The document discusses several modes of operation for block ciphers and stream ciphers. It explains that block cipher modes like CBC, CFB, OFB, and Counter Mode require an initialization vector (IV) to provide randomization and prevent identical plaintext blocks from encrypting to the same ciphertext. The IV must be transmitted along with the ciphertext and never reused with the same key. Stream ciphers like RC4 generate a pseudorandom key stream that is XORed with plaintext bytes to produce ciphertext.
this presentation is on block cipher modes which are used for encryption and decryption to any message.That are Defined by the National Institute of Standards and Technology . Block cipher modes of operation are part of symmetric key encryption algorithm.
i hope you may like this.
In cryptography, a block cipher is a deterministic algorithm operating on ... Systems as a means to effectively improve security by combining simple operations such as .... Finally, the cipher should be easily cryptanalyzable, such that it can be ...
Slides for a college cryptography course at CCSF. Instructor: Sam Bowne
Based on: Understanding Cryptography: A Textbook for Students and Practitioners by Christof Paar, Jan Pelzl, and Bart Preneel, ISBN: 3642041000 ASIN: B014P9I39Q
See https://samsclass.info/141/141_F17.shtml
this presentation is on block cipher modes which are used for encryption and decryption to any message.That are Defined by the National Institute of Standards and Technology . Block cipher modes of operation are part of symmetric key encryption algorithm.
i hope you may like this.
In cryptography, a block cipher is a deterministic algorithm operating on ... Systems as a means to effectively improve security by combining simple operations such as .... Finally, the cipher should be easily cryptanalyzable, such that it can be ...
Slides for a college cryptography course at CCSF. Instructor: Sam Bowne
Based on: Understanding Cryptography: A Textbook for Students and Practitioners by Christof Paar, Jan Pelzl, and Bart Preneel, ISBN: 3642041000 ASIN: B014P9I39Q
See https://samsclass.info/141/141_F17.shtml
this is about international data encryption algorithm. this is first ever ppt which includes its history, encryption , figure, decryption and application.. do share ur views after viewing it if u like..
The presentation include:
-Diffie hellman key exchange algorithm
-Primitive roots
-Discrete logarithm and discrete logarithm problem
-Attacks on diffie hellman and their possible solution
-Key distribution center
This material covers Authentication requirement, Authentication function, MAC, Hash function, Security of hash function and MAC, SHA, Digital signature and authentication protocols, DSS, Authentication protocols like Kerberos and X.509, entity authentication
Security+ Guide to Network Security Fundamentals, 3rd Edition, by Mark Ciampa
Knowledge and skills required for Network Administrators and Information Technology professionals to be aware of security vulnerabilities, to implement security measures, to analyze an existing network environment in consideration of known security threats or risks, to defend against attacks or viruses, and to ensure data privacy and integrity. Terminology and procedures for implementation and configuration of security, including access control, authorization, encryption, packet filters, firewalls, and Virtual Private Networks (VPNs).
CNIT 120: Network Security
http://samsclass.info/120/120_S09.shtml#lecture
Policy: http://samsclass.info/policy_use.htm
Many thanks to Sam Bowne for allowing to publish these presentations.
this is about international data encryption algorithm. this is first ever ppt which includes its history, encryption , figure, decryption and application.. do share ur views after viewing it if u like..
The presentation include:
-Diffie hellman key exchange algorithm
-Primitive roots
-Discrete logarithm and discrete logarithm problem
-Attacks on diffie hellman and their possible solution
-Key distribution center
This material covers Authentication requirement, Authentication function, MAC, Hash function, Security of hash function and MAC, SHA, Digital signature and authentication protocols, DSS, Authentication protocols like Kerberos and X.509, entity authentication
Security+ Guide to Network Security Fundamentals, 3rd Edition, by Mark Ciampa
Knowledge and skills required for Network Administrators and Information Technology professionals to be aware of security vulnerabilities, to implement security measures, to analyze an existing network environment in consideration of known security threats or risks, to defend against attacks or viruses, and to ensure data privacy and integrity. Terminology and procedures for implementation and configuration of security, including access control, authorization, encryption, packet filters, firewalls, and Virtual Private Networks (VPNs).
CNIT 120: Network Security
http://samsclass.info/120/120_S09.shtml#lecture
Policy: http://samsclass.info/policy_use.htm
Many thanks to Sam Bowne for allowing to publish these presentations.
A brief discussion of network security and an introduction to cryptography. We end the presentation with a discussion of the RSA algorithm, and show how it works with a basic example.
