Cryptography is the science of secret writing and involves encrypting plaintext messages into ciphertext. There are two main techniques for encryption: symmetric encryption where the sender and receiver share the same key, and public key encryption where different keys are used. Common terms in cryptography include plaintext, ciphertext, encryption/decryption algorithms, and keys. The secrecy of keys is more important than the algorithms themselves for security. Longer keys provide stronger encryption but are more computationally expensive. Cryptanalysis involves attempts to break encryption by discovering keys or plaintext.
Overview of Symmetric Ciphers,Stream ciphers
The life cycle and management of keys,Classical encryption standards,Basic terminology,Symmetric cipher model,
Unconditional& computational security,
steganography and cryptography
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Overview of Symmetric Ciphers,Stream ciphers
The life cycle and management of keys,Classical encryption standards,Basic terminology,Symmetric cipher model,
Unconditional& computational security,
steganography and cryptography
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This presentation will show you the basics of cryptography.
Main topics like basic terminology,goals of cryptography,threats,types of cryptography,algorithms of cryptography,etc. are covered in this presentation.If you like this presentation please do hit the like.
a performance analysis of generalized key scheme block cipher (gksbc) algorit...INFOGAIN PUBLICATION
Information is a commodity. Information has economic value and production of it incurs cost. Securing the information is posing a considerable challenge. The cryptographic technology plays a leading role in securing the owners right on produced information. A continuous development of new encryption systems are necessitated with the advancement in security and efficiency needs. Cryptanalytic studies have demonstrated the superior capability of recently developed Generalized Key Scheme Block Cipher (GKSBC) algorithm in terms of stability, execution time and encryption quality compared to standard security algorithms. This paper proposes to evaluate the enduring capacity of GKSBC to various cryptanalytic attacks viz., Brute – Force Attack, Differential Cryptanalysis, Integral Cryptanalysis, Linear Cryptanalysis and Rectangle attack. None of the traditional attacks are designed to decrypt GKSBC encryption as the use of key scheme is different in it and therefore robust to the conventional cryptanalytic attacks.
What is cryptography,its types,two algorithms i.e RSA and DES.
explained well and referenced the slide share too to give more precise presentation. Thank you.
This is a powerpoint presenation for cryptography and encryption algorithm for cybersecurity as welll as cyberattacks, this address intrusion and detection of spams, malware, DoS, phishing etc..therefore we provide a solution with the use of machine learning alogorithms to minimize the attacks on databeses and networks/softwares and hardwares.
Topics listed below are explained in the PPT:
Introduction
CIA Triad
Mechanisms of Cryptography
OSI Security Architecture
Security Attacks
Security Mechanisms
Security Services
Cryptography vs Steganography
Network Security Model
Cryptographic techniques
Stream Cipher vs Block cipher
Encryption is a process of converting a message, image, or any other .pdfrachanaprade
Encryption is a process of converting a message, image, or any other form of data into encoded
data that can only be decoded by someone who can decrypt the message (usually with a key or
the like). The science of writing secret codes is called cryptography For thousands of years,
cryptography has made secret messages that only the sender and recipient could read, even if
someone captured the messenger and read the coded message. A secret code system is called a
cipher. A good encryption algorithm should produce output that looks random to a bystander but
is easily decipherable with the correct key. Thus, encryption algorithms make use of pseudo-
random encryption keys. Let's start with some definitions: - Encryption or Enciphering: the
process of encoding messages to make them unreadable. This algorithm has two inputs: a
plaintext and a secret key. - Decryption or deciphering: making encrypted messages readable
again by decoding them (recovering the plaintext from ciphertext). - Cipher: an algorithm for
performing encryption and decryption. - Plaintext: the original message. - Ciphertext: the
encrypted message. Note: a ciphertext still contains all of the original message information, even
if it looks nonsense. - Secret key; the same key used for encryption and decryption. -
Cryptography, the science of studying ciphers. For this project, you need to develop a game that
converts normal English words into secret codes. In order to convert, the program randomly
applies an encryption algorithm to any given message. The algorithms you need to implement
include Substitution, Playfais Caesas Transposition, Product, and RSA ciphers. 1. Substitution
cipher, replacing each letter of the alphabet in the plaintext with a different letter in the
ciphertext. For example, if you want to encrypt the word 'Cat', you need to come up with a
substitution for each plaintext letter to a ciphertext letter. For example, you may substitute the
letter ' a ' with the letter ' o '. The rule is that the letter we substitute can only be used once. So,
the letter 'o' is crossed off as it has already been used. The same would be applied to all
alphabetic letters.
