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CEH > Chapter 12 - Cryptography > Flashcards

Chapter 12 - Cryptography Flashcards

1
Q

Cryptography

A

Science or study of protecting information whether in transit or at rest.

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2
Q

Cryptanalysis

A

Study and methods used to crack cipher text

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3
Q

Linear Cryptanalysis

A

Works best on block ciphers

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4
Q

Differential Cryptanalysis

A

Applies to symmetric key algorithms. Compares differences in the inputs to how each one affects the outcome.

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5
Q

Integral Cryptanalysis

A

Input vs Output comparison same as differential; however, runs multiple computations of the same block size input.

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6
Q

Nonrepudiation

A

Means by which a recipient can ensure the identity of the sender and neither party can deny sending

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7
Q

What are the 2 general forms of cryptography?

A

Substitution - bits are replaced by other bits. Transposition - Doesn’t

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8
Q

Stream Cipher

A

Readable bits are encrypted one at a time in a continuous sream. Usually done by an XOR operation.

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9
Q

Block Cipher

A

Data bits are split up into blocks and fed into the cipher

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10
Q

XOR

A

Exclusive OR; If inputs are the same (0,0 or 1,1), function returns 0; if inputs are not the same (0,1 or 1,0), function returns 1 . Key chosen for cipher must have a length larger than the data; if not, it is vulnerable to frequency attacks.

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11
Q

Symmetric Encryption

A

Known as a single key or shared key. One key is used to encrypt and decrypt the data. Suitable for LARGE amounts of data. Problems are key distribution and management

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12
Q

Algorithm - DES

A

Symmetric Encryption - Block cipher; 56 bit key; quickly outdated and now considered not very secure.

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13
Q

Algorithm - 3DES

A

Symmetric Encryption - Block cipher; 168 bit key; more effective than DES but much slower.

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14
Q

Algorithm - AES

A

Symmetric Encryption - Advanced Encryption Standard - Block cipher; 128, 192, or 256 bit key; repalces DES; much faster than DES and 3DES

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15
Q

Algorithm - IDEA

A

Symmetric Encryption - International Data Encryption Algorithm - block cipher; 128 bit key; originally used in PGP 2.0

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16
Q

Algorithm - Twofish

A

Symmetric Encryption - Block cipher; up to 256 bit key.

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17
Q

Algorithm - Blowfish

A

Symetric Encryption - Fast block cipher; replaced by AES; 64 bit block size; 32 to 448 bit key: considered public domain.

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18
Q

Algorithm - RC (Rivest Cipher)

A

Symmetric Encryption - RC2 to RC6; block cipher; comparable key length up to 2040 bits; RC6 (latest) uses 128 bit blocks and 4 bit working registers; RC5 uses varaible block sizes and 2 bit working registers. RC4 is stream cipher.

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19
Q

Asymmetric Encryption

A

Uses two types of keys for encryption and decryption ( public and private key)

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20
Q

Public vs Private key

A

Public key generally used for encryption; can be sent to anyone. Private keys are kept secret; used for decryption

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21
Q

Algorithm - Diffie-Hellman

A

Asymmetric - Developed as a key exchange protocol; used in SSL and IPSec; if digital signatures are waived, vulnerabl to MITM attacks.

22
Q

Algorithm - Elliptic Curve Cryptosystem (ECC)

A

Asymmetric - Uses points on elliptical curve along with logarithmic problems; uses less processing power; good for mobile devices.

23
Q

Algorithm - El Gamal

A

Asymmetric - Not based on prime number factoring; uses solving of discrete logarithm problems.

24
Q

Algorithm - RSA

A

Asymmetric - Achieves strong encryption through the use of two large prime numbers; factoring these create key sizes up to 4096 bits; moder de facto standard.

25
Q

Hash

A

One-way mathematical function that produces a fix-length string (hash) based on the arrangements of data bits in the input.

26
Q

MD5

A

Hash - Message digest algorithm) - Produces 128 bit hash expressed as 32 digit hexadecimal number; has flaws ; still used

27
Q

SHA-1

A

Hash - Developed by NSA; 160 bit value output

28
Q

SHA-2

A

Hash - Four separate hash functions; produce outputs of 224, 256, 384 and 512 bits; not widely used.

29
Q

SHA-3

A

Hash - Uses sponge construction (random permutations)

30
Q

RIPEMD-#

A

Hash - Works through 80 stages; executing 5 blocks 16 times each; uses modulo 32 addition . The # indicates bit length.

31
Q

Collision

A

Occurs when two or more files create the same output

32
Q

DUHK Attack

A

Don’t use hard coded Keys - Allows attackers to access keys in certain VPN implementation; affects devices using ANSI X.931 with a hard-coded seed key.

33
Q

Rainbow Tables

A

Contain precomputed hashes to try and find out passwords

34
Q

Salt

A

adds random characters bits to increase hash complexity

35
Q

HashCalc

A

Hash tool

36
Q

MD5 Calculator

A

Hash Tool

37
Q

HashMyFiles

A

Hash Tool

38
Q

Steganography

A

Practice of concealing a messag inside another medium so that only the sender and recipient know of its existence.

39
Q

Ways to Identify Steganography

A

Text, images, audio and video

40
Q

Steganography Methods

A

Least significant bit insertion - changes least meaningful bit. Masking and Filtering (grayscale images) - like watermarking . Algorithmic Transformation - hides in mathematical functions used in image compression.

41
Q

QuickStego

A

Steganography tool

42
Q

gifshuffle

A

Steganography tool

43
Q

SNOW

A

Steganography tool

44
Q

Steganography Studio

A

Steganography tool

45
Q

OpenStego

A

Steganography tool

46
Q

Public Key Infrastructure (PKI)

A

Structure desinged to verify and authenticate the identity of individuals.

47
Q

Registration Authority

A

Verifies user identity

48
Q

Certificate Authority

A

Third party to the organization; creates and issues digital certificates

49
Q

Certificate Revocation List (CRL)

A

Used to track which certificates have problems and which have been revoked.

50
Q

Validation Authority

A

Used to validate certificates via Online Certificate Status Protocol (OCSP)

51
Q

Trust Model

A

How entities within an enterprise deal with keys, signatures and certificates

52
Q

Cross-Certification

A

Allows a CA to trust another CS in a completely different PKI; allows both Cas to validate certificates from either side.

CEH (13 decks)

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