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Cyber Security > Cryptography (CRY) > Flashcards

Cryptography (CRY) Flashcards

1
Q

Algorithm

A

mathematical function that determines the cryptographic operations

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2
Q

Asymmetric

A

encryption system using a pair of mathematically related unequal keys

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3
Q

Asymmetric Cryptography

A

Sender and receiver have public and private keys.
Public to encrypt a message, private to decrypt
Slower than symmetric, secret key (100 to 1000)

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4
Q

Asynchronous

A

encrypt/decrypt request are processed in queues.

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5
Q

Birthday attack

A

statistical probabilities of a collision are more likely than one thinks

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6
Q

Black Boxing

A

manipulates toll-free line voltage to phone for free

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7
Q

Block Cipher

A

Segregating plaintext into blocks and applying identical encryption algorithm and key

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8
Q

Blowfish

A

By Bruce Schneider key lengths 32 to 448 bits, used on Linux systems that use bcrypt (DES alternative)
Confidentiality Symmetric, Algorithm

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9
Q

Blue Boxing

A

tone simulation that mimics telephone co. system and allows long distance call authorization

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10
Q

Brute Force

A

with enough computing power trying all possible combinations

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11
Q

Caesar cipher

A

mono-alphabetic substitution cipher

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12
Q

CBC Cipher Block Chaining

A

blocks of 64 bits with 64bits initialization vector. Errors will propagate

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13
Q

Certificate Authority

A

PKI, entity trusted by one or more users as an authority in a network that issues, revokes, and manages digital certificates.

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14
Q

Certificate revocation list (CRL)

A

a temporary public file to inform others of a compromised digital certificate

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15
Q

Certification authority

A

a trusted issuer of digital certificates

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16
Q

CFB

A

Cipher Feedback: stream cipher where the cipher text is used as feedback into key generation. errors will propagate

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17
Q

Checksum

A

a mathematical tool for verifying no unintentional changes have been made

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18
Q

Cipher

A

cryptographically transformation that operates on characters or bits. DES, word scramble, shift letters

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19
Q

Cipher text

A

scrambled form of the message or data

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20
Q

Clustering

A

situation wherein plain text messages generates identical cipher text messages using the same algorithm but with different crypto-variables or keys

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21
Q

Code

A

substitution at the word or phrase level

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22
Q

Codes

A

cryptographic transformation that operates at the level of words or phrases. Example: “wedding” means “attack”

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23
Q

Collisions

A

outputs within a given function are the same result

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24
Q

Concatenation

A

joining two pieces of text -

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25
Q

Confidentiality Asymmetric Algorithms

A

RSA (Rivest, Shamir, Adelman) - Factoring large primes
Elliptic Curve Cryptosystem - Logs, discrete logs
Diffie-Hellman for key exchange
El Gamal

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26
Q

Confidentiality Asymmetric Strengths

A

Confidentiality
Authentication
Non-repudiation
Key management easier
Access control
Integrity

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27
Q

Confidentiality Asymmetric Weaknesses

A

More processor-intensive than symmetric encryption
Still need to protect private key

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28
Q

Confidentiality Symmetric Algorithms

A

AES (Extended AES, Rijndael)
RC4
DES - Brute force can break it, but not flawed. Types Lucifer, Feistle Cipher, Triple DES.

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29
Q

Confidentiality Symmetric Strengths

A

Confidentiality protection
Speed
Bulk encryption - large files efficiency
Availability of free algorithms

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30
Q

Confidentiality Symmetric Weaknesses

A

Key management
Scalability issues
Shared keys - No authentication or non-repudiation, Forgery by receiver is possible

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31
Q

Confusion

A

mixing the key values during repeated rounds of encryption, make the relationship between ciphertext and key as complex as possible

relationship between the plaintext and the key is so complicated that an attacker can’t merely continue altering the plaintext and analyzing the resulting ciphertext to determine the key

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32
Q

Cross certification

A

two certificate authorities that trust each other

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33
Q

Cryptanalysis

A

code breaking, practice of defeating the protective properties of cryptography.

