Cissp - Cryptography

Front 1

Mathematical rules used in encryption and decryption

Back 1

Algorithm or Cipher

Front 2

Hardware or software implementation of cryptography that transforms a message into ciphertext and back to plaintext

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Cryptosystem

Front 3

Instance of 2 different keys generating the same ciphertext from same plaintext

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Key clustering

Front 4

A range of possible values used to construct keys

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Keyspace

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Estimated time, effort or resources necessary to break a cryptosystem

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Work factor

Front 6

Does not require an electronic algorithm and bit alterations, but uses components of physical world - like book, page, line…

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Running key cipher

Front 7

Hiding data in another media type so the existence is concealed. Usually hiding messages in images

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Steganography

Front 8

What is Symmetric Cryptography?

Back 8

Sender and receiver use same key for encryption and decryption
Also called secret keys because each user has to keep the key secret

Front 9

What are some examples of Symmetric Cryptography?

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DES
Triple DES (3DES)
Blowfish
IDEA
RC4, RC5, RC6
AES

Front 10

What is Asymmetric Cryptography?

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AKA Public key
The 2 different keys are mathematically related
One public and one private key

Front 11

What are some examples of Asymmetric Cryptography?

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RSA
ECC
Diffie-Hellman
El Gamel
DSA
Knapsack

Front 12

What security service does Asymmetric Cryptography provide?

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Authentication and nonrepudiation

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What security service does Symmetric Cryptography provide?

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Confidentiality

Front 14

What are block ciphers?

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Message is divided into blocks of bits that are put thru mathematical functions one block at a time
If it is a 64 bit block cipher, your message is broken up into blocks of 64 bits

Front 15

What are stream ciphers?

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Does not break message up into blocks. Treats message as a stream of bits and performs mathematical functions on each bit

Front 16

What is a hybrid encryption method?

Back 16

Symmetric algorithm creates keys used for encrypting bulk data and asymmetric algorithm creates keys for automated key distribution

Front 17

Describe DES
(key type, cipher type, block size, key length)

Back 17

Key type: Symmetric
Cipher type: Block
Block size: 64
Key length:56

Front 18

Describe 3DES
(key type, cipher type, block size, key length)

Back 18

Key type: Symmetric
Cipher type: Block
Block size: 192
Key length:168

Front 19

Describe AES
(key type, cipher type, block size, key length)

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Key type: Symmetric
Cipher type: Rijindael block
Block size: 128
Key length:128, 192, 256

Front 20

What is Spartan Scytale?

Back 20

Strip of papyrus around a wooden rod
Key is a similar sized rod

Front 21

Describe IDEA
(key type, cipher type, block size, key length)

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Key type: Symmetric
Cipher type: Block
Block size: 64
Key length: 128

Front 22

What is the Caesar Cipher?

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Substitution cipher
Shift each letter of alphabet and shift by 3 characters

Front 23

What is Battista cipher disk?

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2 concentric disks
Each disk has alphabet around its periphery
Rotate one disk with respect to the other

Front 24

What are Hebern Machines?

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Rotor based machines
Examples: Japanese Purple, German Enigma, American Sigaba, Stafford

Front 25

What is the Vernam Cipher?

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One time pad
Modulo 26 - wrap around the alphabet

Front 26

Describe RSA
(Key type, use, strength, used in)

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Key type: Asymmetric
Use: Key transport, digital sigs, encryption
Strength: Strong
Used in: smime

Front 27

Describe Diffie Hellman
(Key type, use, strength, used in)

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Key type: Asymmetric
Use: key exchange (agreement)
Strength: Moderate
Used in: SSL handshake

Front 28

Describe El Gamal
(Key type, use, strength, used in)

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Key type: Asymmetric
Use: key exchange, digital signatures, encryption
Strength: very strong
Used in: PKI

Front 29

Describe ECC
(Key type, use, strength, used in)

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Key type: Asymmetric
Use: Key transport, digital sigs, encryption
Strength:
Used in:

Front 30

What is a Message Authentication Code (MAC)?

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Short piece of information used to authenticate a mesage.
Encrypt hash value

Front 31

What is Message Digest 2 (MD2)?

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One way hashing algorithm. Produces a 128 bit hash value. Much slower than MD4 and MD5

Front 32

What is Message Digest 4 (MD4)?

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One way hashing algorithm. Produces 128 bit hash value.

Front 33

What is Message Digest 5 (MD5)?

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One way hashing algorithm. Produces 128 bit hash value. More complex than MD4

Front 34

What is HAVAL?

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One way hash algorithm. Variable length hash value. Modification of MD5 that provides more protection against MD5 vulnerabilities

Front 35

What is SHA?

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One way hash algorithm. Produces 160 bit hash value. Used with DSA

Front 36

Describe digital signatures.

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Hash value that has been encrypted with sender's private key
Hashing ensures integrity
Signing provides authentication and nonrepudiation

Front 37

What security service does encryption provide?

