Topic 4 Reset Flashcards
(60 cards)
1
Q
The process of making and using codes to secure the transmission of information
A
Cryptography
2
Q
“Kryptosâ€
A
Cryptology
Comes from the greek word meaning hidden
3
Q
“Graphein”
A
Comes from the greek word meaning write
4
Q
Code breaking
A
Basic Terms
Cryptanalysis
5
Q
The process of obtaining the original message from the encrypted message
A
Cryptanalysis
6
Q
Code designing
A
Basic Terms
Cryptography
7
Q
can be used to check the integrity of a message: that the message has not been changed
A
Digest
8
Q
The secret key is shared between two parties
A
Private key cryptosystems/ciphers
9
Q
The secret key is not shared and two parties can still communicate using their public keys
A
Public key cryptosystems/ciphers
10
Q
1 key (private key)
A
Symmetric cipher
11
Q
2 keys (public and private key)
A
Asymmetric cipher
12
Q
- Is a substitution cipher, named after Julius Caesar
- Key = 3
- Replaces each letter by the 3rd letter
A
Caesar Cipher
13
Q
Each letter is translated into the letter a fixed number of positions after it in the alphabet table
A
Caesar Cipher Operation principle:
14
Q
replaces one symbol with another
A
Substitution cipher
15
Q
- A message in its natural format readable by an attacker
- Original message or data (also called cleartext
A
Plaintext
16
Q
Message altered to be unreadable by anyone except the intended recipients
A
Ciphertext
17
Q
Transforming the plaintext under the control of the key
A
Encryption
18
Q
Sequence that controls the operation and behavior of the cryptographic algorithm
A
Key
19
Q
Transforming the ciphertext back to the original plaintext
A
Decryption
20
Q
- Encrypts one fixed length group of bits at a time - SIZE is predetermined
- The block size is a fixed size - 64, 128, 256, 512, bit blocks
- Require padding to short blocks before encryption
- Used for symmetric encryption not asymmetric
A
Block Cipher
21
Q
- Are fast and easy to implement in hardware
- Encryption is performed 1 bit or 1 byte at a time
- Mixes plaintext with key stream
- Either using Symmetric Key or Public Key
- The starting state should never be the same twice — uses initialization vector
A
Stream Ciphers
22
Q
- Are stronger but slower and often implemented in hardware
- One or large block at a time
- Substitution and transposition
A
Block Ciphers
23
Q
- Stream Ciphers
- Block Ciphers
A
Types of Cryptography
24
Q
- Electronic Codebook (ECB)
- Cipher Block Chaining (CBC)
- Counter (CTR)
A
Block Cipher Mode Operations
25
1. Key to ciphertext relationship is very complicated
2. Key cannot be determined on the ciphertext
Confusion
26
1. The simplest encryption mode
2. Each block is encrypted with the same key—identical plaintext block created identical cipher block
Electronic Codebook (ECB)
27
1. Easy to implement
2. Each plaintext block is XORed with the previous ciphertext block
3. Adds additional randomization
4. Uses initialization vector for the first block
Cipher Block Chaining (CBC)
28
1. Block cipher mode - acts like a stream cipher
2. Encrypts using the values of the counter - 0, 1, 2 etc
3. Plaintext can be any size - XOR 8 bits at a time instead of 128 bit block
Counter (CTR)
29
# Cryptology
Comes from the greek word meaning hidden
“Kryptosâ€
30
# What is Cryptography
Includes:
1. Techniques for making sure that encrypted messages are not modified en route
2. Techniques for secure identification/authentication of communication partners
31
# What is Cryptography
Refers to:
1. The practice and study of encryption
2. Transforming information in order to prevent unauthorized people from reading it
32
Cryptanalysis
The process of obtaining the original message from the encrypted message
33
Comes from the greek word meaning write
"Graphein"
34
Cryptography
The process of making and using codes to secure the transmission of information
35
1. Output should be different from the input
2. Change 1 bit of the input, at least 50% of the output should change
Diffusion
36
# Basic Terms
Cryptography
Code designing
37
# Basic Terms
Cryptanalysis
Code breaking
38
Digest
can be used to check the integrity of a message: that the message has not been changed
39
Private key cryptosystems/ciphers
The secret key is shared between two parties
40
Public key cryptosystems/ciphers
The secret key is not shared and two parties can still communicate using their public keys
41
Symmetric cipher
1 key (private key)
42
Asymmetric cipher
2 keys (public and private key)
43
Caesar Cipher
* Is a substitution cipher, named after Julius Caesar
* Key = 3
* Replaces each letter by the 3rd letter
44
Caesar Cipher Operation principle:
Each letter is translated into the letter a fixed number of positions after it in the alphabet table
45
Substitution cipher
replaces one symbol with another
46
Plaintext
* A message in its natural format readable by an attacker
* Original message or data (also called cleartext
47
Ciphertext
Message altered to be unreadable by anyone except the intended recipients
48
Encryption
Transforming the plaintext under the control of the key
49
Key
Sequence that controls the operation and behavior of the cryptographic algorithm
50
Decryption
Transforming the ciphertext back to the original plaintext
51
Types of Cryptography
1. Stream Ciphers
2. Block Ciphers
52
Stream Ciphers
1. Are fast and easy to implement in hardware
2. Encryption is performed 1 bit or 1 byte at a time
3. Mixes plaintext with key stream
4. Either using Symmetric Key or Public Key
5. The starting state should never be the same twice — uses initialization vector
53
Block Ciphers
1. Are stronger but slower and often implemented in hardware
2. One or large block at a time
3. Substitution and transposition
54
What is a Block Cipher?
1. Encrypts one fixed length group of bits at a time - SIZE is predetermined
2. The block size is a fixed size - 64, 128, 256, 512, bit blocks
3. Require padding to short blocks before encryption
4. Used for symmetric encryption not asymmetric
55
Confusion
1. Key to ciphertext relationship is very complicated
2. Key cannot be determined on the ciphertext
56
Diffusion
1. Output should be different from the input
2. Change 1 bit of the input, at least 50% of the output should change
57
Block Cipher Mode Operations
1. Electronic Codebook (ECB)
2. Cipher Block Chaining (CBC)
3. Counter (CTR)
58
Electronic Codebook (ECB)
1. The simplest encryption mode
2. Each block is encrypted with the same key—identical plaintext block created identical cipher block
59
Cipher Block Chaining (CBC)
1. Easy to implement
2. Each plaintext is block is XORed with the previous ciphertext block
3. Adds additional randomization
4. Uses initialization vector for the first block
60
Counter (CTR)
1. Block cipher mode - acts like a stream cipher
2. Encrypts using the values of the counter - 0, 1, 2 etc
3. Plaintext can be any size - XOR 8 bits at a time instead of 128 bit block
