Stream Ciphers and Block Ciphers

Question 1

Encryption is done one bit or byte at a time
– High speed, low hardware complexity
* Used with symmetric encryption
– Not commonly used with asymmetric encryption
* The starting state should never be the same twice
– Key is often combined with an initialization vector (IV)

Answer 1

Stream Ciphers

Question 2

Encrypt fixed-length groups
– Often 64-bit or 128-bit blocks
– Pad added to short blocks
– Each block is encrypted or decrypted independently
* Symmetric encryption
– Similar to stream ciphers
* Block cipher modes of operation
– Avoid patterns in the encryption
– Many different modes to choose from

Answer 2

Block Ciphers

Question 3

Encrypt one fixed-length group of bits at a time
– A block
* Mode of operation
– Defines the method of encryption
– May provide a method of authentication
* The block size is a fixed size
– Not all data matches the block size perfectly
– Split your plaintext into smaller blocks
– Some modes require padding before encrypting

Answer 3

Cipher Block Mode of Operation

Question 4

Blank verifies integrity for data such as email, downloaded files, and files stored on a disk. A blank is a number created with a hashing algorithm.

Answer 4

Hash

Question 5

A number derived from performing a calculation on data such as a message, patch, or file. This creates a fixed length stream of bits or hexadecimal characters, which cannot be reversed to recreate the original data.

Answer 5

Hash

Question 6

Is SHA 0 used?

Answer 6

No

Question 7

Blank are a group of hashing algorithms with variations in grouped four families-SHA-0, SHA-1, SHA-2, and SHA-3

Answer 7

Secure Hash Algorithms

Question 8

Blank is an updated version that creates 160-bit hashes. It is similar to the MD5 algorithm. Weaknesses were discovered and it is no longer approved for most cryptographic use cases

Answer 8

SHA-1

Question 9

Blank is improved SHA-1 to overcome potential weaknesses. It includes four versions. SHA-256 creates 256-bit hashes and SHA-512 creates 512-bit hashes. SHA -224(224 bit hashes) and SHA-384 (384 bit-hashes) created truncated versions of SHA-1 and SHA-512.

Answer 9

SHA-2

Question 10

Previously known as Keccak, blank is an alternative to SHA-2. It can create hashes the same size as SHA-2 (224 bits, 256 bits, and 512 bits)

Answer 10

SHA-3

Question 11

A blank occurs when the hashing algorithm creates the same hash from different inputs. This is not desirable.

Answer 11

Collision

Question 12

Validates an identity

Answer 12

Authentication

Question 13

prevents a party from denying an action

Answer 13

non-repudiation

Question 14

provides authentication, non-repudiation, and integrity

Answer 14

Digital signature

Question 15

A hash of an email message encrypted with senders private key

Answer 15

Digital signature

Question 16

encrypts data one bit at a time

Answer 16

stream ciphers

Question 17

Ciphers that encrypt data in blocks

Answer 17

Block ciphers

Question 18

A fixed length of string of bits similar to other hashing algorithms such as MD5 or SHA-256. This also uses a shared secret key to add some randomness to the result and only the sender and receiver know the key.

Answer 18

Hand-based Message Authentication Code (HMAC)

Question 19

A technique that increases the strength of stored passwords. Instead of adding salt to the password before hashing it, this technique applies a cryptographic stretching algorithm to the salted password

Answer 19

Key Stretching