This document provides an overview of hash algorithms and their uses in cryptography. It begins with definitions of hash functions and their properties like producing a fixed-length output and being one-way. Common hash algorithms are then discussed like MD5, SHA-1, and RIPEMD-160. The document explains the structures and security of these algorithms and analyzes attacks like birthday attacks. It also provides examples of applying hash functions in cryptography.
Module 6
Advanced Networking
Security problems with internet architecture, Introduction to Software defined networking, Working of SDN, SDN in data centre, SDN applications, Data centre networking, IoT.
a message digest is a cryptographic hash function containing a string of digits created by a one-way hashing formula. Message digests are designed to protect the integrity of a piece of data or media to detect changes and alterations to any part of a message. In this paper, we have explained the hashing algorithm of MD5 and also proposed how to use it for file transmission and for hashing any string.
HASH FUNCTIONS AND DIGITAL SIGNATURES
Authentication requirement – Authentication function – MAC – Hash function – Security of hash function and MAC –MD5 – SHA – HMAC – CMAC – Digital signature and authentication protocols – DSS – EI Gamal – Schnorr.
Module 6
Advanced Networking
Security problems with internet architecture, Introduction to Software defined networking, Working of SDN, SDN in data centre, SDN applications, Data centre networking, IoT.
a message digest is a cryptographic hash function containing a string of digits created by a one-way hashing formula. Message digests are designed to protect the integrity of a piece of data or media to detect changes and alterations to any part of a message. In this paper, we have explained the hashing algorithm of MD5 and also proposed how to use it for file transmission and for hashing any string.
HASH FUNCTIONS AND DIGITAL SIGNATURES
Authentication requirement – Authentication function – MAC – Hash function – Security of hash function and MAC –MD5 – SHA – HMAC – CMAC – Digital signature and authentication protocols – DSS – EI Gamal – Schnorr.
Hash Functions, the MD5 Algorithm and the Future (SHA-3)Dylan Field
This was filmed at the Sonoma State University mathematics colloquium on November 5th, 2008. In the talk, Dylan speaks about hash functions, their applications and attacks on them. He specifically focuses on the design of the MD5 algorithm. Dylan also gives a preview of what is in store for the future of hashes- the SHA-3 competition put on by the NIST. For a video of this presentation, visit http://www.vimeo.com/2409021
This PPT explains about the term "Cryptography - Encryption & Decryption". This PPT is for beginners and for intermediate developers who want to learn about Cryptography. I have also explained about the various classes which .Net provides for encryption and decryption and some other terms like "AES" and "DES".
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.
An Enhanced Message Digest Hash Algorithm for Information Securitypaperpublications3
Abstract: Information is an important commodity in the world of Electronic communication. To achieve a secure communication between communicating parties, the protection of authenticity and integrity of information is necessary. Cryptographic hash functions play a central role in cryptology. A cryptographic hash function takes an input of arbitrary large size and returns a small fixed size hash value. It satisfies three major cryptographic properties: preimage resistance, second preimage resistance and collision resistance. Due to its cryptographic properties hash function has become an important cryptographic tool which is used to protect information authenticity and integrity. This thesis presents a review of cryptographic hash functions. The thesis includes various applications of hash functions. It gives special emphasis on dedicated hash functions MD5.
Recent breakthroughs in cryptanalysis of standard hash functions like SHA-1 and MD5 raise the need for alternatives. In the past few years, there have been significant research advances in the analysis of hash functions and it was shown that none of the hash algorithm is secure enough for critical purposes whether it is MD5 or SHA-1. Nowadays scientists have found weaknesses in a number of hash functions, including MD5, SHA and RIPEMD. So the purpose of this thesis is combination of some function to reinforce these functions and also increasing hash code of message digest of length up to 160 that makes stronger algorithm against collision and brute force attacks.
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.