1. Substitution cipher; replacing each letter of the alphabet in the plaintext with a different letter
in the ciphertext. For example, if you want to encrypt the word 'Cat'; you need to come up with a
substitution for each plaintext letter to a ciphertext letter, For example. you may substitute the
letter 'a' with the letter ' 0 . The rule is that the letter we substitute can only be used once. So, the
letter 'o' is crossed off as it has already been used. The same would be applied to all alphabetic
letters. You can also substitute a letter with itself. If you are not familiar with this cipher. please
visit: Substitution cipher Page 3 of 5 2. Playfair cipher is a digraph substitution cipher. It
employs a table where one letter of the alphabet is omitted, and the letters are arranged in a 55
grid. For more informat.
This presentation will show you the basics of cryptography.
Main topics like basic terminology,goals of cryptography,threats,types of cryptography,algorithms of cryptography,etc. are covered in this presentation.If you like this presentation please do hit the like.
a performance analysis of generalized key scheme block cipher (gksbc) algorit...INFOGAIN PUBLICATION
Information is a commodity. Information has economic value and production of it incurs cost. Securing the information is posing a considerable challenge. The cryptographic technology plays a leading role in securing the owners right on produced information. A continuous development of new encryption systems are necessitated with the advancement in security and efficiency needs. Cryptanalytic studies have demonstrated the superior capability of recently developed Generalized Key Scheme Block Cipher (GKSBC) algorithm in terms of stability, execution time and encryption quality compared to standard security algorithms. This paper proposes to evaluate the enduring capacity of GKSBC to various cryptanalytic attacks viz., Brute – Force Attack, Differential Cryptanalysis, Integral Cryptanalysis, Linear Cryptanalysis and Rectangle attack. None of the traditional attacks are designed to decrypt GKSBC encryption as the use of key scheme is different in it and therefore robust to the conventional cryptanalytic attacks.
What is cryptography,its types,two algorithms i.e RSA and DES.
explained well and referenced the slide share too to give more precise presentation. Thank you.
This is a powerpoint presenation for cryptography and encryption algorithm for cybersecurity as welll as cyberattacks, this address intrusion and detection of spams, malware, DoS, phishing etc..therefore we provide a solution with the use of machine learning alogorithms to minimize the attacks on databeses and networks/softwares and hardwares.
Topics listed below are explained in the PPT:
Introduction
CIA Triad
Mechanisms of Cryptography
OSI Security Architecture
Security Attacks
Security Mechanisms
Security Services
Cryptography vs Steganography
Network Security Model
Cryptographic techniques
Stream Cipher vs Block cipher
Encryption is a process of converting a message, image, or any other .pdfrachanaprade
Encryption is a process of converting a message, image, or any other form of data into encoded
data that can only be decoded by someone who can decrypt the message (usually with a key or
the like). The science of writing secret codes is called cryptography For thousands of years,
cryptography has made secret messages that only the sender and recipient could read, even if
someone captured the messenger and read the coded message. A secret code system is called a
cipher. A good encryption algorithm should produce output that looks random to a bystander but
is easily decipherable with the correct key. Thus, encryption algorithms make use of pseudo-
random encryption keys. Let's start with some definitions: - Encryption or Enciphering: the
process of encoding messages to make them unreadable. This algorithm has two inputs: a
plaintext and a secret key. - Decryption or deciphering: making encrypted messages readable
again by decoding them (recovering the plaintext from ciphertext). - Cipher: an algorithm for
performing encryption and decryption. - Plaintext: the original message. - Ciphertext: the
encrypted message. Note: a ciphertext still contains all of the original message information, even
if it looks nonsense. - Secret key; the same key used for encryption and decryption. -
Cryptography, the science of studying ciphers. For this project, you need to develop a game that
converts normal English words into secret codes. In order to convert, the program randomly
applies an encryption algorithm to any given message. The algorithms you need to implement
include Substitution, Playfais Caesas Transposition, Product, and RSA ciphers. 1. Substitution
cipher, replacing each letter of the alphabet in the plaintext with a different letter in the
ciphertext. For example, if you want to encrypt the word 'Cat', you need to come up with a
substitution for each plaintext letter to a ciphertext letter. For example, you may substitute the
letter ' a ' with the letter ' o '. The rule is that the letter we substitute can only be used once. So,
the letter 'o' is crossed off as it has already been used. The same would be applied to all
alphabetic letters.
