides better security than an equivalent RSA key of the same size

Question 6

What are the Cipher modes?

Answer 6

• CBC (Cipher Block Chaining)
• GCM (Galois Counter Mode)
• ECB (Electronic Code Book)
• CTR (Counter)
• stream
• block

Question 7

ECB Cipher mode

Answer 7

• electronic code book
• this mode of operation is the simplest cipher mode
• algorithms that use ECB divide the plaintext into blocks and then encrypt each block using the same key
• if any of the plaintext blocks are the same, the resulting ciphertext is the same, making it much easier to crack
• ECB is not recommend for use in an cryptographic protocols today

Question 8

CBC Cipher mode

Answer 8

• cipher block chaining
• is used by some symmetric block ciphers
• because encryption of each block is dependent on the encryption of all previous blocks, CBC sometimes suffers from pipeline delays, making it less efficient than some other modes

Question 9

CTR Cipher mode

Answer 9

• counter mode effectively converts a block cipher into a stream cipher
• combines an IV with a counter to encrypt each block
• multiprocessor systems can encrypt or decrypt multiple blocks at the same time, allowing the algorithm to be quicker on multiprocessor or multi-core systems
• is widely used and respected as a secure mode of operation

Question 10

GCM Cipher mode

Answer 10

• galois-counter mode
• combines counter mode with hashing techniques for integrity
• provides data authenticity (integrity) and confidentiality
• encrypts the data for confidentiality and includes hashing techniques for integrity

Question 11

What are the hashing algorithms?

Answer 11

• MD5 (Message Digest 5)
• SHA (Secure Hashing Algorithm)
• HMAC (Hashed Message Authentication Code)
• RIPEMD (RACE Integrity Primitives Evaluation Message Digest)

Question 12

What are the key stretching algorithms?

Answer 12

• BCRYPT

- PBKDF2 (Password-based Key Derivation Function 2)

Question 13

Diffie-Hellman Algorithm

Answer 13

• susceptible to man-in-the-middle so you need to use some form of authentication such as a password or digital certificate at the beginning of the exchange process
• used for key exchange inside of creating a VPN tunnel establishment as part of IPSec

Question 14

Symmetric Encryption

Answer 14

• symmetric algorithms or private key uses the same key to encrypt and decrypt data
• when transmitting encrypted data, symmetric encryption algorithms use the same key to encrypt and decrypt data at both ends of the transmission media