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CS 330 Final > Security Part 1 > Flashcards

Security Part 1 Flashcards

1
Q

What does encryption do?

A

renders a message unreadable so anyone seeing it won’t be able to determine the original message

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2
Q

What does decryption do?

A

retrieves the original message

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3
Q

What impacts the strength of an encryption?

A

the number of possible keys

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4
Q

What is the number of possible keys a function of?

A

The length of the key

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5
Q

What is symmetric key encryption?

A

the same key is used to encrypt and decrypt the message and both parties must know the key

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6
Q

What is the key distribution problem?

A

both parties must know the key

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7
Q

What type of encryption does the key distribution problem affect and what is the solution to the problem?

A

Affects symmetric key encryption

Solved by public key encryption

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8
Q

What is brute force search?

A

trying every possible key to find the actual key

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9
Q

What does it mean to be computationally secure?

A

an encryption method is computationally secure if it will take the a very long time to crack the message using the best tech

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10
Q

What is an implication of Moore’s Law in regard to encryption?

A

what is secure today may not be secure years from now

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11
Q

What is a hash function?

A

a computer function that maps input of any size onto an output of a fixed size

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12
Q

What is public key encryption?

A

The use of two keys, a public key, and a private key, that are mathematically related in order to encrypt a message

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13
Q

What does a digital signature do?

A

shows the message came from the sender (not an imposter) and has not been tampered with (has data integrity)

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14
Q

How does a digital signature work (4 characteristics)?

A

uses a hash function to convert the message, m, to a number, ℎ()

each letter is associated with a number and they’re added together mod1000

sender and receiver agree on a hash function

only the sender could encrypt, anyone can decrypt

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15
Q

What are the steps for a digital signature from the sending side?

A
  1. Calculate the hash function, h(m)
  2. Encrypt h(m) with the sender’s private key h(m)_c
  3. Send m and h(m)_c
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16
Q

What are the steps for a digital signature from the receiving side?

A
  1. Receive m and calculate the hash function of m, h(m)

2. Receive and decrypt h(m)_c using the sender’s public key and check to see if it equals h(m)

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17
Q

What do the symbols m, h(m) and h(m)_c signify in encryption?

A

m: plain text
h(m): hash of m
h(m)_c: cypher text

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18
Q

When using a digital signature, how do you know if the message came from the sender and has not been tampered with?

A

The message m came from the sender if when h(m)_c is decrypted, it equals h(m)

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19
Q

How do you find out the sender’s public key in a reliable way?

A

Through a certificate of authority

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20
Q

What do certificates have?

A

The digital signature of a known certificate authority

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21
Q

What is a certificate authority?

A

A small number of trusted organizations

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22
Q

What can your browser verify in regards to secure communication?

A
  • The legitimacy of the digital signature
  • Legitimacy of the certificate
  • The public key of the certificate holder
23
Q

What is HTTPS based on?

A

Using certificate authorities and certificates

24
Q

How do you acquire certificates?

A

A list of them and their public keys are included in a browser

25
Q

What are Secure Hash Algorithms (SHA)?

A

A family of hashing functions

26
Q

What effect does slightly changing the input have on SHA?

A

changes the hash value (the output) considerably

27
Q

What does SHA256 do?

A

Maps any message to a 32 byte (256 bit) number

28
Q

How many different output values are there for SHA256?

A

2^256

29
Q

What are 3 ways people cause security problems?

A
  1. People are careless and make mistakes
  2. People are lazy (i.e. simple passwords)
  3. People can be tricked into divulging confidential information
30
Q

What are the top 3 sources of data breaches?

A
  1. Fraud or scam
  2. Stolen laptop
  3. Document found in trash or unattended
31
Q

What is a trait of all complex pieces of hardware or software?

A

They contain bugs and many points of vulnerability

32
Q

What is wire tapping?

A

Eavesdropping on telephone lines

33
Q

What is sniffing?

A

Eavesdropping on a computer network to obtain propriety information

34
Q

What is radiation?

A

Wires give off an electrical signal that can be easily intercepted without damaging the wires

35
Q

What is web scraping?

A

When a computer program rather than a person surfs the web looking for information

36
Q

What is the estimated global cost of cybercrime?

A

Between $375 billion and $500 billion

37
Q

What is malware?

A

Malicious software, software designed to cause damage to or loss of control of a computer or network

38
Q

What are 9 types of malware?

A
  1. computer virus
  2. worm
  3. torjan horse
  4. phishing
  5. denial of service attack
  6. sniffing
  7. spam
  8. botnet
  9. ransomware
39
Q

What is a computer virus?

A

software that attaches to other programs or

data in order to be executed and can copy itself from file to file

40
Q

What can a computer virus harm?

A 
Data
Program
Machines
The network
Can open a backdoor to hackers
41
Q

What is a worm?

A

Similar to viruses but run on their own (don’t need to attach to other programs)

42
Q

What damage can worms cause?

A

Same as a virus

43
Q

How do worms spread?

A

Using a computer network

44
Q

What is a trojan horse?

A

A software program that appears to be benign, but then does something unexpected behind the scenes

45
Q

What harm can Trojan horses cause?

A

Same as a virus

46
Q

How do trojan horses attack?

A

The user has to launch them

47
Q

What is phishing?

A

an email or text that:

  1. pretends to come from a trusted source
  2. asks for confidential information
48
Q

What is a denial of service attack?

A

many computers overwhelm a website requestion service in attempt to block others from using the website

49
Q

What harm does a denial of service attack cause?

A

Loss of business (no data is lost)

50
Q

What is spam?

A

junk email

51
Q

What is a botnet?

A

A collection of computers that are used together for a common purpose

52
Q

What is ransomware?

A

software that threatens to publish the victim’s files or prevents the victim from accessing their files unless a ransom is paid

53
Q

Why is public/private key encryption so secure?

A

Because when you encrypt with either one, the only way to decrypt is using the other key (other than brute force)

54
Q

What is generally exchanged in public/private key encryption?

A

a shared key or digital signature rather than the whole message

CS 330 Final (6 decks)

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