Information and network security 38 birthday attacks and security of hash fun...Vaibhav Khanna
Birthday attack can be used in communication abusage between two or more parties. ... The mathematics behind this problem led to a well-known cryptographic attack called the birthday attack, which uses this probabilistic model to reduce the complexity of cracking a hash function
Information and network security 38 birthday attacks and security of hash fun...Vaibhav Khanna
Birthday attack can be used in communication abusage between two or more parties. ... The mathematics behind this problem led to a well-known cryptographic attack called the birthday attack, which uses this probabilistic model to reduce the complexity of cracking a hash function
Cryptography is the science of using mathematics to encrypt and decrypt data.
Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient.
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
Basic Talk. 90 minute talk to an audience of Freshmen and Sophomores of IIT Bombay on 23/02/10 as a part of Science Week. Organised by Web and Coding Club. Place: GG 101 (Elec Department)
Efficient Coercion Resistant Public Key EncryptionCSCJournals
The notion of deniable encryption has been known in the literature since its introduction in [1] as coercion resistant encryption schemes that allow the user (sender and/or receiver) to escape a coercion attempted by a coercive adversary. The schemes allow the user to open fake message(s) to the coercer that when verified gives the same ciphertext as the true message, while the receiver is always able to decrypt for the true message. In this paper we focus on sender-incoercible encryption. The contribution of this paper is two-fold. First, we introduce a new classification of services that could be provided by coercion-resistant encryption showing that all previously proposed deniable PKE schemes fall in the category of unplanned incoercible PKE assuming the user is non-collaborative and do not satisfy the requirements for deniable encryption. Then we inspect, refine and improve the sender-incoercible PKE introduced in [2]. Our new scheme achieves constant transmission rate where the size of the plaintext may be calibrated to be sufficiently large i.e. the scheme encrypts arbitrary length messages without a blowup expansion in the ciphertext while the size of the ciphertext grows linearly with the number of fake messages.
Cryptography is the science of using mathematics to encrypt and decrypt data.
Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient.
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
Basic Talk. 90 minute talk to an audience of Freshmen and Sophomores of IIT Bombay on 23/02/10 as a part of Science Week. Organised by Web and Coding Club. Place: GG 101 (Elec Department)
Efficient Coercion Resistant Public Key EncryptionCSCJournals
The notion of deniable encryption has been known in the literature since its introduction in [1] as coercion resistant encryption schemes that allow the user (sender and/or receiver) to escape a coercion attempted by a coercive adversary. The schemes allow the user to open fake message(s) to the coercer that when verified gives the same ciphertext as the true message, while the receiver is always able to decrypt for the true message. In this paper we focus on sender-incoercible encryption. The contribution of this paper is two-fold. First, we introduce a new classification of services that could be provided by coercion-resistant encryption showing that all previously proposed deniable PKE schemes fall in the category of unplanned incoercible PKE assuming the user is non-collaborative and do not satisfy the requirements for deniable encryption. Then we inspect, refine and improve the sender-incoercible PKE introduced in [2]. Our new scheme achieves constant transmission rate where the size of the plaintext may be calibrated to be sufficiently large i.e. the scheme encrypts arbitrary length messages without a blowup expansion in the ciphertext while the size of the ciphertext grows linearly with the number of fake messages.
Our wish here is to present some functional components, which are essential to the implementation of cryptographic protocols, such as those underlying the BlockChain.
BeeBryte - Energy Intelligence & Automation
www.beebryte.com
Our wish here is to present some functional components, which are essential to the implementation of cryptographic protocols, such as those underlying the BlockChain.
BeeBryte - Energy Intelligence & Automation
www.beebryte.com
Answer die following questions with short answers Explain the d.pdfcalderoncasto9163
Answer die following questions with short answers: Explain the difference between stream
ciphers and block cipher. Explain the difference between passive and active attacks. Describe
the difference between authentication and non-repudiation Explain the difference between a
MAC and message digest. Give one advantage and one disadvantage of public-key cryptography
over symmetric-key cryptogra Why is CBC mode considered preferable to ECB mode?
