Cryptography Concepts

Question 1

Integrity protection operations

Answer 1

When Materials, Plaintext, needs to be protected from unauthorized interception or alteration, it is encrypted into ciphertext.

Question 1

Key exchange

Answer 1

Key exchange (also known as “key establishment”) is any method in cryptography by which cryptographic keys are exchanged between two parties, allowing use of a cryptographic algorithm.

Question 2

Steganography

Answer 2

Greek steganos, or “covered,” and graphie, or “writing”) is the hiding of a secret message within an ordinary message and the extraction of it at its destination.

Question 3

A digital signature

Answer 3

is a mathematical technique used to validate the authenticity and integrity of a message, software or digital document.

Question 4

A digital certificate

Answer 4

is an electronic “passport” that allows a person, computer or organization to exchange information securely over the Internet using the public key infrastructure (PKI).

Question 5

A public key infrastructure (PKI)

Answer 5

supports the distribution and identification of public encryption keys, enabling users and computers to both securely exchange data over networks such as the internet and verify the identity of the other party.

Question 6

A public key certificate

Answer 6

is a digitally signed document that serves to validate the sender’s authorization and name.

Question 7

Crypto Analysis

Answer 7

is the process of analyzing available information in an attempt to return the encrypted message to its original form.

Question 8

Cryptographic process involve

Answer 8

algorithms and increasingly complex keys.

Question 9

There are two types of cryptanalysis:

Answer 9

• Differential Cryptanalysis
• Linear Cryptanalysis

Question 10

Differential Cryptanalysis

Answer 10

is done by comparing the input plaintext to the output ciphertext to try to determine the key used to encrypt the information.

Question 11

Linear Cryptanalysis

Answer 11

is similar in that it uses both plaintext and ciphertext, but it puts the plaintext through a simplified cipher to try to deduce what key is likely to be In the full version of the cipher.

Question 12

There are two Major types of key Algorithm (Cryptographic Techniques):

Answer 12

• Symmetric Key Algorithm
• Asymmetric Key Algorithm

Question 13

Symmetric-key algorithms

Answer 13

Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both encryption of plaintext and decryption of ciphertext.

The keys may be identical or there may be a simple transformation to go between the two keys.

Question 14

Asymmetric Cryptography,

Answer 14

Asymmetric cryptograhy, also known as public key cryptography, uses public and private keys to encrypt and decrypt data.

Public-key cryptography, or asymmetric cryptography, is an encryption scheme that uses two mathematically related, but not identical, keys - a public key and a private key. …

The public key is used to encrypt and the private key is used to decrypt.

Question 15

Hashing Functions

Answer 15

Hashing functions are commonly used encryption methods.

A Hash Function is a special mathematical function that performs one-key encryption.

There is no feasible way to generate two different plaintexts that compute to the same hash value.

Common use of hashing algorithms are to store computer password and to ensure message integrity.

Question 16

Cryptography

Answer 16

is the science of encrypting, or hiding, information.

According to Shannon, there are two basic approaches to Encryption:
Confusion
Diffusion

Question 17

Confusion

Answer 17

Encryption operation where the relationship between
cleartext and ciphertext is obscured.
The key does not relate in a simple way to the ciphertext. In Particular, each character of the ciphertext should depend on several parts of the key.

Question 18

Diffusion

Answer 18

Diffusion:- Encryption by spreading out the influence of one
cleartext letter over many ciphertext letters.

                - If we change a character of the plaintext, then several characters of the ciphertext should change, and similarly, if we change a character of the ciphertext, then several characters of the plaintext should change.

Question 19

Non-Repudiation

Answer 19

Is a property that deals with the ability to verify that a message has been sent and received so that the sender (or receiver) cannot refute sending (receiving) the information.

Question 20

Key Escrow

Answer 20

is a system by which your private key is kept both by you and a third party.

• provide a method of obtaining a key in the event that the key holder is not available.
• can solve many problems resulting from an inaccessible key, and the nature of cryptography makes the access of the data impossible without the key.