Cryptographic Concepts

Question 1

Digital Signatures

Answer 1

Encrypted Hash of Senders Private Key
supplies, Authentication, Non-repudiation and Integrity

Question 2

Digital Signatures

Answer 2

Encrypted Hash of Senders Private Key
supplies, Authentication, Non-repudiation and Integrity

Question 4

Digital Signatures

Answer 4

Encrypted hash of sender private key

Question 5

DSS

Answer 5

Digital Signature Standard
SHA 2or 3 message softest in conjunction with 3 encryption algorithms; DSA, RSA, ECDSA

Question 6

Salting

Answer 6

Random data used for extra input to a hash. Reduced effectiveness for Rainbow Tables

Question 7

ECC

Answer 7

Elliptic Curve Cryptography

Question 8

Symmetric

Answer 8

Shared secret key,
Poor scalability, easy distribution and non repudiation

Question 9

Asymmetric

Answer 9

Public-Private keys
Scalability, easy distribution

Question 10

Asymmetric Key Use with data

Answer 10

Data:
To encrypt use recipients public key
Decrypt use your own private key
Signature:
Use your private key
Recipient uses public key

Question 11

Symmetric algorithm Use

Answer 11

For bulk encryption eg AES256

Question 12

Asymmetric Algorithm Use

Answer 12

Distribution of symmetric keys
Digital signatures, Non repudiation and key agreement
Eg. RSA, DSS, ECC

Question 13

Hash Use

Answer 13

Digital signatures
Pseudo-Random number generation
Integrity services

Question 14

Post Quantum Cryptography

Answer 14

New kinds of approaches using todays computers but will be resistant to quantum computers when they arrive

Question 15

Quantum Key Distribution

Answer 15

Transferring with photons of light and can’t be copied or intercepted

Question 16

ECB

Answer 16

Electronic Codebook Mode
Block Cipher
Least secure- 64bit blocks with chosen key block repetitions will use same encrypted block

Question 17

CBC

Answer 17

Cipher Block Chaining
Each block is XORed with the block of cipher immediately preceding

Question 18

CTR

Answer 18

Uses an incrementing counter and errors do not propagate

Question 19

Blockchain

Answer 19

Distributed public ledger
Does not use intermediaries
Data chained with a block holding the hash for itself and that of the preceding
To create new, computer solves a puzzle and sends solution to the others participating in the chain

Question 20

Lightweight Cryptography

Answer 20

ECC (asymmetric) for low power devices
AES256 (symmetric) for military

Question 21

PFS

Answer 21

Perfect Forward Secrecy
Don’t use server’s private RSA key
ECDHE to exchange keys and move on
Cannot use the private key to decrypt
More computer power

Question 22

ECDHE

Answer 22

Elliptic Curve Diffie-Hellman Ephemeral
Used for perfect forward secrecy

Question 23

RSA

Answer 23

Rivest, Shamir & Adleman
One of oldest public (asymmetric) key cryptographic algorithms widely used for email and web

Question 24

XOR

Answer 24

Exclusive Or
2 bits identical = 0
2 bits different = 1

Question 25

SRTP

Answer 25

Secure Real Time Transfer Protocol For voice and video Uses AES, HMAC-SHA1

Question 26

NTPsec

Answer 26

Secure Network Time Protocol

Question 27

S/MIME

Answer 27

Secure Multipurpose Internet Mail Connections Public key encryption and signing of content PKI organisation required

Question 28

SSL/TLS

Answer 28

Secure Sockets Layer/ Transports Layer Security Uses HTTPS, with private key on server to transfer symmetric session key.

Question 29

IPsec

Answer 29

Layer 3 authentication and encryption AH (Authentication Header) ESP (encapsulation security payload)

Question 30

FTPS/SFTP

Answer 30

FTPS uses SSL SFTP uses SSH (better) and gives file , directory functionality, interrupt her

Question 31

SASL

Answer 31

Simple Authentication and Security Layer Provides authentication with LDAP, Kerberos, Certificates

Question 32

How to secure DHCP?

Answer 32

In AD DHCP servers must be authorised Switches can be configured with trusted interfaces Distribution only allowed from trusted interfaces Cisco call it DHCP Snooping