Cyber Security wk 13

Monoalphabetic ciphers:

-Caesar cipher -ROT13

examples of early steganography

-Poking holes above letters in newspapers -Templates or algorithms applied to a preselected location on a page -(Vietnam) Jeremiah Denton - blinked "TORTURE" repeatedly in morse code while being interviewed on film as a North Vietnam POW. - (Cold War) CIA - used shoelaces to secretly communicate between agents.

Polyalphabetic ciphers:

-Vigenere Cipher -One-Time Pad (aka "Verman" cipher) -XOR

Cryptography can provide 5 basic protections

1. Confidentiality 2. integrity 3. Authentication 4. Non-repudiation 5. Obfuscation

Cryptography can provide protection to data as that data resides in any of three states:

1. Data in Processing 2. Data in Transit 3. Data At rest

- Secure hashing algorithms have the following characteristics:

1. Fixed size: Short and long data sets have the same size hash 2. Unique: Two different data sets cannot produce the same hash 3. Original: Data set cannot be created to have a predefined hash 4. Resulting hash cannot be reversed to determine original plaintext

Three categories of cryptographic algorithms

1. Hash Algorithms 2. Symmetric cryptographic algorithms 3. Asymmetric Cryptographic algorithms

Modern Cryptographic algorithms depend on:

1. Keyspace 2. Quality of randomness of numbers

Examples of Transposition:

1. Rail fence cipher 2. Scytale (staff) cipher

Other cryptographic constraints include:

1. Speed 2. Size 3. Weka keys 4. Key length 5. Longevity 6. Predictability 7. Reuse 8. Entropy 9. Computational overhead

to thwart the threat of quality of randomness of number (PRNG) you must ensure

1. diffusion 2. Confusion

Approved by the NIST in 2000 to replace -DES Performs three steps on every block (128 bits) of plaintext -Designed to be secure well into the future

Advanced Encryption Standard (AES)

The extent of change to the hash value resulting from one change in the data is referred to as the

Avalanche effect

plays on probabilities of a value showing/not showing - if you randomly take 23 people born in the USA, there is a 50% probability two of them will have the same birthday. - With PRNG, a similar principle applies, in that all 0s, all 1s, and certain patterns ("1010101010") are less likely to occur. This allows for more targeted and accelerated brute force

Birthday attack

pseudorandom number generator (PRNG) opens the door to a

Birthday attack

cipher that manipulates an entire block of plaintext at one time.

Block Cipher

Rotate the alphabet 3 letters ▪ Double vowels and double consonant survive encryption!!! (weakness) - Clear pattern make sit easy to brute force ▪ Example: HAPPY → KDSSB

Caesar cipher

is the scrambled and unreadable output of encryption.

Ciphertext

Unencrypted data that is not intended to be encrypted is cleartext (it is "in the clear").

Cleartext

when 2 diff data sets have the exact same hash

Collision

Hashing is primarily used for BLANK purposes

Comparison

the key does not relate in a simple way to the ciphertext

Confusion

The study of ciphertext, ciphers and cryptosystems with the aim of understanding how they work and defeating or weakening them

Cryptanalysis

The practice of transforming information so that it is secure and cannot be understood by unauthorized person

Cryptography

Based on product originally designed in early 1970s -Uses a 56-bit key and is a block cipher -it is no longer considered suitable for use. -the U.S. government officially adopted DES as the standard for encrypting unclassified information

Data Encryption Standard (DES)

data stored on electronic media.

Data at rest

Data actions being performed by "endpoint devices," such as printing a report from a desktop computer.

Data in Processing

Actions that transmit the data across a network

Data in Transit

The process of changing encrypted text into the original text.

Decryption

if a single character of plaintext is changed then it should result in multiple characters of the ciphertext changing

Diffusion

The process of changing plaintext into ciphertext.

Encryption

The measure of randomness of a datagenerating function

Entropy

An algorithm that creates a unique digital fingerprint.

