Test 2

RC4

stream cipher; fast Uses key lengths of 8 to 2048 bits Most vulnerable to possibility of weak keys.

Hashing

takes an input and mathematically reduces it to a unique number known as a hash, which is not reversible.

RC

Rivest Ciphers -RC2 and RC5

SHA-2 includes what algorithms

SHA-256, SHA-384, and SHA-512 - all have longer hash results than SHA-1; more difficult to attack successfully requires more processing power to compute the hash.

Local packet delivery

applies to packets being sent out on a local network. Ethernet is common for local packet delivery

Ephemeral keys

are cryptographic keys that are used only once after they are generated.

Symmetric Encryption

Both the sender and the receiver of the message have the same key. must be a mechanism for key management.

Substitution

replacing an item with a different item

RC6

28 bit block size; keys sizes: 128, 192, 256. Resistant to brute force attacks Should provide adequate security for some time to come

IPv4

32bit

AES

A block cipher that separates data input into 128-bit blocks Can also be configured to use blocks of 192 or 256 bits. Key size affects the number of rounds used in the algorithm. Longer key versions are known as AES-192 and AES-256, respectively. Gold standard for symmetric encryption. No efficient attacks in existence

Media Access Control (MAC) address

A unique identifier assigned to network adapters by the manufacturer. This address is six octets in length and is written in hexadecimal.

Elliptic Curve Cryptography (ECC)

An algorithm that uses elliptic curves instead of prime numbers to compute keys. Elliptic curves are defined by this equation: y2 = x3 + ax2 + b Elliptic curves work because they have a special property—you can add two points on the curve together and get a third point on the curve.

OSI Layers

Application, Presentation, Session, Transport, Network, Data Link, Physical

Block vs. Stream

Block More memory to process Stronger High diffusion resistant to insertions/modifications Susceptible to error propagation Can provide for authentication and integrity verification Stream Faster than block in operaiton Difficult to implement low diffusion susceptible to insertions/modifications low error propagation Cannot provide for authentication and integrity verification

Twofish

Block cipher, utilizing 128-bit blocks with a variable-length key of up to 256 bits Uses 16 rounds and splits the key material into two sets

International Data Encryption Algorithm (IDEA)

Block mode cipher using 64-bit block size and 128-bit key. Full, eight-round IDEA shows that the most efficient attack would be to brute-force the key. Susceptible to weak key vulnerability, but easy to mitigate.

Blowfish

Block mode cipher, utilizing 64-bit blocks and a variable key length from 32 to 448 bits No weakness evident when implemented with the full 16-round version

Primary purpose of hashing protocols

By computing a digest of the message, less data needs to be signed by the more complex asymmetric encryption

Stream Ciphers

Ciphers that operate on each character or bit of a message (or data stream) one character/bit at a time.

Asymmetric Encryption

Commonly known as public-key cryptography. Uses a pair of keys A private key that is kept secret A public key that can be sent to anyone Security reliant upon resistance to deducing one key, given the other Involves two separate but mathematically related keys Keys are used in opposing fashion - one key undoes the actions of the other and vice versa Exchanges of keys via digital certificates

Symmetric Encryption Adv

Comparatively fast Few computational requirements

five components of security

Confidentiality, integrity, availability, authentication, and nonrepudiation Encryption addresses all components except availability

Secrecy Principles

Confusion Diffusion Perfect Forward Secrecy

Vigenere Cipher Process

Creating a substitution table Matching the password to the text it is meant to encipher with password repeated if needed to match all up with all plaintext characters Determining the cipher letter by matching the plaintext charter's row with the password character's column - ciphertext character is the intersecting character

Symmetric Encryption Algorithms

DES, 3DES, AES, and IDEA.

Domain Name System (DNS)

DNS translates names into IP addresses.

Digital Rights Management (DRM)

DRM is the process for protecting intellectual property from unauthorized use. A common example of DRM is the broadcast stream of digital satellite TV. DRM will also become very important in the industry of Software as a Service (SaaS).

how is cryptography

Data protection Data hiding Integrity checks Nonrepudiation services Policy enforcement Key management and exchange

3DES

Depending on the variant, it uses either two or three keys. Multiple encryption - goes through the DES algorithm three times.

Why doesn't RSA replace DES

Does not replace symmetric encryption because RSA is 100 times slower than DES!

Diffie-Hellman (DH) Uses

Electronic key exchange method of the Secure Sockets Layer (SSL) protocol TLS, SSH, and IPsec protocols Sharing of a secret key between two people who have not contacted each other before.

Cryptographic operations include

Encryption (for the protection of confidentiality) hashing (for the protection of integrity) digital signatures (to manage nonrepudiation) and a bevy of specialty operations such as key exchanges

Block Ciphers

Encrypts a message one block at a time

Ethernet

Ethernet is the most widely implemented Layer 2 protocol.