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.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
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/
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.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
• The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
• Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
• Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
• Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
Whether you're a developer, tester, or QA professional, this webinar will give you valuable insights into how AI is shaping the future of software delivery.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
3. Cryptography and Network Security 3
Cryptography and Network
Security
Hash Algorithms
Xiang-Yang Li
4. Cryptography and Network Security 4
Hash Function
Map a message to a smaller value
Requirements
Be applied to a block of data of any size
Produced a fixed length output
H(x) is easy to compute (by hardware, software)
One-way: given code h, it is computationally infeasible
to find x: H(x)=h
Weak collision resistance: given x, computationally
infeasible to find y so H(x)=H(y)
Strong collision resistance: Computationally
infeasible to find x, y so H(x)=H(y)
5. Cryptography and Network Security 5
Hash Algorithms
see similarities in the evolution of hash
functions & block ciphers
increasing power of brute-force attacks
leading to evolution in algorithms
from DES to AES in block ciphers
from MD4 & MD5 to SHA-1 & RIPEMD-160 in hash
algorithms
likewise tend to use common iterative
structure as do block ciphers
6. Cryptography and Network Security 6
Basic Uses of Hash Function
Six basics usages
Ek(M||H(M))
Confidentiality and authentication
M|| Ek(H(M))
Authentication
M|| EKRa(H(M))
Authentication and digital signature
Ek(M|| EKRa(H(M)))
Authentication, digital signature and confidentiality
M||H(M||S)
Authentication (S shared by both sides)
Ek(M||H(M||S))
Confidentiality and authentication
7. Cryptography and Network Security 7
Birthday Attacks
If 64-bits hash code is used
On average, how many messages need to try to find one
match the intercepted hash code?
Birthday paradox
A will sign a message appended with m-bits hash code
Attacker generates some variations of fraud message,
also variations of good message
Find pair of message each from the two sets messages
Such that they have the same hash code
Give good message to A to get signature
Replace good message with fraud message
8. Cryptography and Network Security 8
Analysis
Using birthday attack, given 64-bits hash
code
How many message variations needed so the success
probability is large, say 90%?
9. Cryptography and Network Security 9
Examples
Simple hash functions
XOR of the input message
H(M)=X1 X2 … Xm-1 Xm
But not secure
Ym=H(M) Y1 Y2 … Ym-1 has same hash value as
(X1X2 … Xm-1 Xm), where Yi is any value
10. Cryptography and Network Security 10
Cont.
Based on DES, block chaining technique
Rabin, 1978
Divide message M into fix-sized blocks Mi
Assume total n data blocks
H0=initial value
Hi=Emi[Hi-1]
Hn is the hash value
Birthday attack still applies
If still 64-bits code used
11. Cryptography and Network Security 11
More Attacks
Birthday attack applied if chosen plaintext
Meet in the middle attack if known
plaintext
Known signed hash code G
Construct n-2 desired message block Qi
Compute Hi=EQi[Hi-1]
Generate 2m/2 random blocks X
For each X, Compute Hn-1=EX[Hn-2]
Generate 2m/2 random blocks Y
For each Y, Compute H’n-1=DY[G]
Find X, Y such that Hn-1= H’n-1
Then Q1, Q2,…Qn-2, X,Y is a fraud message
12. Cryptography and Network Security 12
Security
The size of hash code determines security
128bits is not secure
Currently, most use 160 bits hash code
Now recommend 256 bits
Attack MAC
Objective is to find valid (x, Ck(x)) pair
Attack the key space: roughly 2k, k =key size
Attack the MAC value
14. Cryptography and Network Security 14
MD5
designed by Ronald Rivest (the R in RSA)
latest in a series of MD2, MD4
produces a 128-bit hash value
until recently was the most widely used
hash algorithm
in recent times have both brute-force & cryptanalytic
concerns
specified as Internet standard RFC1321
15. Cryptography and Network Security 15
MD5 Overview
1. pad message so its length is 448 mod 512
2. append a 64-bit length value to message
3. initialise 4-word (128-bit) MD buffer
(A,B,C,D)
4. process message in 16-word (512-bit)
blocks:
using 4 rounds of 16 bit operations on message block
& buffer
add output to buffer input to form new buffer value
5. output hash value is the final buffer value
17. Cryptography and Network Security 17
MD5 Compression Function
each round has 16 steps of the form:
a = b+((a+g(b,c,d)+X[k]+T[i])<<<s)
a,b,c,d refer to the 4 words of the buffer,
but used in varying permutations
note this updates 1 word only of the buffer
after 16 steps each word is updated 4 times
where g(b,c,d) is a different nonlinear
function in each round (F,G,H,I)
T[i] is a constant value derived from sin
19. Cryptography and Network Security 19
MD4
precursor to MD5
also produces a 128-bit hash of message
has 3 rounds of 16 steps vs 4 in MD5
design goals:
collision resistant (hard to find collisions)
direct security (no dependence on "hard" problems)
fast, simple, compact
favours little-endian systems (eg PCs)
20. Cryptography and Network Security 20
Strength of MD5
MD5 hash is dependent on all message bits
Rivest claims security is good as can be
known attacks are:
Berson 92 attacked any 1 round using differential
cryptanalysis (but can’t extend)
Boer & Bosselaers 93 found a pseudo collision (again
unable to extend)
Dobbertin 96 created collisions on MD compression
function (but initial constants prevent exploit)
conclusion is that MD5 looks vulnerable
soon
21. Cryptography and Network Security 21
Bad news
Chinese authors (Wang, Feng, Lai, and Yu) reported a
family of collisions in MD5
(fixing the previous bug in their analysis), and also reported
that their method can efficiently (2^40 hash steps) find a
collision in SHA-0.