A lecture at CCSF (updated 8-27-2020)
More info: https://samsclass.info/141/141_F20.shtml
Based on Serious Cryptography: A Practical Introduction to Modern Encryption by Jean-Philippe Aumasson
For a college course -- CNIT 141: Cryptography for Computer Networks, at City College San Francisco
Based on "Serious Cryptography: A Practical Introduction to Modern Encryption", by Jean-Philippe Aumasson, No Starch Press (November 6, 2017), ISBN-10: 1593278268 ISBN-13: 978-1593278267
Instructor: Sam Bowne
More info: https://samsclass.info/141/141_S19.shtml
Modern block ciphers are widely used to provide encryption of quantities of information, and/or a cryptographic checksum to ensure the contents have not been altered. We continue to use block ciphers because they are comparatively fast, and because we know a fair amount about how to design them.
A lecture for a college course -- CNIT 141: Cryptography for Computer Networks, at City College San Francisco
Based on "Serious Cryptography: A Practical Introduction to Modern Encryption", by Jean-Philippe Aumasson, No Starch Press (November 6, 2017), ISBN-10: 1593278268 ISBN-13: 978-1593278267
Instructor: Sam Bowne
More info: https://samsclass.info/141/141_S19.shtml
For a college course at Coastline Community College taught by Sam Bowne. Details at https://samsclass.info/125/125_F17.shtml
Based on: "CISSP Study Guide, Third Edition"; by Eric Conrad, Seth Misenar, Joshua Feldman; ISBN-10: 0128024372
For a college course -- CNIT 141: Cryptography for Computer Networks, at City College San Francisco
Based on "Serious Cryptography: A Practical Introduction to Modern Encryption", by Jean-Philippe Aumasson, No Starch Press (November 6, 2017), ISBN-10: 1593278268 ISBN-13: 978-1593278267
Instructor: Sam Bowne
More info: https://samsclass.info/141/141_S19.shtml
For a college course -- CNIT 141: Cryptography for Computer Networks, at City College San Francisco
Based on "Serious Cryptography: A Practical Introduction to Modern Encryption", by Jean-Philippe Aumasson, No Starch Press (November 6, 2017), ISBN-10: 1593278268 ISBN-13: 978-1593278267
Instructor: Sam Bowne
More info: https://samsclass.info/141/141_S19.shtml
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
2. IV
• All these modes (except ECB) require an initialization vector, or IV --
a sort of 'dummy block' to kick off the process for the first real block,
and also to provide some randomization for the process. There is no
need for the IV to be secret, in most cases, but it is important that it
is never reused with the same key.
• The size of the IV depends on the encryption algorithm and on the
cryptographic protocol in use and is normally as large as the block
size of the cipher or as large as the encryption key
• The IV must be known to the recipient of the encrypted information
to be able to decrypt it. There are a number of ways to ensure that:
by transmitting the IV along with the packet, by agreeing on it
beforehand during the key exchange or the handshake,
3. Cipher modes of operation
• Any block cipher is essentially just a
monoalphabetic substitution cipher using big
characters (on 64 bits)
• �The same plaintext and the same key will
always generate the same ciphertext –this may
be exploited sometimes
• �E.g., this may be exploited to break the header
of a document if we know its structure
• �Five modes of operation (originally for DES,
applicable to any symmetric cipher) have been
defined
• �Describe them briefly in the following
4. Electronic Code Book (ECB) Mode
• This is the simplest way to use the cipher: break
the plaintext into 64-bit blocks and encrypt each
of them with the same key
• The last block should be padded to 64-bit if it is
shorter
• Note: same block and same key always yields
same cipher block
• This can be easily attacked:
• If the message always starts with a predefined
header, then the attacker may have a number of
known plain-cipher pairs
5.
6. Cipher Block Chaining Mode (CBC)
• �Devised to defeat the previous
attack
• �All cipher blocks will be chained
so that if one is modified, the
cipher text cannot be decrypted
correctly (will only produce
“garbage”)
• �Each plaintext block is XORed
with the previous cipher block
before encryption
• �The first plaintext block is
XORed with an initialization vector
IV
• �An initialization vector (IV), also
known as Initialization Value, is a term
in Cryptography. IV is a block of bits
that is combined with the first block of
data in any of several modes of a
block cipher.
7. Cipher Feedback Mode (CFB)
• makes a block cipher into a self-
synchronizing stream cipher. �
• Use a shift register (64 bit for DES, 128 bit for AES, etc)
that is initially set to an initialization vector IV
• Encrypt the content of the register, take leftmost byte of
the cipher and XOR with the current plaintext byte P –the
result C is transmitted, register is left shifted with one
byte and C is placed in the rightmost byte of the register
• Decryption works exactly the same way: note that one
must use the encryption box here
8.