RSA

Exponentiation cipher Used for encryption and digital signatures Uses the product of two very large prime numbers 100 to 200 digits long and of equal length Relies on the difficulty of determining the number of numbers relatively prime to a large integer n

How does encryption ensure authentication

From hashing to key stretching to encryption and digital signatures, multiple techniques are used as part of the operations involved in authentication

3 Types of Encryption Algorithms

Hashing Symmetric Asymmetric

disadvantage of ICMP

ICMP has been greatly abused by attackers over the last few years. Attackers execute denial-of-service (DoS) attacks.

MD4

It is a fast algorithm, but it is subject to more attacks than more secure algorithms such as MD5. It has been shown to be vulnerable to collision.

Internet Control Message Protocol (ICMP)

It is used by network devices to determine such things as a remote network's availability, the length of time to reach a remote network, and the best route for packets to take when traveling to that remote network. ICMP can also be used to handle traffic flow. ICMP is a connectionless protocol designed to carry small messages quickly with minimal overhead or impact to bandwidth.

MD2

It takes a data of any length and produces a hash output of 128 bits

Encryption Algorithm use

Key escrow; digital rights management and intellectual property protection; digital signatures

Packet Delivery

Local and Remote delivery

Advantages of breaking the data up include

More effective sharing of bandwidth with other systems Not needing to retransmit the entire dataset if there is a problem in transmission

Quantum Cryptography

Quantum cryptography based on quantum mechanics, e.g., superposition and entanglement. Principle of most concern in quantum mechanics is that the measuring of data disturbs the data. Quantum key distribution applies quantum cryptography in determining whether data has been intercepted in transit. Other fields include quantum cryptanalysis and post-quantum cryptography.

How does encryption ensure confidentiality

Secrecy of data is ensured by: Strength of the algorithms Length of the keys

SHA

Secure Hash Algorithm

Strength of a cryptographic algorithm depends on

Size of the key and the resulting keyspace, a set of every possible key value

Packets

Small chunks of information that have been carefully formed from larger chunks of information.

Hashing Functions uses

Storing passwords Signing messages Maintaining message integrity

Symmetric vs. Asymmetric

Symmetric encryption tends to be faster, is less computationally involved, and is better for bulk transfers. Suffers from a key management problem in that keys must be protected from unauthorized parties Asymmetric methods resolve the key secrecy issue with public keys, Add significant computational complexity that makes them less suited for bulk encryption

How does encryption ensure integrity

The ability to independently make sure that a document has not been tampered with is very important to commerce. The hash functions compute the message digests, and this guarantees the integrity of the message

How does encryption ensure nonrepudiation

The message sender cannot later deny that they sent the message. This is important in electronic exchanges of data, because of the lack of face-to-face meetings. Nonrepudiation is tied to asymmetric cryptography and cannot be implemented with symmetric algorithms.

routing

The process of moving packets from one network to another

One-Time Pad

Theoretically perfect and unbreakable Key the same size or larger than the material being encrypted Plaintext XOR'ed against the key to produce the ciphertext "Perfect" characteristic due to the size of the key

Digital Signatures

Touted as the key to truly paperless document flow. Digital signatures are based on both hashing functions and asymmetric cryptography. Both encryption methods play an important role in signing digital documents.

Symmetric Encryption Disadv

Two geographically distant parties both need to have a key that matches the other key exactly. Simple keys can quickly be brute-forced. Secure key exchange can be an issue.

DH

Uses large prime numbers to work. Two users agree to two numbers, P and G, with P being a sufficiently large prime number and G being the generator. Both users pick a secret number, a and b. Then both users compute their public number:

RIPEMD

Versions include original 128-bit hash; RIPEMD-160; RIPEMD-256; and RIPEMD-320

MD5

Very similar to the MD4 algorithm, only slightly slower and more secure Creates a 128-bit hash of a message of any length and segments the message into 512-bit blocks`

Trapdoor functions

are difficult to process without the key but easy to process when you have the key. ex Computers can easily multiply very large primes with hundreds or thousands of digits but cannot easily factor the product.

Problems with DES

Weak keys - keys that are less secure than the majority of keys allowed in the keyspace of the algorithm Semiweak keys - two keys that will encrypt plaintext to identical ciphertext

Maximum Transmission Unit (MTU)

a factor in determining the number of packets into which a message must be broken.

Vigenère cipher

a polyalphabetic substitution cipher that depends on a password

shift cipher

a simple substitution cipher where the letters are coded by moving a certain amount forwards or backwards in the alphabet.

RIPEMD-160

an algorithm based on MD4 but uses two parallel channels with five rounds Output consists of five 32-bit words to make a 160-bit hash

Remote packet delivery

applies to packets being delivered to a remote system, such as across the Internet. IP works for remote delivery

Data Encryption Standard (DES)

block cipher Block size of 64 bits—64 bits of plaintext outputs 64 bits of ciphertext. 56-bit key length Performs a substitution and permutation (a form of transposition) based on the key 16 times on every 64-bit block.

