Lesson 6 Encryption Fundamentals

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Quantum Cryptography

-Makes the discrete logarithm problem quite solvable -Renders the discrete algorithms obsolete

Quantum computing

-Relies on qubits or quantum bits that store data via the polarization of a single photon - Provides advances in numerous aspects, such as data mining, artificial intelligence, and other applications

What is a digital signature?

A piece of encrypted data added to other data to verify the sender

What is an Atbash cipher?

A primitive and easy to break cipher that reverses the alphabet. A becomes Z, etc.

If you are using a block cipher to encrypt large amounts of data, which of the following would be the most important consideration when deciding which cipher to use (assuming all of your possible choices are well known and secure)?

Speed of the algorithm

Which of the following is the most common legitimate use for a password cracker?

Testing the encryption of your own network

Rijndael Algorithm

The Algorithm used by AES

Decryption

The process of un-encrypting an encrypted message.

Brute Force

To try to crack a password by simply trying every possible combination.

What is the purpose of a certificate?

To validate the sender of a digital signature or software

T/F: A Digital Certificate contains a public key and some means to verify whose public key it is

True

T/F: A digital certificate X.509 is a digital document that contains a public key signed by the trusted third party

True

T/F: Steganography is the art and science of hiding information within other non-secret text or data

True

T/F: Steganography is a form of security through obscurity

True.

Voluntary Tunneling

Tunneling that allows the user to determine the parameters of a VPN tunnel.

Stealth Files 4

Works with sound files, video files, and image files;

Which binary mathematical operation can be used for a simple encryption method?

XOR

MD5 - Message Digest 5

a 128 bit hash specified by RFC 1321 and designed by Ron Rivest

If the Caesar cipher for 'believe you can' is written as E H O L H Y H B R X F D Q, then what will be the ciphertext of 'dreams come true'

guhdpv frph wuxh

HAVAL

produces hashes of different lengths and allows users to specify the number of rounds (3, 4, or 5) to be used to generate the hash

Which of the following encryption algorithms is a block cipher, and uses the Rijndael algorithm?

AES

Which of the following has three different key sizes that it can use?

AES

A block cipher that works on 128 bit blocks and can have one of three key sizes of 128, 192, or 256 bits

AES (advanced encryption standard)

AES

Advanced Encryption Standard, a modern symmetric cipher that is widely used.

A symmetric block cipher that uses variable-length key ranging from 32-448 bits

Blowfish

Which encryption algorithm uses a variable length symmetric key?

Blowfish

Attempts every possible combination of characters until the correct one is uncovered

Brute-Force

Which of the following is the oldest known encryption method?

Caesar Cipher

The attacker can see cleartexts to be encrypted and obtain the corresponding ciphertexts

Chosen Plaintext

SNOW

Conceals messages in ASCII text by appending whitespace to the end of lines

Which of the following is a symmetric key system using blocks?

DES

A fiestel cipher that uses short keys and relies on complex procedures to protect its information

DES ( Data encryption standard)

A federal information processing standard for digital signatures

DSA (Digital signature algorithm)

DES

Data Encryption Standard. A symmetric cryptography algorithm first published in 1977, no longer considered secure due to the small key size.

Focuses on finding a relationship between the changes that occur in the output bits as a result of changing some of the input bits

Differential Cryptanalysis

Allows two parties to establish a shared key over an insecure channel

Diffie- Hellman

A public key encryption method based on elliptic curve theory that can be used to create faster, smaller, more efficient cryptographic keys

Elliptic curve

Multi-Alphabet Substitutions

Encryption methods that use more than one substitution alphabet.

T/F: Steganography uses a linear approximation to describe the behavior of the block cipher

False

Why is the XOR mathematical operation not secure?

It does not change letter or word frequency

which of the following is the primary weakness in the Caesar Cipher?

It does not disrupt letter frequency

What is the primary advantage of the DES encryption algorithm?

It is relatively fast

The attacker has access to both the cleartext and its encrypted text

Known plaintext

An improvement on the Caesar cipher that uses more than one shift is called?

Multi-Alphabet substitution

Why is encryption an important part of security?

No matter how secure your network is, the data being transmitted is still vulnerable without encryption.

ASCII Code

Numeric codes used to represent all standard alphanumeric symbols. There are 255 different ASCII codes.

Caesar Cipher

One of the oldest encryption algorithms. It uses a mono-alphabetic cipher.

Binary Operations

Operations on base 2 numbers. The operations include XOR, OR, and AND.

PGP

Pretty Good Privacy. A widely used tool that has symmetric and asymmetric algorithms, often used to encrypt email.

What type of encryption uses a different key to encrypt the message than it uses to decrypt the message?

Public Key

Which of the following is an encryption method developed by three mathematicians in the 1970s?

RSA

A public key encryption method used to encrypt a message without the need to exchange a key separately

RSA ( Rivest- Shamir- Adleman)

If the ROT 13 cipher for 'think less live more' is written as guvax yrff yvir zber then what will the plaintext of jbexuneqfgnluhzoyr be?

work hard stay humble

RIPEMD-160 (RACE Integrity Primitives Evaluation Message Digest)

A fast cryptographic hash function tuned towards software implementations on 32-bit architectures

Quantum Entanglement

A phenomena from quantum physics where two subatomic particles are related in such a way that a change to the state of one instantaneously causes a change to the state of the other.

Quantum encryption

A process that uses quantum physics to encrypt data.

RSA

A public key encryption method developed in 1977 by 3 mathematicians, Ron Rivest, Adi Shamir, and Len Adleman. The name RSA is derived from the first letter in each mathematicians last name.

Blowfish

A well- know symmetric block cipher created by Bruce Schneier.

X.509

A widely used standard for digital certificates.

What size key does the DES algorithm use?

56-bit

SHA-1 / Secure Hash Algorithm 1

A 160-bit hash function designed by the NSA ( National Security Agency) to be a part of the Digital Signature Algorithm

IDEA (International Data Encryption Algorithm)

A block cipher designed as a replacement for DES.

Digital Signature

A cryptographic method of verifying a file or sender.

Who issues certificates?

A private certificate authority

Mono-Alphabetic Cipher

An encryption cipher using only one substitution alphabet.

Symmetric Key System

An encryption method where the same key is used to encrypt and decrypt the message.

Invisible Secrets

Encrypts confidential file and folder structures and allows users to hide files form other users

T/F: steganography utilizes the most significant bits in a file to store data

False

T/F: A digital Certificate is distributed by RA which acts as a proxy between users and CAs.

False. It is distributed by PKI ( public key infrastructure) an arrangement that binds public keys with respective user identities by means of a CA (Certificate Authority)

T/F: A digital Certificate is issued by PKI who digitally signs and publishes the public key bound to a given user

False. It is issued by CA (Certificate Authority) who digitally signs and publishes the public key bound to a given user.

Looks at the blocks of an encrypted message to determine if any common patterns exist and deduces the method used to encrypt the data

Frequency analysis

QuickStego

Hides text in pictures and only its users can read the hidden text messages

A block cipher that uses sub-keys generated from the key to carry out a series of modular arithmetic and XOR operations on segments of the 64bit plaintext block

IDEA (International Data Encryption Algorithm)


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