9.
10. Output Feedback Mode (OFB)
(also known as Stream Cipher Mode)
• If affecting 64 bits (for DES, 128 bits for AES) by one
single inverted bit is too much for an application, use
OFB
• Encrypt an IV to get an output block; this block is them
encrypted to get a second block, etc. –this is the key
stream and it will be treated as a one-time pad and
XORed with the plaintext to get the ciphertext
• Key stream is independent of the data and can be
computed in advance
• For decryption generate the same key stream using the
IV and the key
• 1-bit error in the transmission only affects 1-bit in the
ciphertext and in the decryption
11.
12.
13. Counter Mode
• �Files are sometimes kept on computers in encrypted form�
• All modes of operations except ECB make random access to the file
impossible: to access data at the end of the file one has to decrypt
everything�
• Counter Mode fixes this problem
• �Plaintext is not encrypted directly
• �IV plus a constant is encrypted and the resulting ciphertext is
XORed with the plaintext –add 1 to IV in each step
• �Note: if the same IV is used twice with the same key, then
cryptanalyst may XOR the ciphers to get the XOR of the plaintexts –
this could be used in an attack�
– IV must be random!�
– Encryption/decryption in parallel for multiple blocks�
– Simple: decryption algorithm not needed�
– Random access to the file
14.
15. RC5
• Symmetric encryption algorithm developed by Rivest; in (RSA DATA
SECURITY)
• RSA (which stands for Rivest, Shamir and Adleman who first publicly came
up with an encrption algo for public-key cryptography.
• �Characteristics of RC5
– �Suitable for hardware and software: uses only common operations found on
microprocessors
– �Fast: simple and word oriented
– �Adaptable to processors of different word lengths:
– �Variable number of rounds: number of rounds is the 2nd
parameter
– �Variable-length key: key length is the 3rdparameter of RC5
– �Simple: easy to implement and analyze
– �Low memory requirement: suitable for smart cards or other devices with limited
memory
– �High security
– �Data-dependent rotations
16. RC5
• Parameters
– w is the word size in bits –RC5 encrypts blocks of 2 words. Allowed values: 16,
32, 64
– r is the number of rounds. Allowed values: 0,1,…,255
– b is the number of 8-bit bytes in the secret key K. Allowed values: 0,1,…,255
• A specific version of RC5 is denoted RC5-w/r/b
– The author advises to use RC5-32/12/16 as the “nominal” version
– That means: 64-bit plaintext/ciphertext blocks, 12 rounds, 128-bit key
• Algorithm
– Key expansion
– Input manipulation
• �Details are on the following slides:
– where addition and subtraction (+ and -) are modulo 2w
– bitwise XOR is ⊕
– x<<<y is the circular left-shift of x by y bits
– x>>>y is the circular right-shift of word x by y bits
17.
18. RC4 Stream Cipher
• This is the most popular symmetric stream
cipher
• Designed by Rivest for RSA Security
• Used in SSL/TLS (Secure Sockets
Layer/Transport Layer Security) standards for
secure communication between Web browsers
and servers
• Used in WEP, part of the IEEE 802.11 wireless
LAN standard
• RC4 was kept as a trade secret by RSA Inc but
got anonymously posted on the Internet in 1994
19. Stream cipher structure
• �Process the message byte by byte (as a stream)
• �Typically have a (pseudo) random stream key that is
XORed with plaintext bit by bit
• �Randomness of stream key completely destroys any
statistically properties in the message
• �Ci= Mi XOR Stream Key i
• �The simplest encryption/decryption algorithm possible!
• �A stream cipher is similar to the one-time pad
discussed a few lectures back
• ��One must never reuse stream key
– �Otherwise can remove effect and recover messages
– �XOR two ciphertexts obtained with the same key stream to
obtain the XOR of the plaintext.
20.
21. Stream cipher design
• �Key stream should have a large period –a
pseudorandom number generator uses a function that
produces a deterministic (if given the same input
information will always produce the same output )
stream of bits that eventually repeats
• �If treated as a stream of bytes, all 255 values should
occur with the same frequency
• �Key should be long enough to protect against brute-
force attack
• �At least 128 bits
• �Advantage over block ciphers: generating the stream
key is much faster than encrypting and decrypting and
less code is needed
22. RC4 algorithm
• Key length is variable: from 1 to 256 bytes
• Based on the key initialize a 256-byte
state vector S: S[0…255]
• At all times S contains a permutation of
the numbers 0, 1, …, 255
• For encryption and decryption a byte k is
selected from S and the entries in S are
permuted