RC5

block cipher, multiple variable elements, RC6 is newer version.

Transposition

changing the order of items

Differential cryptanalysis

compares the input plaintext to the output ciphertext to try and determine the key used to encrypt the information

Star Topology

components connected to a central point

Ring topology

components connected to each other in a closed loop with each device directly connected to two other devices

Bus topology

components connected to the same cable, often called "the bus" or "the backbone"

Collision Attack

compromises a hash algorithm. Occurs when an attacker finds two different messages that hash to the same value Very difficult and requires generating a separate algorithm that attempts to find a text that will hash to the same value of a known hash

RC2

designed as DES replacement, 8 to 1024 bit key size, 64 bit block size, keys below 64 bit are vulnerable.

Asymmetric algorithms

employ employing two keys, a public key and a private key, making up what is known as a key pair.

Key Escrow

escrow refers to keeping a copy of the encryption key with a trusted third party. Can be used to retrieve your key in case of emergency Can be used by law enforcement Can negatively affect your security

Uses of Steganography

hide illegal material. Pornography Covert communication by terrorist networks

Key Management

includes anything having to do with the exchange, storage, safeguarding, and revocation of keys.

TCP

is a "connection-oriented" protocol specifically designed to provide a reliable connection between two hosts exchanging data. TCP is designed to ensure packets processed in the same order in which they were sent. Packet sequence number shows where each packet fits into the overall conversation. 3 way handshake

Address Resolution Protocol (ARP)

protocal used to identify a mac address

Key stretching

is a mechanism that takes what would be weak keys and "stretches" them to make the system more secure against brute-force attacks. A typical methodology involves increasing the computational complexity by adding iterative rounds of computations

Diffusion

is a principle that the statistical analysis of plaintext and ciphertext results in a form of dispersion rendering one structurally independent of the other.

Confusion

is a principle to affect the randomness of an output.

Perfect forward secrecy

is a property of a public key system in which a key derived from another key is not compromised even if the originating key is compromised in the future.

key

is a special piece of data used in both the encryption and decryption processes

Work factor

is a subjective measurement of the time and effort needed to perform operations. Low work factor means a larger keyspaces are needed

Session Keys

is a symmetric key used for encrypting messages during a communication session. Generated from random seeds Used for the duration of a communication session Session keys offer the advantages of: Symmetric encryption, speed, strength, simplicity Significant levels of automated security

protocol

is an agreed-upon format for exchanging or transmitting data between systems.

CAST

is an encryption algorithm that is similar to DES in its structure. Uses 64-bit block size for 64- and 128-bit key versions 128-bit block size for the 256-bit key version

UDP

is known as a "connectionless" protocol. It has very few error recovery services and no guarantee of packet delivery. Sender has no idea whether the packets were successfully received or whether they were received in order. UDP is considered to be an unreliable protocol. UDP is good for time synchronization requests, name lookups, and streaming audio. It is a fairly "efficient" protocol in terms of content delivery versus overhead.

Ciphertext

is the encrypted output

Message digest (MD)

is the generic version of one of several algorithms designed to create a message digest or hash from data input into the algorithm. MD algorithms work in the same manner as SHA. A secure method employed to compress the file and generate a computed output of a specified number of bits.

Plaintext

is the unencrypted input text

Transport encryption

is used to protect data that is in motion.

Hashing Functions

mathematical function that performs a one-way function. i.e. once the algorithm is processed, there is no feasible way to use the ciphertext to retrieve the plaintext.

IP Packets

often called datagrams Header - contains all of the information needed to describe the packet. Data section - sometimes called the payload

A wide area network (WAN)

tends to be larger, covering more geographic area, and consists of two or more systems in geographically separated areas. They are connected by leased lines, radio waves, satellite relays, microwaves, or even dial-up connections.

Steganography

the art and science of hiding information by embedding messages within other, seemingly harmless messages

Key Exchange

the central foundational element of a secure symmetric encryption system.

Problems with 3DES

the longer key makes it more resistant to attacks but similar issues to DES

local area network (LAN)

typically is smaller in terms of size and geographic coverage and consists of two or more connected devices. Home networks and most small office networks can be classified as LANs.

Symmetric algorithms (or shared secret algorithms)

use the same key is used for encryption and decryption

Linear cryptanalysis

uses both plaintext and ciphertext; puts the plaintext through a simplified cipher to try and deduce what the key is likely to be in the full version of the cipher

Mixed topology

uses more than one topology at the same time

SHA-1

was one of the more secure hash functions. But it has been found to be vulnerable to a collision attack.

transposition cipher

where the same letters are used but the order is changed