August Crypto 2004,
MD5 is fatally wounded; its use will be phased out.
SHA-1 is still alive but the vultures are circling. A
gradual transition away from SHA-1 will now start.
The first stage will be a debate about alternatives,
leading to a consensus among practicing
cryptographers about what the substitute will be.
22. On 1 March 2005, Arjen Lenstra, Xiaoyun Wang and Benne
de Weger demonstrated[10] construction of two X.509
certificates with different public keys and the same MD5
hash, a demonstrably practical collision. The construction
included private keys for both public keys.
A few days later, Vlastimil Klima described[11] an improved
algorithm, able to construct MD5 collisions in a few hours on
a single notebook computer.
On 18 March 2006, Klima published an algorithm[12] that can
find a collision within one minute on a single notebook
computer, using a method he calls tunneling.
Cryptography and Network Security 22
23. Cryptography and Network Security 23
Why collisions are bad
An example of what you might do with this.
You could request an SSL certificate (for your real identity)
from a certificate authority. After the response comes back,
you can then use that response (which is based on the MD5
of your identity+key) to "authenticate" a carefully chosen
different certificate, one which claims that you are
LargeBankOrSoftwareCorp., but which has the same MD5 as
your real identity. You can then present this to other people
in order to convince them that you are someone whom you
are not.
Another example,
core internet routers use md5 to exchange passwords. I
simply sniff the md5sum, and if I can find a string that
generates the same sum, easily, I can send my own routing
update that takes down the internet. More examples, since a
LOT of applications use md5, but you get the idea.
24. Cryptography and Network Security 24
Further detail
Obviously the above attack isn't quite so simple, but
this research makes it *possible*. Before, it was
believed to be sufficiently difficult to find a collision,
that nobody worried about it. Now they are saying its
feasible to do it in hours.
The question hanging around right now is that these
researchers managed to find collisions easily, but not
for an artbitrary string. The questions is how long
before someone modifies this method to find any
colllision. That is how much time the world has to
move away.
More at
http://www.freedom-to-tinker.com/archives/000664.html
25. Cryptography and Network Security 25
What to do next
The U.S. National Institute of Standards
and Technology is having a competition for
a new cryptographic hash function.
The phrase "one-way hash function" might
sound arcane and geeky, but hash functions
are the workhorses of modern
cryptography.
Submissions will be due in fall 2008, and a
single standard is scheduled to be chosen
by the end of 2011.
we have an interim solution in SHA-256.