Hash Algorithm

purpose is not to create ciphertext that can later be decrypted.

Hash algorithms

A hash variation providing improved security - Uses a "shared secret key" possessed by sender and receiver - Receiver uses a key to decrypt the hash

Hashed Message Authentication Code (HMAC)

The process of creating a digital fingerprint.

Hashing

The ability to quickly recover from resource vs. security constraints.

High Resiliency

as that which protects the C.I.A. of information through products, people and procedures on devices that store, manipulate and transmit data.

Information Security

The length of the key, if it is larger it increases the work factor"

Keyspace

A category of cryptography that has fewer features and is less robust than normal cryptography. Being dveloped mainly for low-powered devices

Lightweight cryptography

Most well-known of the MD hash algorithms - Message length padded to 512 bits -uses four variables of 32 bits - Weaknesses in compression function could lead to collisions - Some security experts recommend using a more secure hash algorithm - is no longer considered suitable for use.

Message Digest 5 (MD5)

which exchanges one character for another.

Obfuscation

The only unbreakable cipher IF IMPLEMENTED CORRECTLY! -Key is used once and never again -Running key with maximum randomization -Perfect protection of the one-time key by both parties

One-Time Pad AKA OTP (or Verman cipher)

Because the key must be kept private (confidential), symmetric encryption is also called

Private Key encryption

Any time a pattern exists within the values, the algorithm is at risk of brute force

Quality of randomness of numbers

Rotate the alphabet 13 (half of the alphabet) letters - Like Caesar cipher, very susceptible to brute force through letter-frequency analysis (also known as a Ciphertext Only Attack). -Also susceptible to a Known Plaintext Attack, whereby the unauthorized party looks for known patterns in communication (e.g., signature lines)

ROT!3

The primary design feature is two different and independent parallel chains of computation - The results are combined at end of process - Several version of RIPEMD - all versions of RIPEMD are based on the length of the digest created, ▪ RIPEMD -128, RIPEMD -256, and RIPEMD -320

Race Integrity Primitives Evaluation Message Digests(RIPEMD)

uses a zig zag, Old example of a cipher that explains transposition well, Key conveys pattern to sender and recipient

Rail Fence Cipher

A limitation in providing strong cryptography due to the "tug-of-war" between the available resources (time and energy) and the security provided by cryptography.

Resource vs. Security Constraint

takes as input a string of any length and returns a string of any requested variable length. This function repeatedly applies a process on the input that has been padded with additional characters until all characters are used (absorbed in the sponge).

SPonge function

o Generals carried staffs of equal length and taper. o Leather strap wrapped around sender's staff o Message written on leather strap while still wrapped around staff o Leather strap with encoded message then transported to receiver o Receiver would wrap leather strap around matching staff to decode/receive

Scytale (staff) cipher

More secure than MD - SHA-2 is currently considered to be a secure hash - SHA-3 was announced as a new standard in 2015 and may be suitable for low-power devices

Secure Hash algorithm (SHA)

is one cryptographic method that does not encrypt data. Rather, it hides the existence of the data.

Steganography

Hiding the existence of data within another type of file, such as an image file

Steganogrpahy

Modern stenography example (setghide)

Steghide prompts for a passphrase, which is used as an encryption key. To date, nobody has found a way to reliably detect the presence of an embedded message when it is first encrypted.

An algorithm that takes one character and replaces it with one character. works one character at a time

Stream Cipher

Replacing letters within a message -Two types - Monoalphabetic and Polyalphabetic

Substitution

category/method of encryption that exchanges one character for another.

Substitution

in Block ciphers:

The plaintext message is divided into separate blocks of 8 to 16 bytes, and then each block is encrypted independently. For additional security, the blocks can be randomized.