1. Substitution cipher; replacing each letter of the alphabet in the plaintext with a different letter
in the ciphertext. For example, if you want to encrypt the word 'Cat'; you need to come up with a
substitution for each plaintext letter to a ciphertext letter, For example. you may substitute the
letter 'a' with the letter ' 0 . The rule is that the letter we substitute can only be used once. So, the
letter 'o' is crossed off as it has already been used. The same would be applied to all alphabetic
letters. You can also substitute a letter with itself. If you are not familiar with this cipher. please
visit: Substitution cipher Page 3 of 5 2. Playfair cipher is a digraph substitution cipher. It
employs a table where one letter of the alphabet is omitted, and the letters are arranged in a 55
grid. For more informat.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Elevating Tactical DDD Patterns Through Object CalisthenicsDorra BARTAGUIZ
After immersing yourself in the blue book and its red counterpart, attending DDD-focused conferences, and applying tactical patterns, you're left with a crucial question: How do I ensure my design is effective? Tactical patterns within Domain-Driven Design (DDD) serve as guiding principles for creating clear and manageable domain models. However, achieving success with these patterns requires additional guidance. Interestingly, we've observed that a set of constraints initially designed for training purposes remarkably aligns with effective pattern implementation, offering a more ‘mechanical’ approach. Let's explore together how Object Calisthenics can elevate the design of your tactical DDD patterns, offering concrete help for those venturing into DDD for the first time!
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
2. Cryptography
Cryptography is the science of writing or reading
coded messages.
Cryptography comes from the Greek words for
“secret writing”
Historically, four groups of people have contributed
to the art of cryptography
The military
The diplomatic corps
The diarists
Of these, the military has had the most important role in this field
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3. Encryption and Decryption
Encryption
The process for producing ciphertext from
plaintext.
Decryption
The reverse Encryption is called Decryption.
Plaintext Plaintext
Ciphertext
Encryption Decryption
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4. Common Cryptography Terms
Plain Text
Original message
The message to be encrypted
Cipher
Secret method of writing (i.e. algorithm)
Key
Plain text is transformed by a function that is parameterized by a key
Some critical information used by the cipher, known only to sender
and/or receiver
Ciphertext
Transformed message
The output of the encryption process
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5. Common Cryptography Terms
Intruder
An enemy who hears and accurately copies down the complete
ciphertext, can be active or passive
Cryptanalysis
Attempting to discover plaintext or key or both
The art of breaking ciphers
Cryptography
Science of secret writing
The art of devising ciphers
Cryptology
Collection of Cryptanalysis and Cryptography
Study of both cryptography and cryptanalysis
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7. Symbolic Notations for Encryption
C = EK(P)
It means that the encryption of the plaintext P using key K
gives ciphertext C
P = DK(C)
It represents the decryption of C to get the plaintext P
again.
It then follows that:
DK( (EK(P)) ) = P
Note:
E and D are just mathematical functions
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8. Two major techniques for encryption
Symmetric Encryption
Sender and receiver use same key (shared secret)
Also known as:
Conventional Encryption
Secret Key Encryption
Was the only method used prior to the 1970s
Still most widely used
Public Key (Asymmetric) Encryption
Sender and receiver use different keys
Technique published in 1976
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10. Conventional Encryption Ingredients
An encryption scheme has five ingredients:
Plaintext
Encryption algorithm
Secret Key
Cipher text
Decryption algorithm
Security depends on the secrecy of the key,
not the secrecy of the algorithm
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11. Strong Encryption
An encryption algorithm needs to be strong
This means that an attacker who knows:
the algorithm
some pieces of ciphertext
some plaintext-ciphertext pairs (possibly)
cannot deduce:
the plaintext, or
the key
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12. Importance of Secret Key
Every encryption and decryption process has two
aspects:
The algorithm
The key used for encryption and decryption
In general, the algorithm used for encryption and
decryption processes is usually known to everybody.