Solution
a)
stream cipher and block cipher differ in whitch the plain text is encoded and decoded.
the basic difference is how the logic used for the encryption and decryption. the idea of block
cipher is partition the plain text into relatively larger blocks and further each block will be
encoded.
and same key is used for both encryption and decryption.example DES,IDEA
the idea of stream cipher is plain text is encrypted and transfered bit by bit.but key property of
stream cipher is different key is generated for each block or bit.example -ISAAC,FISH
b)
passive attack is indirect attack.the attacked host is completely unaware about the attack.
hence it is called passive attack like some body listens the packet transformation or observing
the host in network.
active attack is direct attack.its nothing but the attacked one gets aware of the attack.
like somebody listens the id and password and stop the services(denial of service) or logic
bomb.
both are harmful.
c)
authentication and non repudiation are two different things.
authentication verifies the who you are(user-id).where the non-repudiation verifies the what you
did(messages).
authentication is done through a central instance where non repudiation can done by anyone
d)
message digest is a hash of a message.its output of a cryptographic hash function appilied to
input data it refered to as message.
mac is a piece of information that proves the integrity of a message.
message digest is take only single input and produces a message digest(aka hash) if the message
change it produce different hash code.
mac (message authentication code) is take input and security code to check the integrity of
message. HMAC is one of this kind.
e)
advantage of public key cryptography over the symmetric key cryptography is increased
security and convenience.
and no need of key distribution(transmitted to anyone).and it provide digital signatures that
cannot be repudiated.
the disadvantage of public key cryptography over symmetric cryptography is speed.they are
many symmetic key methods runs faster than the public key cryptography.
f)
the reason why cbc is considered better than ecb has nothing to do with situations involving
an attacker with partial cipher text.
problem with ECB is that it leaks the information like when two blocks have same plain text
then the corresponding cipher blocks also be same where in case
of the CBC it randomly independent of plain text to produce the cipher text..
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
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Toxic effects of heavy metals : Lead and Arsenicsanjana502982
Heavy metals are naturally occuring metallic chemical elements that have relatively high density, and are toxic at even low concentrations. All toxic metals are termed as heavy metals irrespective of their atomic mass and density, eg. arsenic, lead, mercury, cadmium, thallium, chromium, etc.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
Phenomics assisted breeding in crop improvementIshaGoswami9
As the population is increasing and will reach about 9 billion upto 2050. Also due to climate change, it is difficult to meet the food requirement of such a large population. Facing the challenges presented by resource shortages, climate
change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
and analysis methods, numerous infrastructure platforms have been developed for phenotyping.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
2. Passive attacks are in the nature of eavesdropping on, or
monitoring of, transmissions.
The goal of the opponent is to obtain information that is
being transmitted.
Two types of passive attacks are the release of message
contents and traffic analysis.
Active attacks involve some modification of the data stream
or the creation of a false stream and can be subdivided into
four categories: masquerade, replay, modification
of messages, and denial of service.
2
3. Differential cryptanalysis is a general form of
cryptanalysis applicable primarily to block ciphers, but
also to stream ciphers and cryptographic hash functions.
Differential attack is a chosen-plaintext attack .
can successfully cryptanalyze DES with an effort on the
order of
The main difference from linear attack is that
differential attack involves comparing the XOR of two
inputs to the XOR of the corresponding outputs .
This difference provide information that can be used to
determine the key .
4. 4
linear cryptanalysis is a general form of cryptanalysis
based on finding affine approximations to the action of
a cipher Attacks have been developed for block ciphers
and stream ciphers. Linear cryptanalysis is one of the
two most widely used attacks on block ciphers
Linear Cryptanalysis is (known plaintext attack).
This method can find a DES key given known
plaintexts .
Although this is a minor improvement, because it
may be easier to acquire known plaintext rather than
chosen plaintext, it still leaves linear cryptanalysis
infeasible
5. Meet-in-the-middle attack is performed on two blocks of
known ( plaintext–ciphertext ) , the probability that the correct
keys are determined .
The meet-in-the-middle attack targets block cipher cryptographic
functions ( double DES ) .