26. Cryptography and Network Security 26
Secure Hash Algorithm (SHA-1)
SHA was designed by NIST & NSA in
1993, revised 1995 as SHA-1
US standard for use with DSA signature
scheme
standard is FIPS 180-1 1995, also Internet RFC3174
nb. the algorithm is SHA, the standard is SHS
produces 160-bit hash values
now the generally preferred hash algorithm
based on design of MD4 with key
differences
27. Cryptography and Network Security 27
SHA Overview
1. pad message so its length is 448 mod 512
2. append a 64-bit length value to message
3. initialise 5-word (160-bit) buffer (A,B,C,D,E)
to
(67452301,efcdab89,98badcfe,10325476,c3d2e1f0)
4. process message in 16-word (512-bit)
chunks:
expand 16 words into 80 words by mixing & shifting
use 4 rounds of 20 bit operations on message block &
buffer
add output to input to form new buffer value
5. output hash value is the final buffer value
28. Cryptography and Network Security 28
SHA-1 Compression Function
each round has 20 steps which replaces the
5 buffer words thus:
(A,B,C,D,E) <-
(E+f(t,B,C,D)+(A<<5)+Wt+Kt),A,(B<<30),C,D)
a,b,c,d refer to the 4 words of the buffer
t is the step number
f(t,B,C,D) is nonlinear function for round
Wt is derived from the message block
Kt is a constant value derived from sin
30. Cryptography and Network Security 30
SHA-1 verses MD5
brute force attack is harder (160 vs 128
bits for MD5)
not vulnerable to any known attacks
(compared to MD4/5)
a little slower than MD5 (80 vs 64 steps)
both designed as simple and compact
optimised for big endian CPU's (vs MD5
which is optimised for little endian CPU’s)
31. Cryptography and Network Security 31
Revised Secure Hash Standard
NIST have issued a revision FIPS 180-2
adds 3 additional hash algorithms
SHA-256, SHA-384, SHA-512
designed for compatibility with increased
security provided by the AES cipher
structure & detail is similar to SHA-1
hence analysis should be similar
33. Cryptography and Network Security 33
RIPEMD-160
RIPEMD-160 was developed in Europe as part of
RIPE project in 96
by researchers involved in attacks on MD4/5
initial proposal strengthen following analysis to
become RIPEMD-160
somewhat similar to MD5/SHA
uses 2 parallel lines of 5 rounds of 16 steps
creates a 160-bit hash value
slower, but probably more secure, than SHA
34. Cryptography and Network Security 34
RIPEMD-160 Overview
1. pad message so its length is 448 mod 512
2. append a 64-bit length value to message
3. initialise 5-word (160-bit) buffer (A,B,C,D,E) to
(67452301,efcdab89,98badcfe,10325476,c3d2e1f0)
4. process message in 16-word (512-bit) chunks:
use 10 rounds of 16 bit operations on message block & buffer –
in 2 parallel lines of 5
add output to input to form new buffer value
5. output hash value is the final buffer value
37. Cryptography and Network Security 37
RIPEMD-160 Design Criteria
use 2 parallel lines of 5 rounds for
increased complexity
for simplicity the 2 lines are very similar
step operation very close to MD5
permutation varies parts of message used
circular shifts designed for best results
38. Cryptography and Network Security 38
RIPEMD-160 verses MD5 & SHA-1
brute force attack harder (160 like SHA-1
vs 128 bits for MD5)
not vulnerable to known attacks, like SHA-1
though stronger (compared to MD4/5)
slower than MD5 (more steps)
all designed as simple and compact
SHA-1 optimised for big endian CPU's vs
RIPEMD-160 & MD5 optimised for little
endian CPU’s
39. Cryptography and Network Security 39
Keyed Hash Functions as MACs
have desire to create a MAC using a hash
function rather than a block cipher
because hash functions are generally faster
not limited by export controls unlike block ciphers
hash includes a key along with the message
original proposal:
KeyedHash = Hash(Key|Message)
some weaknesses were found with this
eventually led to development of HMAC
40. Cryptography and Network Security 40
HMAC
specified as Internet standard RFC2104
uses hash function on the message:
HMACK = Hash[(K+ XOR opad) ||
Hash[(K+ XOR ipad)||M)]]
where K+ is the key padded out to size
and opad, ipad are specified padding constants
overhead is just 3 more hash calculations than the
message needs alone
any of MD5, SHA-1, RIPEMD-160 can be used
42. Cryptography and Network Security 42
HMAC Security
know that the security of HMAC relates to
that of the underlying hash algorithm
attacking HMAC requires either:
brute force attack on key used
birthday attack (but since keyed would need to observe
a very large number of messages)
choose hash function used based on speed
verses security constraints
43. Cryptography and Network Security 43
Summary
have considered:
some current hash algorithms: MD5, SHA-1, RIPEMD-
160
HMAC authentication using hash function