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SY0-601 > 3.1 Encryption > Flashcards

3.1 Encryption Flashcards

1
Q

What is cryptography?

A

The use of mathematical algorithms to transform information into an encrypted form that is not readable by unauthorized individuals.

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2
Q

What two basic operations do cryptography depend upon?

A

Encryption and decryption.

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3
Q

What does encryption essentially do?

A

Converts information from plaintext into ciphertext.

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4
Q

What does decryption do?

A

Converts ciphertext messages back into their plaintext form.

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5
Q

What do algorithms serve as in cryptography?

A

Mathematical recipes.

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6
Q

What are the two inputs required by encryption algorithms?

What’s the output produced by them?

A

Inputs:

  1. The Plaintext Message (P)
  2. The Encryption Key (K)

Output: The Encrypted Ciphertext (C)

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7
Q

What are the two inputs required by description algorithms?

What’s the output produced by them?

A

Inputs:

  1. The Ciphertext (C)
  2. The Decryption Key (K)

Output: The Plaintext Message (P)

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8
Q

What are the two major categories of encryption algorithms?

A
  1. Symmetric

2. Asymmetric

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9
Q

What’s the key characteristic of symmetric encryption?

A

Encryption and decryption use the same secret key.

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10
Q

What’s the key characteristic of asymmetric encryption?

A

Encryption and decryption use different keys from the same pair.

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11
Q

How many keys do asymmetric cryptography use, and what are they called?

A

2 Keys:
The Public Key – freely distributed to communication partners.
The Private Key – kept secret.

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12
Q

What must the relationship of the keys be in asymmetric cryptography?

A

They must be from the same pair.

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13
Q

How does asymmetric cryptography work?

A

Anything encrypted with one key from a pair can be decrypted with the other key from the same pair.

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14
Q

Which one is faster? Symmetric or asymmetric cryptography?

A

Symmetric cryptography.

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15
Q

What’s more suitable for large organizations, symmetric or asymmetric cryptography?

A

Asymmetric cryptography.

In asymmetric cryptography, each user needs only 2 keys, whereas in symmetric cryptography each user needs a key for each of the other users.

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16
Q

What are the five goals of cryptography?

A
  1. Confidentiality – No unauthorized access.
  2. Integrity – No unauthorized modification.
  3. Authentication – Proof of identity claims.
  4. Obfuscation – Hiding sensitive data.
  5. Non-Repudiation – Verification of origin.
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17
Q

When cryptography is used to protect the confidentiality of information, what are the three states of data that must be considered?

A
  1. Data at Rest
  2. Data in Transit
  3. Data in Use
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18
Q

What is data at rest?

A

Data that is stored on a hard drive or other storage.

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19
Q

What is data in transit?

A

Data that are being transmitted over a network connection.

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20
Q

What is data in use?

A

Data that are being actively processed in memory.

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21
Q

What technology do we use to achieve non-repudiation?

A

Digital signatures.

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22
Q

Which one of the two main categories of cryptography allows for non-repudiation?

A

Asymmetric cryptography.

23
Q

What’s the trade-off involved in choosing a method of encryption?

A

Security Strength vs. Resource Consumption

24
Q

What is code in the context of cryptography?

A

A system that substitutes one word or phrase for another; intended to provide secrecy and/or efficiency.

25
Q

What is a cipher in the context of cryptography?

A

A system that uses mathematical algorithms to encrypt and decrypt messages.

26
Q

What are the two different ways that ciphers process a message called?

A
  1. Stream Ciphers

2. Block Ciphers

27
Q

How do stream ciphers process a message?

A

It operates on one character, or bit, of a message at a time.

28
Q

How do block ciphers process a message?

A

They operate on large segments of the message at the same time.

29
Q

What are the two basic building blocks that ciphers use to perform their encryption and decryption operations?

A
  1. Substitution Ciphers
  2. Transposition Ciphers

These are the building blocks of modern cryptography.

30
Q

What do substitution ciphers do?

A

They change the characters in a message.

31
Q

What are rotation ciphers?

A

They are simple substitution ciphers that shift each letter by an increment.

32
Q

What do transportation ciphers do?

A

They rearrange the characters in a message.

33
Q

What does XOR stand for, and what is it?

A

Exclusive OR

A logical operation that is true when exactly one of the two input values is true.

34
Q

Why does cryptography rely upon pseudorandom number generation?

A

Because we lack a source of truly random numbers.

35
Q

What must we do it achieve “confusion” in cryptography?

A

Every bit of the ciphertext must depend upon more than one bit of the encryption key.

36
Q

What does “diffusion” dictate?

A

It dictates that changing a single bit of the plaintext should change about 50% of the ciphertext bits.

37
Q

What is obfuscation in the context of software development?

A

Using cryptography to hide source code from other users.

38
Q

Should you try to build your own encryption algorithm? Why?

A

No. Not unless you really know what you’re doing.

This is because encryption is really complicated. It uses sophisticated mathematical algorithms, and even the smallest flaw in an algorithm can render that algorithm insecure.

39
Q

What is security through obscurity? Is it a good thing?

A

It means that the security of an algorithm depends upon the secrecy of its approach.

No, it is not a good thing. In fact, if the vendor of an encryption algorithm is using this approach, it’s a big red flag.

40
Q

When your encryption key gets longer, what happens to the security and performance of your encryption?

A

The security goes up while the performance goes down.

41
Q

What kind of encryption algorithm should you choose?

A

One that is well-tested and proven to be secure.

42
Q

What is the One-Time Pad?

A

It’s an unbreakable encryption algorithm where the sender and receiver have identical pads that contain a string of random letters the number of which is at least as long as the total of the characters of all of the messages that the sender and receiver will exchange.

43
Q

What often happens to cryptographic algorithms as they age?

A

They become insecure.

44
Q

What is NIST?

A

The National Institute of Standards and Technology

45
Q

What are the five stages in the cryptographic lifecycle offered by the NIST?

A
  1. Initiation
  2. Development and Acquisition
  3. Implementation and Assessment
  4. Operations and Maintenance
  5. Sunset
46
Q

What happens at the initiation phase of the cryptographic lifecycle?

A

Gather requirements for the new cryptographic system.

47
Q

What happens in the development and acquisition phase of the cryptographic lifecycle?

A

Find an appropriate combination of hardware, software, and algorithms that meet objectives.

48
Q

What happens in the implementation and assessment phase of the cryptographic lifecycle?

A

Configure and test the cryptographic system.

49
Q

What happens in the operations and maintenance phase of the cryptographic lifecycle?

A

Ensure the continued secure operation of the cryptographic system.

50
Q

What happens in the sunset phase of the cryptographic lifecycle?

A

Phase-out the system and destroy/archive keying material.

51
Q

What is the simplest way to take an existing cipher and make it stronger?

A

Increase the length of the encryption key.

52
Q

Alice would like to be able to prove to Charlie that a message she received actually came from Bob. What cryptographic goal is Alice trying to enforce?

A

Non-repudiation.

53
Q

Bob is planning to use a cryptographic cipher that rearranges the characters in a message. What type of cipher is Bob planning to use?

A

Transposition cipher.

54
Q

What operation uses a cryptographic key to convert plaintext into ciphertext?

A

Encryption.

SY0-601 (5 decks)

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