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34
Q

Cryptographic Algorithm

A

Step by step procedure to encipher plaintext and decipher cipher text

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35
Q

Cryptography

A

code making

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36
Q

Cryptography Goals

A

Confidentiality
Integrity
Proof of origin
Non-repudiation
Protect data at rest
Protect data in transit

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37
Q

Cryptology

A

The study of cryptography and cryptanalysis
We think about Confidentiality, Integrity, and key exchange

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38
Q

Cryptology - CRY

A

cryptography + cryptanalysis

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39
Q

Cryptology implementation

A

IPSec
TLS

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40
Q

Cryptosystem

A

set of transformations from a message space to cipher space

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41
Q

Cryptovariable

A

key

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42
Q

CTR

A

Counter: secure long messages

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43
Q

Decipher

A

descrambling the encrypted message with the corresponding key

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44
Q

Dictionary attack

A

try a list of words in passwords or encryption keys

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45
Q

Diffie Hellman Key exchange

A

switching secret keys over an insecure medium without exposing the keys
Not encryption
Technically - Large prime generation, Groups

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46
Q

Diffusion

A

mix location of plaintext throughout ciphertext, change of a single bit should drastically change hash, dissipate pattern

a change in the plaintext results in multiple changes spread throughout the ciphertext

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47
Q

Digital certificate

A

a electronic attestation of identity by a certificate authority

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48
Q

Digital Signature

A

Asymmetric encryption of a hash of message

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49
Q

DSA

A

Digital Signature Algorithm – the US Government
Equivalent of the RSA algorithm

50
Q

Dumpster Diving

A

going through someone’s trash to find useful or confidential info –it is legal but unethical in nature

51
Q

ECB

A

Electronic Code Book - right block/left block pairing 1-1. Replication occurs. Secure short messages.
One of the Block modes of symmetric ciphers

52
Q

ECC

A

Elliptic Curve Cryptosystem: mathematical properties of elliptical curves, IT REQUIRES FEWER RESOURCES THAN RSA. Used in low power systems (mobile phones etc.)

53
Q

el Gamal

A

Works with discrete logarithms, based on
Diffie Hellman

54
Q

Encipher

A

act of scrambling the cleartext message by using a key.

55
Q

End-to-end encryption

A

Encrypted information that is sent from point of origin to destination. In symmetric encryption this means both having the same identical key for the session

56
Q

Ephemeral keys

A

cryptographic keys that are generated for each execution of a key establishment process. SYN-Session Key

57
Q

Exclusive OR

A

Boolean operation that performs binary addition

58
Q

Hash function

A

one way encryption, for integrity purposes

59
Q

Hybrid Cryptography

A

z-Uses both asymmetrical and symmetrical encryption:
asymmetrical for key exchange
symmetrical for the bulk - thus it is fast
example: SSL, PGP, IPSEC S/MIME

60
Q

IDEA

A

International Data Encryption Algorithm
64 bit plaintext and 128 key length with confusion and diffusion used in PGP software patented requires licenses fees/free noncom.

61
Q

Information Theory

A

Claude Elmwood Shannon

62
Q

Integrity - How do we know about change?

A

Hash functions
Checksums - Accidental
Message Authentication Code

63
Q

Initialization Vector

A

randomly-generated value used by many cryptosystems to ensure that a unique ciphertext is generated

64
Q

Kerckhoff’s principle

A

only the key protects the encrypted information

65
Q

Key clustering

A

two different keys decrypt the same cipher text

66
Q

Key escrow

A

for PKI, to store another copy of a key

67
Q

Key Length

A

use with each algorithm based on the sensitivity of information transmitted, longer key the better!

68
Q

Key management

A

creation distribution update and deletion

69
Q

Key or Crypto variable

A

Information or sequence that controls the enciphering and deciphering of messages

70
Q

Key space

A

total number of keys available that may be selected by the user of a cryptosystem

71
Q

Keyed-Hashing for Message Authentication

A

a hash that has been further encrypted with a symmetric algorithm

72
Q

Link encryption

A

stacked encryption using different keys to encrypt each time

73
Q

Man-in-the-middle attack

A

adversary intercepts encrypted communications, decrypts, views, encrypts, and send along to the true destination

74
Q

Message Authentication Code

A

Integrity intentional changes

75
Q

Message digest

A

summary of a communication for the purpose of integrity

76
Q

Message digest size for hash functions

A

Hash of Variable Length
HAVAL 128, 160, 192, 224, 256 bits

Hash message authentication code
HMAC Variable

Message Digest
MD5 128 bits

Secure Hash Algorithm
SHA-1 160 bits

SHA2-224/SHA3-224
SHA2-256/SHA3-256
SHA2-384/SHA3-384
SHA2-512/SHA3-512

RIPE Message Digest
RIPEMD-128
RIPEMD-160
RIPEMD-256 (security equivalent to 128)
RIPEMD-320 (security equivalent to 160)

77
Q

Moore’s Law

A

computing power will double every 18 months

78
Q

multi-party control

A

for PKI, to have more than one person in charge of a sensitive function

79
Q

Non-repudiation

A

impossibility of denying authenticity and identity

80
Q

Null Cipher

A

used in cases where the use of encryption is not necessary but yet the fact that no encryption is needed must be configured in order for the system to work. Ex. Testing, stenography

81
Q

OFB

A

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

82
Q

One time pad

A

a running key using a random key that is never used again

Use a different substitution alphabet for each letter of the plaintext message.