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Confidentiality

Front 38

What security service does hashing provide?

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Integrity

Front 39

What security service does digital signature provide?

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Authentication, nonrepudiation, integrity

Front 40

Describe Public Key Infrastructure (PKI).

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Enables a level of trust with in an environment
ISO authentication framework that uses public key cryptography and X.509 standard
Authentication, confidentiality, nonrepudiation, integrity
Hybrid of symmetric and asymmetric key algorithms

Front 41

Name key components of PKI.

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Certificate Authorities
Certificates
Registration Authority

Front 42

What is an organization or server that maintains and issues digital certificates?

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Certificate Authority

Front 43

What is a mechanism used to associate public keys with collection of components in a manner that is sufficient to uniquely identify the claimed owner?

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Certificate

Front 44

What is the standard for how the CA creates the certificate?

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X.509

Front 45

What performs certification registration duties? Does not issue certificates, but acts as a broker

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Regestration authority

Front 46

What is Link Encryption

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Encrypts all the data along a specific communication path as in a satellite link, T3 line or telephone circuit
User info, header, trailer, addresses, routing data all encrypted
Only data link control messaging info not encrypted
Users do not need to do anything to initiate it since it works at data link and physical layers

Front 47

What is End to End Encryption

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Headers, addresses, routing and trailer info not encrypted
Flexibility for user to decide what gets encrypted and how
Higher granularity of functionality
Each hop computer on network does not need key to decrypt each packet
At application layer

Front 48

What is Multipurpose Internet Mail Extension (MIME)

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Specification that dictates how certain file types should be transmitted and handled
S/Mime or secure MIME is standard for digitally signing email and providing secure data transmission

Front 49

What is Privacy Enhanced Mail (PEM)

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Internet standard for secure email over internet and for in house communication
Authentication, message integrity, encryption and key management
Messages encrypted in AES with CBC mode
Public key management provided by RSA
X.509 standard use for certification structure and format

Front 50

What is Pretty Good Privacy (PGP)?

Back 50

Complete cryptosystem that uses cryptographic protection to protect email and files
Can use RSA public key encryption for key management
IDEA symmetric cipher for bulk encryption of data
Confidentiality using IDEA encryption algorithm
Integrity using MD5 hashing
Authentication using public key certificates
Nonrepudiation using cryptographically signed messages
Uses own type of digital cert - web of trust

Front 51

What are Cipher Only attacks?

Back 51

Attacker has ciphertext of several messages & wants to discover encryption process
Common, but not often successful

Front 52

What are Known Plaintext attacks?

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Attacker has plaintext and ciphertext of one or more message. Trying to discover the key

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What are Chosen Plaintext attacks?

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Attacker has plaintext and ciphertext, but can choose the plaintext that gets encrypted to see the corresponding ciphertext

Front 54

What are Chosen Ciphertext attacks

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Attacker has chosen ciphertext to be decrypted and has access to the decrypted plaintext

Front 55

What is Differential Cryptanalysis?

Back 55

Used first against DES
Attacker takes 2 messages of plaintext and follows the changes that take place to the blocks as they go through the different S-boxes
Compare difference and use results to map probability to different possible key values

Front 56

What is Linear Cryptanalysis?

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Carries out functions to identify the highest probability of a specific key employed during the encryption process using a block algorithm

Front 57

What are Side Channel Attacks?

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Doesn't use mathematics to find the key
Review other facts like how much power consumption was used for encryption, intercept the radiation emissions

Front 58

What are replay attacks?

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Attacker captures some type of data and resubmits it with hopes of fooling the receiving device
Timestamps and sequence numbers are countermeasures

Front 59

What is COCOM (Coordinating Committee for Multilateral Export Controls)?

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Prevent crypto from being exported to dangerous countries

Front 60

What is the Wassenaar Arrangement?

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Symmetric crypto free to export
Asymmetric crypto requires a license
28 countries including US signed it

Front 61

What are US controls on Crypto?

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No controls on import
Signed Wassenaar Agreement but had stricter export controls
Looser export controls occurred on July 2000

Front 62

What is the Electronic Code Book (ECB) mode of DES

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Right block/left block pairing 1-1. Replication occurs. Not enough randomness. Good for small amounts of data. Plain vanilla DES

Front 63

What is the Cipher Block Chaining (CBC) mode of DES

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Blocks of 64 bits with 64 bits initialization vector. Errors will propagate. Adds randomness to DES

Front 64

What is the Cipher feedback mode (CFB) mode of DES

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Stream cipher where the cipher text is used as feedback into key generation. Errors will propagate

Front 65

What is the Output feedback mode (OFB) mode of DES

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Stream cipher that generates the key but XOR-ing the plaintext with a key stream. No errors will propagate

Front 66

What is the Counter Mode (CTR) mode of DES

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Different counter for every block of text