Lesson 6 Encryption Fundamentals
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)