The name for this exploit comes from the method. Because the
attacker tries to break the two-part encryption method from
both sides , a successful effort enables him to meet in the middle
of the block cipher.
Meet-in-the-middle is a passive attack, which means that
although the intruder can access messages, in most situations he
can not alter them or send his own.
6. is an attack where the attacker secretly relays and
possibly alters the communication between two parties
who believe they are directly communicating with each
other. A man-in-the-middle attack can be used against
many cryptographic protocols. One example of man-in-
the-middle attacks is active eavesdropping, in which the
attacker makes independent connections with the victims
and relays messages between them to make them believe
they are talking directly to each other over a private
connection, when in fact the entire conversation is
controlled by the attacker. The attacker must be able to
intercept all relevant messages passing between the two
victims and inject new ones. This is straightforward in
many circumstances;
6
8. Alice sends a message to Bob, which is intercepted by Mallory:
Alice "Hi Bob, it's Alice. Give me your key.“ → Mallory Bob
Mallory relays this message to Bob; Bob cannot tell it is not really from
Alice: Alice Mallory "Hi Bob, it's Alice. Give me your key." → Bob
Bob responds with his encryption key:
Alice Mallory ← [Bob's key] Bob
Mallory replaces Bob's key with her own, and relays this to Alice, claiming
that it is Bob's key: Alice ← [Mallory's key] Mallory Bob
Alice encrypts a message with what she believes to be Bob's key, thinking
that only Bob can read it:
Alice "Meet me at the bus stop!" [encrypted with Mallory's key]
→ Mallory Bob
However, because it was actually encrypted with Mallory's key, Mallory can
decrypt it, read it, modify it (if desired), re-encrypt with Bob's key, and
forward it to Bob :
Alice Mallory "Meet me at the van down by the river!" [encrypted with
Bob's key] → Bob
Bob thinks that this message is a secure communication from Alice.
Bob goes to the van down by the river and gets robbed by Mallory . 8
9. Brute-Force attack
A brute-force attack does not depend on the specific algorithm
but depends only on bit length of the hash value .
A cryptanalysis, in contrast, is an attack based on weaknesses in a
particular cryptographic algorithm.
PREIMAGE AND SECOND PREIMAGE ATTACKS
For a preimage or second preimage attack, an adversary wishes to
find a value such that H(y) is equal to a given hash value .The
brute-force method is to pick values of at random and try each
value until a collision occurs. For an -bit hash value, the level of
effort is proportional to Specifically, the adversary would have to
try, on average, values of y to find one that generates a given hash
value .
10. COLLISION RESISTANT ATTACKS
For a collision resistant attack, an adversary wishes to find two
messages or data blocks , x and , y that yield the same hash
function: . This turns out to require considerably less effort than a
preimage or second preimage attack. if we pick data blocks at
random, we can expect to find two data blocks with the same hash
value within attempts.
11. As with encryption algorithms, cryptanalytic attacks on hash
functions seek to exploit some property of the algorithm to perform
some attack other than an exhaustive search. The way to measure
the resistance of a hash algorithm to cryptanalysis is to compare its
strength to the effort required for a brute-force attack. That is, an
ideal hash algorithm will require a cryptanalytic effort greater than
or equal to the brute-force effort.
Cryptanalysis of hash functions focuses on the internal structure
of f and is based on attempts to find efficient techniques for
producing collisions for a single execution of f.
f consists of a series of rounds of processing, so that the attack
involves analysis of the pattern of bit changes from round to
round..
12. a timing attack is one in which information about the key or the plaintext
is obtained by observing how long it takes a given implementation to
perform decryptions on various cipher texts . A timing attack exploits the
fact that an encryption or decryption algorithm often takes slightly different
amounts of time on different inputs.
Timing attacks are applicable not just to RSA, but to other public-key
cryptography systems. This attack is alarming for two reasons: It comes from
a completely unexpected direction, and it is a ciphertext-only attack.
A timing attack guessing the combination of a safe by observing how long it
takes for someone to turn the dial from number to number.
Although the timing atta`ck is a serious threat, there are simple
countermeasures that can be used, including the following : ( fix or resistant )
• Constant exponentiation time: Ensure that all exponentiations take the
same amount of time before returning a result .