- encryption method that inovles Reordering letters within a message - Also referred to as "obfuscation" and/or "permutation"

Transposition

-Designed to replace DES -Uses three rounds of encryption Ciphertext of first round becomes input for second -Most secure versions use different keys each round -it is no longer considered the most secure symmetric cryptographic algorithm. -employs a total of 48 iterations in its encryption (3 iterations × 16 rounds)

Triple Data Encryption standard (3DES)

- Hashing is primarily used for file comparison purposes and the contents cannot be used to reveal original data set T or F?

True

. Cryptography is usually accomplished through "scrambling" the information so that only approved recipients (either human or machine) can understand it. T or F?

True

A common scheme (in steganography) is to hide data in the file header fields that describe the file, between sections of the metadata (data that is used to describe the content or structure of the actual data), or in the areas of a file that contain the content itself. T or F?

True

A fundamental difference in cryptographic algorithms is the amount of data processed at a time T or F?

True

Another difference in cryptographic algorithms is the keyspace, which determines the work factor required to brute force T or F?

True

Applications that require extremely fast response times also face cryptography limitations T or F?

True

DES effectively catapulted the study of cryptography into the public arena T or F?

True

Hashing is intended to be ONE WAY in that its digest cannot be reversed to reveal the original set of data T or F?

True

Hashing is often used as a check to verify that the original contents of an item have not been changed T or F?

True

Higher the keyspace, the more guesses required to brute force T or F?

True

I is important that there be high resiliency in cryptography T or F?

True

Ideally, a cryptographic algorithm should have low latency T or F?

True

Low-powered devices need to be protected form threat actors T or F?

True

Proprietary algorithms, on the other hand, have not been properly vetted and will likely contain flaws and, thus, should not be used. T or F?

True

Software relies upon a pseudorandom number generator (PRNG) that is only somewhat random T or F?

True

Stream ciphers are less secure because the engine that generates the stream does not vary T or F?

True

The definition of Cryptography DOES NOT include encryption T or F?

True

The number of small electronic devices (low-power devices) has grown significantly T or F?

True

The original cryptographic algorithms for encrypting and decrypting data are symmetric cryptographic algorithms T or F?

True

obfuscation cannot by itself be used as a general cybersecurity protection. T or F?

True

Uses multiple different alphabets (with rotation) in matrix form to encrypt -Key must be same length as message -Message alphabet across the top - Key alphabet runs top-bottom (look at slide)

Vigenere Cipher

While they date back to hundreds of years BC, the origins of contemporary stenography originate from

World War II

o Performs a simple comparison of two binary bits - When both are same value (1s or 0s), 0 is returned -When they are different (1 and 0), 1 is returned -Can be used within one-time pad and other ciphers

XOR

Consists of procedures based on a mathematical formula used to encrypt and decrypt the data. Also called a cipher.

algorithm

this fingerprint, represents the contents (does not tell us the nature of the content)

digest (sometimes called a message digest or hash)

Cryptography protects integrity by:

ensuring information is correct and unaltered

cryptography protect confidentiality by:

ensuring only authorized parties can view it

Cryptography protects authentication by:

ensuring sender can be verified

is a mathematical value entered into the algorithm to produce the ciphertext.

key

A small amount of time that occurs between when a byte is input into a cryptographic algorithm and the time the output is obtained.

low latency

Small electronic devices that consume very small amounts of power.

low-power devices

Cryptography protect Obfuscation by:

making information obscure or unclear

The process of proving that a user performed an action.

nonrepudiation

Unencrypted data that is input for encryption or is the output of decryption is called

plaintext

Cryptography protects Non-repudiation by:

proving that a user performed an action

se the same single key to encrypt and decrypt a message.

symmetric cryptographic algorithms

Block ciphers are considered more secure because the output is more random bc:

the cipher is reset to its original state after each block is processed.

Symmetric cryptography can provide strong encryption if:

the key is kept secure between the sender and all the recipients

why is it difficult to add cryptography to low-powered devices?

to perform their computations, cryptographic algorithms require time and energy, both of which are typically in short supply for low-power devices and applications needing ultra-fast response times