Flashcards in Chapter 8 - Cryptography Deck (44)

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1

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what is cryptography?

8 - 245

### the study of cryptographic algorithms

2

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what is a cipher?

8 - 245

### a method used to encode characters to hide their value

3

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2 methods of ciphering (nonmathematical)

8 - 246

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substitution (shift the letters over) and

transposition (break the letters into separate blocks and then scramble the blocks)

4

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how do you do ROT13?

8 - 247

### shift the letter by 13. works backwards and forwards.

5

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what was the enigma typewriter?

8 - 248

### typewriter that implemented a multi-alphabet substitution cipher

6

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what is steganography?

8 - 248

### process of hiding a message in a medium like a digital image, audio file, or other file

7

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what is the most common method of steganography?

8 - 248

### least significant bit method

8

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3 major areas of modern cryptography

8 - 249

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symmetric - same key at each end, which will be a secret (private) key

asymmetric

hashing algorithms

9

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what are the two kinds of ciphers that symmetric methods use?

8 - 250

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block cipher

steam cipher

10

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9 examples that use symmetric algorithms

8 - 250

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Data Encryption Standard - replaced by AES, uses 56 bit key

Triple-DES - more secure than DES, uses 3 56 bit keys

Advanced Encryption Standard - uses the Rijndael algorithm, key sizes are 128, 192, 256

AES256 - US Govt Top Secret, 256 bit

CAST - Carlisle Adams and Stafford Tavares

Ron's Cipher - RC4, RC5, and RC6. max key size 2048.

Blowfish and Twofish - symmetric block cipher, variable length keys, 64 bit block cipher

International Data Encryption Algorithm - Swiss developed, 128 bit

One-Time Pads - the only truly secure cryptographic implementations, uses a key that is as long as a plaintext message

11

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two kinds of key exchange

8 - 251

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in-band

and

out-band

12

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what is a common approach to achieving forward secrecy

8 - 251

### use ephemeral keys

13

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you are exchanging keys over an insecure medium and IPSec is not part of the scenario. what algorithm will you be using?

8 - 253

### Diffie-Hellman

14

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this cryptography is similar to RSA but uses smaller key and is based on the idea of using points on a curve

8 - 253

### Elliptic Curve Cryptography

15

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a hashing algorithm is different from cryptography because it has these 3 characteristics

8 - 255

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it must be one-way

variable length input produces fixed length output

the algorithm must have few or no collisions

16

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when you are key stretching, how do you usually make it stronger?

tell me 2 types of key stretching

8 - 256

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make it longer

Password-Based Key Derivation Function 2 - applies a hash or HMAC to the password/passphrase along with salt to produce a derived key

Bcrypt - used with passwords, essentially uses a derivation of the Blowfish algorithm, converted to a hashing algorithm, to hash a password and add Salt to it

17

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common code breaking techniques. tell me 5

8 - 257

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frequency analysis - looking at blocks to determine patterns

chosen plaintext - obtain the ciphertexts corresponding to a set of plaintexts of their own choosing

related key attack - like a chosen plaintext attack, except the attacker can obtain ciphertexts encrypted under two different keys

brute force attacks - apply every possible combination of characters

exploiting human error - not encrypting when you should

18

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what does WPA use? what does WPA2 use?

8 - 258

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TKIP

CCMP

19

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the three most important concepts in security

8 - 259

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confidentiality

integrity

availability

20

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what are the two things that HMAC uses?

8 - 260

### hashing algorithm and a symmetric key

21

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what's a digital signature?

8 - 261

### validates the integrity of the message and the sender

22

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what is nonrepudiation responsible for?

8 - 262

### prevents one party from denying actions they carried out

23

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tell me the 4 main trust models of PKI

8 - 262

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bridge - peer to peer relationship between the root CAs

hierarchal - root CA at top provides all the info

hybrid - two root CAs, but the peer to peer occurs between the intermediate CAs

mesh - expands the bridge, more than 2

24

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what does X.509 define?

8 - 267

### defines the certificate formats and fields for public keys

25

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who developed Secure Electronic Transaction?

8 - 270

### visa and mastercard

26

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tell me what Kerckhoff's principle is.

8 - 254

### states that the security of an algorithm should depend only on the secrecy of the key and not on the secrecy of the algorithm itself

27

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this is the most widely used and recommended hashing algorithm

8 - 255

### SHA2

28

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the strength of a cryptographic system is determined by what?

what is strength also known as?

8 - 257

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how difficult it is to crack

work factor

29

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in terms of THIS chapter, what does MAC stand for and what is it derived from?

8 - 260

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message authentication code

the message and the shared key

30