• Random delay: Better performance could be achieved by adding a random
delay to the exponentiation algorithm to confuse the timing attack.
• Blinding: Multiply the ciphertext by a random number before performing
Exponentiation .This process prevents the attacker from knowing what
ciphertext bits are being processed inside the computer and therefore
prevents the bit-by-bit analysis essential to the timing attack.
13. A brute-force attack on a MAC is a more difficult undertaking
than a brute-force attack on a hash function because it
requires known message-tag pairs.
The attacker would like to come up with the valid MAC code
for a given message, There are two lines of attack possible:
attack the key space and attack the MAC value .
If an attacker can determine the MAC key, then it is possible to
generate a valid MAC value for any input x .
At least one key is guaranteed to produce the correct tag,
namely, the valid key that was initially used to produce the
known text–tag pair.
the objective is to generate a valid tag for a given message or to
find a message that matches a given tag
14. As with encryption algorithms and hash functions,
cryptanalytic attacks on MAC algorithms seek to exploit
some property of the algorithm to perform some attack
other than an exhaustive search .
The way to measure the resistance of a MAC algorithm
to cryptanalysis is to compare its strength to the effort
required for a brute-force attack. That is, an ideal MAC
algorithm will require a cryptanalytic effort greater than
or equal to the brute-force effort , There is much more
variety in the structure of MACs than in hash functions,
15. might think a 64-bit hash is secure
birthday attack works thus:
given user prepared to sign a valid message x
opponent generates 2m/2 variations x’ of x,
all with essentially the same meaning, and
saves them
opponent generates 2m/2 variations y’ of a
desired fraudulent message y
two sets of messages are compared to find
pair with same hash (probability > 0.5 by
birthday paradox)
have user sign the valid message, then
substitute the forgery which will have a valid
signature
conclusion is that need to use larger MAC/hash
15
16. Square Attack was first proposed by Daemenetal. in as a
dedicated attack on block cipher SQUARE, a forerunner
of AES. It was shown to be applicable to AES as well.
This attack consists of choosing a special set of plaintexts
and studying its propagation through the block cipher.
The attack on AES is illustrated as follows:
Consider a set of 28 plaintexts in which the first byte
takes all possible 256 values and the remaining bytes take
any constant value that remains same throughout the set.
We call such a set of plaintexts as -set. The byte which
takes all possible 256 values is termed as the active byte.
Rest of the bytes are termed as passive bytes.
16
17. Key-only attack: attacker only knows user’s public key.
Known message attack: attacker is given access to a set of messages
and their signatures.
Generic chosen message attack: attacker chooses a list of messages
before attempting to breaks user’s signature scheme, independent of user’s
public key. The attacker then obtains from a user valid signatures for the
chosen messages . The attack is generic, because it does not depend on
user’s public key; the same attack is used against everyone.
Directed chosen message attack: Similar to the generic attack, except
that the list of messages to be signed is chosen after the attacker knows
user’s public key but before any signatures are seen.
Adaptive chosen message attack: attacker is allowed to use user as an
“oracle.” This means the user may request signatures of messages that
depend on previously obtained message–signature pairs.
18. 18
attackAlgorithm
Brute force , Mathematical attacks , Timing
attacks , Chosen ciphertext attacks
RSA
Differential and linear cryptanalysisDES
Meet-in-the -middle attackDouble DES
Man-in-the-Middle AttackDiffie-Hellman
Brute-Force attack , CryptanalysisHash function
Brute-Force attack , CryptanalysisMac
Key-only attack , Known message attack , Generic
chosen message attack , Directed chosen message
attack , Adaptive chosen message attack
Digital signature
Known-Plaintext AttackTriple DES
19. Finding the relationship between two
quantitative variables without being able
to infer causal relationships
Correlation is a statistical technique used to
determine the degree to which two
variables are related
19
20. Regression: technique concerned with
predicting some variables by knowing
others
The process of predicting variable Y using
variable X
Uses a variable (x) to predict some
outcome variable (y)
Tells you how values in y change as a
function of changes in values of x
20