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Security Plus > Ch10: Understanding Cryptography and PKI > Flashcards

Ch10: Understanding Cryptography and PKI Flashcards

1
Q

Hashing verifies…

A

integrity for data such as email, downloaded files, and files stored on a disk

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2
Q

Two popular hashing algorithms are

A

MD5 and SHA

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3
Q

HMAC verifies…

A

both integrity and authenticity of a message with the use of a shared secret

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4
Q

Protocols such as IPsec and TLS use

A

HMAC-MD5 and HMAC-SHA1

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5
Q

Hashing is a…

A

one-way function that creates a string of characters

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6
Q

Passwords are often stored as…

A

hashes, often salted

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7
Q

Bcrypt and PBKDF2 are…

A

key stretching techniques that help prevent brute force attacks and rainbow table attacks. Both salt the password

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8
Q

MD5, SHA, and HMAC are

A

hashing algorithms (not for encrypting data)

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9
Q

Encryption provides

A

confidentiality and helps ensure that data is viewable only by authorized users (data-at-rest or data-in-transit)

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10
Q

Random numbers are…

A

picked by chance

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11
Q

Pseudo-random numbers

A

appear to be random but are created by deterministic algorithms

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12
Q

In cryptology, confusion indicates…

A

that the ciphertext is significantly different than the plaintext

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13
Q

Diffusion cryptographic techniques ensure

A

small changes in the plaintext result in significant changes in the ciphertext

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14
Q

Stream ciphers

A

encrypt data a single bit or byte at a time in a stream

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15
Q

Block ciphers

A

encrypt data in a specific-sized block

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16
Q

Stream ciphers are more _ than block ciphers when encrypting data in a continuous stream

A

more efficient when encrypting data in a continuous stream

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17
Q

ECB mode is…

A

Electronic Codebook mode is deprecated and should not be used

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18
Q

CBC mode

A

Cipher Block Chaining mode combines each block with the previous block when encrypting data and sometimes suffers from pipeline delays

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19
Q

CTM mode

A

Counter mode combines an IV with a counter to encrypt each block

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20
Q

GCM

A

Galois/Counter mode combines counter mode with hashing techniques for integrity

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21
Q

RADIUS uses what type of encryption?

A

symmetric encryption

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22
Q

AES

A

AES is a strong symmetric block cipher

blocks: 128-bit
keys: 128, 192, 256-bit

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23
Q

DES/3DES

A

block ciphers that encrypt data in 64-bit blocks

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24
Q

3DES was designed as

A

a replacement for DES, but NIST selected AES as the current standard

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25
Is 3DES still used?
Yes, in some applications where legacy hardware doesn't support AES
26
RC4
symmetric stream cipher (most experts recommend using AES instead) keys: 40 to 2048-bit
27
Blowfish
symmetric block cipher blocks: 64-bit keys: 32 to 448-bit
28
Twofish
symmetric block cipher blocks: 128-bit keys: 128, 192, 256-bit
29
NIST standard
AES
30
Which is faster - blowfish or AES-256?
Blowfish is faster
31
DES
symmetric block cipher block size: 64-bit key size: 56-bit
32
3DES
symmetric block cipher blocks: 64-bit keys: 56, 112, 168-bit
33
Symmetric encryption algorithms
AES, DES, 3DES, Blowfish, Twofish, RC4
34
Key element of several asymmetric encryption methods is...
they require a certificate and a PKI
35
Certificates are an important part of...
asymmetric encryption
36
Certificates include
public keys along with details on the owner of the certificate and the CA that issued the certificate
37
Certificate owners share their public key by...
sharing a copy of their certificate
38
RSA is widely used to...
protect data such as email and other data transmitted over the Internet (asymmetric encryption)
39
Diffie-Hellman is a...
secure method of sharing symmetric encryption keys over a public network
40
Elliptic Curve Cryptography is commonly used with...
small wireless devices
41
ECDHE
Elliptic Curve Diffie-Hellman Ephemeral is a version of Diffie-Hellman that uses elliptic curve cryptography to generate encryption keys
42
Steganography
hides messages or other data within a file
43
To detect changes in files that may indicate the use of steganography, use...
hashing
44
For email digital signatures, sign/encrypt with...
sender's private key
45
For email encryption, encrypt with...
recipient's public key
46
For web site encryption, encrypt with...
web site's public key. Symmetric key encrypts data in the web site session
47
A digital signature is
an encrypted hash of a message
48
Digital signatures provide
authentication, non-repudiation, and integrity
49
Both TLS and SSL require...
certificates issued by Certificate Authorities (CAs)
50
Admins should disable....
weak cipher suites and weak protocols on servers
51
When a server has both strong and weak cipher suites, attackers can...
launch downgrade attacks bypassing the strong cipher suite and exploiting the weak cipher suite
52
PKI
A public key infrastructure is a group of technologies used to request, create, manage, store, distribute, and revoke digital certificates
53
You typically request certificates using..
a CSR (certificate signing request)
54
Process of requesting a certificate
Create RSA-based key pair (private first). Include public key in CSR. CA will embed the public key in the certificate (private key is not sent to CA).
55
CAs revoke certificates for several reasons including
when the private key is compromised or the CA is compromised
56
CRL
The certificate revocation list includes a list of revoked certificates and is publicly available
57
Alternative to using a CRL
OCSP (online certificate status protocol) returns answers such as good, revoked, or unknown
58
OCSP stapling
appends a digitally signed OCSP response to a certificate
59
Alternative to OCSP
Certificate stapling, where the certificate presenter appends the certificate with a timestamped digitally signed OCSP response from the CA
60
Public key pinning
web server sends a list of public key hashes that clients can use to validate certificates sent to clients in subsequent sessions
61
Public key pinning helps...
prevent attackers from impersonating a web site with a fraudulent certificate
62
CER
Binary certificate format
63
DER
ASCII certificate format
64
PEM
Most commonly used certificate format Binary or ASCII certificate format Can be used for almost any purpose Can contain server certs, cert chains, keys, CRL
65
P7B
ASCII certificate format used to share the public key | Can contain certs, cert chains, CRL, never the private key
66
P12/PFX
Binary certificate format commonly used to store the private key with a certificate Can contain certs, cert chains, and private keys

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