However, it is the key used for encryption and
decryption that makes the process of cryptography
secure
The greater the length of the key, the more difficult
it will be to break it using brute-force attack
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13. Key
A key is a digital code that can be used to encrypt,
decrypt, and sign information.
Some keys are kept private while others are shared
and must be distributed in a secure manner.
The area of key management has seen much progress
in the past years; this is mainly because it makes key
distribution secure and scaleable in an automated
fashion.
Important issues with key management are creating
and distributing the keys securely.
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14. Importance of the Key
Usually, cryptographic mechanisms use both
an algorithm (a mathematical function) and a
secret value known as a key.
Most algorithms undergo years of scrutiny by
the world's best cryptographers who validate
the strength of the algorithm.
The algorithms are widely known and
available; it is the key that is kept secret and
provides the required security.
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15. Importance of the Key
Analogy of Combination Lock
The key is similar to the combination to a lock. Although
the concept of a combination lock is well known, you
can't open a combination lock easily without knowing the
combination.
In addition, the more numbers a given combination has,
the more work must be done to guess the combination---
the same is true for cryptographic keys.
The more bits that are in a key, the less susceptible a key
is to being compromised by a third party.
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16. Issue of Key Length
The number of bits required in a key to ensure secure
encryption in a given environment can be controversial.
The longer the key space---the range of possible values of the
key---the more difficult it is to break the key in a brute-force
attack.
In a brute-force attack, you apply all combinations of a key to
the algorithm until you succeed in deciphering the message.
However, the longer the key, the more computationally
expensive the encryption and decryption process can be.
The goal is to make breaking a key "cost" more than the
worth of the information the key is protecting.
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18. Cryptanalysis
Cryptanalysis is the process of trying to find
the plaintext or key
Two main approaches
Brute Force
try all possible keys
Exploit weaknesses in the algorithm or key
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19. Cryptanalysis: Brute Force Attack
Try all possible keys until code is broken
On average, need to try half of all possible keys
Infeasible if key length is sufficiently long
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20. Three Basic Cryptographic Functions
Cryptography is the basis for all secure
communications; it is, therefore, important that you
understand three basic cryptographic functions:
Symmetric encryption
Asymmetric encryption
One-way hash functions.
Most current authentication, integrity, and
confidentiality technologies are derived from these
three cryptographic functions.
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21. Symmetric Key Encryption
Symmetric encryption, often referred to as secret key
encryption, uses a common key and the same
cryptographic algorithm to scramble and unscramble
a message.
Example: Suppose we have two users, Alice and Bob,
who want to communicate securely with each other.
Both Alice and Bob have to agree on the same
cryptographic algorithm to use for encrypting and
decrypting data.
They also have to agree on a common key--- the secret
key---to use with their chosen encryption/decryption
algorithm.
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22. Symmetric Key Encryption
A simplistic secret key algorithm is the Caesar
Cipher.
The Caesar Cipher replaces each letter in the
original message with the letter of the alphabet n
places further down the alphabet.
The algorithm shifts the letters to the right or left
(depending on whether you are encrypting or
decrypting).
Figure shows two users, Alice and Bob
communicating with a Caesar Cipher where the key,
n, is three letters.
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23. Caesar Cipher
Alphabetic circular shift
For each letter i of text: let pi=0 if letter is a,
and pi=1 if letter is b, etc let key k be the size of the shift
Encryption: ci = Ek(pi) = (pi + k) mod 26
Decryption: pi = Dk(ci) = (ci – k) mod 26
Example (setting k = 3)
attack at dawn
DWWDFN DW GDZQ
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24. Attacking Caesar Cipher
Brute force
Key is just one letter (or number between 1 and
25)
Try all 25 keys
Easy!
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25. Monoalphabetic substitution
Use arbitrary mapping of plaintext letters onto
ciphertext
e.g.