AKA: Vernam cipher

83
Q

Permutation /transposition

A

Moving letters around

84
Q

PGP

A

GPG; encrypt attached files

85
Q

Phreakers

A

hackers who commit crimes against phone companies

86
Q

Plain text

A

natural or human-readable form of message

87
Q

Plaintext

A

message in clear text readable form

88
Q

Polyalphabetic

A

using many alphabets

89
Q

Public Key Infrastructure (PKI)

A

collection of business processes and technologies used for binding individuals to a digital certificate

90
Q

Rainbow Tables

A

a list of hash values, presorted to speed lookup. typically for cracking password hashes. It is a form of time-memory tradeoff, using less CPU at the cost of more storage. A control to reduce this type of attack is salting.

91
Q

RC5

A

Variable algorithm up 0 to 2048 bits key size

92
Q

Red boxing

A

Pay phones cracking

93
Q

Registration Authority

A

performs certificate registration services on behalf of a CA. RA verifies user credentials

94
Q

Revocation

A

for PKI, decertify an entities certificate

95
Q

Rijndael Block Cipher Algorithm

A

for speed, simplicity and resistance against known attacks. Variable block length and variable key lengths (128,192 and 256 bits)

96
Q

Rivest Cipher 5

A

RC5: symmetric algorithm patented by Rivest, Shamir, and Adleman (RSA) Data Security, the people who developed the RSA asymmetric algorithm. RC5 is a block cipher of variable block sizes (32, 64, or 128 bits) that uses key sizes between 0 (zero) length and 2,040 bits.

97
Q

RSA

A

Rivest, Shamir, & Adleman: works with one way math with large prime numbers (aka trap door
functions). Can be used for encryption, key exchange
and digital signatures)

98
Q

Running key

A

an encryption method that has a key as long as the message

99
Q

Script kiddie

A

Someone with moderate hacking skills, gets code from the Internet.

100
Q

Shift cipher (Caesar)

A

moving the alphabet intact a certain number spaces

101
Q

Side channel attack

A

inference about encrypted communications

102
Q

SP-network

A

process described by Claude Shannon used in most block ciphers to increase their strength

103
Q

Steganography

A

hiding the fact that communication has occurred

104
Q

Stream cipher

A

operate on one character or bit of a message (or data stream0 at a time.

Examples: Caesar cipher, one-time pad

105
Q

Substitution

A

trading one for another

use the encryption algorithm to replace each character or bit of the plaintext message with a different character

106
Q

Symmetric

A

encryption system using shared key/private key/single key/secret key

107
Q

Symmetric Cryptography

A

Both the receiver and the sender share a common secret key. Larger key size is safer > 128
Can be time-stamped (to counter replay attacks)
Does not provide mechanisms for authentication and non-repudiation

108
Q

Symmetric encryption memorization chart

A

Advanced Encryption Standard (AES), block size 128, key size 128, 192, 256

Rijndael, block size Variable, key size 128, 192, 256

Blowfish (often used in SSH), block size 64, key size 32-448

Data Encryption Standard (DES), block size 64, key size 56

IDEA (used in PGP), block size 64, key size 128

Rivest Cipher 4 (RC4), block size N/A (stream cipher), key size 40-2048

Rivest Cipher 5 (RC5), block size 32, 64, 128, key size 0-2040

Rivest Cipher 6 (RC6), block size 128, key size 128, 192, 256

Skipjack, block size 64, key size 80

Triple DES (3DES), block size 64, key size 112 or 168

CAST-128, block size 64, key size 40-128

CAST-256, block size 128, key size 128, 160, 192, 224, 256

Twofish, block size 128, key size 1-256

109
Q

Synchronous

A

each encryption or decryption request is performed immediately

110
Q

Transposition/permutation

A

process of reordering plaintext to hide the message rambo = ombar

111
Q

Two fish

A

Key lengths 256 bits blocks of 128 in 16rounds BEAT OUT BY Rijndal for AES, based on Blowfish

112
Q

Vernam

A

cipher (one time pad): key of a random set of non-
repeating characters

113
Q

Vigenere

A

polyalphabetic substitution

114
Q

Watermarking

A

intellectual property management technique for identifying after distribution

115
Q

White box

A

dual tone, multifrequency generator to control phone system

116
Q

Work factor

A

effort/time needed to overcome a protective measure

117
Q

If you want to encrypt a confidential message

A

Use the recipient’s public key

118
Q

If you want to decrypt a confidential message sent to you

A

Use your private key

119
Q

If you want to digitally sign a message you are sending to someone else

A

Use your private key

120
Q

If you want to verify the signature on a message sent by someone else

A

Use the sender’s public key

Cyber Security (19 decks)

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