Example:
attack at dawn
XCCXQJ XC MXBF
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26. Attacking Monoalphabetic
Brute force
Very difficult; Key is 26 letters long
No. of possible keys = 26! = 4 x 1026
Algorithm weaknesses:
Frequency of letters in English language is well known
Can deduce plaintext->ciphertext mapping by analysing
frequency of occurrence
e.g. on analysing plenty of ciphertext, most frequent letter
probably corresponds to ‘E’
Can spot digrams and trigrams
Digram: common 2-letter sequence; e.g. ‘th’, ‘an’, ‘ed’
Trigram: common 3-letter sequence: e.g. ‘ing’, ‘the’, ‘est’
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28. Vigenère Cipher
Set of related monoalphabetic substitution rule is used.
“Add” repeating keyword to plaintext
In effect, 26 Caesar ciphers are used
Example:
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30. Attacking Vigenère Cipher
Brute force
More difficult; like password cracking
The longer the key the harder brute force is
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31. One-Time Password
One-time password (OTP) is an encryption
technique that cannot be cracked if used correctly. In
this technique, a plaintext is paired with a random
secret key (also referred to as a one-time password).
Then, each bit or character of the plaintext is
encrypted by combining it with the corresponding bit
or character from the password using modular
addition.
Cipher Text = message + key (mod 26)
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32. One-Time Pads
An OTP is a list of numbers, in completely random
order, that is used to encode a message
If the numbers on OTP are truly random and OTP is
only used once, then ciphertext provides no
mechanism to recover the original key and the
message
OTPs are used for short messages and in a very high
security environment
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33. One-Time Pad
Uses random key that is as long as the
message
Can use key only once One-Time Pad
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35. One-Time Passwords
Problems with OTPs
Generation of truly random one-time passwords
Distribution of the one-time passwords between
communicating entities
Not feasible for use in high-traffic environments
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36. Playfair Cipher
not even the large number of keys in a
monoalphabetic cipher provides security
one approach to improving security was to
encrypt multiple letters
the Playfair Cipher is an example
invented by Charles Wheatstone in 1854, but
named after his friend Baron Playfair
37. Playfair Key Matrix
a 5X5 matrix of letters based on a keyword
fill in letters of keyword (sans duplicates)
fill rest of matrix with other letters
eg. using the keyword MONARCHY
MONAR
CHYBD
EFGIK
LPQST
UVWXZ
38. Encrypting and Decrypting
plaintext encrypted two letters at a time:
1. if a pair is a repeated letter, insert a filler like 'X', eg.
"balloon" encrypts as "ba lx lo on"
2. if both letters fall in the same row, replace each with letter
to right (wrapping back to start from end), eg. “ar"
encrypts as "RM"
3. if both letters fall in the same column, replace each with
the letter below it (again wrapping to top from bottom),
eg. “mu" encrypts to "CM"
4. otherwise each letter is replaced by the one in its row in
the column of the other letter of the pair, eg. “hs" encrypts
to "BP", and “ea" to "IM" or "JM" (as desired)
39. Security of the Playfair Cipher
security much improved over monoalphabetic
since have 26 x 26 = 676 digrams
was widely used for many years (eg. US & British
military in WW1)
it can be broken, given a few hundred letters
since still has much of plaintext structure
40. Rail Fence cipher
write message letters out diagonally over a
number of rows
then read off cipher row by row
eg. write message out as:
m e m a t r h t g p r y
e t e f e t e o a a t
giving ciphertext
MEMATRHTGPRYETEFETEOAAT
41. Column Transposition Ciphers
In a columnar transposition, the message is
written out in rows of a fixed length, and then
read out again column by column
and the columns are chosen in some
scrambled order.
Key: G E R M A N
G E R M A N (326415)
d e f e n d
t h e e a s
t w a l l o
f t h e c a
s t l e x x
G E R M A N d e f e n d t h e e a s t w a l l o f t h e c a s t l e x x
n e d e d f a h t e s e l w t l o a c t f e a h x t s e x l
42. Column Transposition Ciphers
A E G M N R (123456)
n e d e d f
a h t e s e
l w t l o a
c t f e a h
x t s e x l
The ciphertext is read off along the columns:
nalcxehwttdttfseeleedsoaxfeahl
G E R M A N d e f e n d t h e e a s t w a l l o f t h e c a s t l e x x
n e d e d f a h t e s e l w t l o a c t f e a h x t s e x l
The ciphertext is read off along the columns:
nalcxehwttdttfseeleedsoaxfeahl