The document describes Freenet, a distributed anonymous information storage and retrieval system. Freenet operates as a decentralized peer-to-peer network where nodes can store and retrieve data. It aims to protect anonymity of users and resist censorship of information. Data is stored on the network through a process where requests are routed across nodes based on the data key. This allows for popular data to be replicated across nodes.
We all use Wifi today. You know how much money it saves for your smart-phone data usage band-width. Connecting all your computers and gadgets with cables is not just history, even if you attempt it would be impractical!
Wifi being so pervasive, also brings along tremendous security implications. Come join us to look into details of Wifi security. How to secure your wifi network? How certain wifi encryption technologies can be hacked? We would prove that with live demos!
Join us to reflect on the security aspect of this technology, discuss about it and leave with more confidence about how 'secure' your WiFi access is?
We all use Wifi today. You know how much money it saves for your smart-phone data usage band-width. Connecting all your computers and gadgets with cables is not just history, even if you attempt it would be impractical!
Wifi being so pervasive, also brings along tremendous security implications. Come join us to look into details of Wifi security. How to secure your wifi network? How certain wifi encryption technologies can be hacked? We would prove that with live demos!
Join us to reflect on the security aspect of this technology, discuss about it and leave with more confidence about how 'secure' your WiFi access is?
Daknet Abstract ( prepared by me for seminar in my college )Nikhil Jain
DakNet is an ad hoc network which uses wireless technology to provide digital connectivity.
A simple store-and-forward WiFi system, using a government bus as a central linkage. The bus contains a simple WiFi installation and server, and when in range of one of the outlying information kiosks it synchronizes data for later processing. Mounted and powered on a bus or motorcycle with a small generator MAP physically transports data between public kiosks and private communications devices and between kiosks and a hub (for non real time internet access). Low cost Wi-Fi radio transceivers transfer data stored in MAP at high bandwidth for each point-to-point connection.
GI-FI (Gigabit Fidelity) or Giga bit wireless refers to wireless communication at a data rate of more than one billion bits (gigabits) per second. GI-FI offers some advantages over WI-FI, a similar wireless technology. In that it offers faster information rate in GBPS, less power consumption and low cost for short range transmission as compare to current technology. GI-FI consists of a chip which has facility to deliver short-range multi gigabit data transfer in a local environment and compared to other technologies in the market it is ten times faster. GI-FI has the data transfer speed up to 5 GBPS within a short-range of 10 metres. It operates in 60 GHZ frequency band. GI-FI is developed on an integrated wireless transceiver chip. It has both transmitter and receiver, integrated on a single chip which is fabricated using the CMOS (complementary metal oxide semiconductor) process and it also consists of a small antenna. GI-FI allows transferring large videos, audio files, data files etc. within few seconds.
gi-fi :the next generation wireless technologyHarshad Kale
Gigabit Wireless is the world‟s first transceiver integrated on a single chip which operates at 60GHz
on the CMOS process. Wireless transfer of large files, audio and video data upto
5 gigabits per second is
possible with this chip. The cost of wireless transfer rate is one
-
tenth and it provides ten times faster speed
within a range of 10 meters. It uses a 5mm square chip and a 1mm wide antenna burning less than 2milli
w
atts of power to transmit data wirelessly over short distances, similar to Bluetooth. Gi
-
Fi technology
provides
various different features like
High speed of data transfer, Low power consumption, High security,
Cost effective, Small size, Quick
deployment, Highly portable, high mobility etc.
A Pilot study on issues and complexity of digital forensics and how digital forensics can be applied in a live environment without the loss or spoilage of valuable data and evidence
In the last few decades, Mobile Wireless Communication networks have experienced a remarkable change. The mobile wireless Generation (G) generally refers to a change in the nature of the system, speed, technology, frequency, data capacity, latency etc.
↓↓↓↓ Read More:
@ Kindly Follow my Instagram Page to discuss about your mental health problems-
-----> https://instagram.com/mentality_streak?utm_medium=copy_link
@ Appreciate my work:
-----> behance.net/burhanahmed1
Thank-you !
Freenet: The technical part of the solution for Freedom of the Press in the I...Arne Babenhauserheide
In 2000 we said that the internet is at a crossroad between surveillance and freedom. Freenet started to fight for ensuring freedom of the press. Then 9/11 happened. In 2013 Edward Snowden made the general public realize that we are already far past that crossroad. He gave us precious time to turn back the wheel and take the road towards freedom.
Daknet Abstract ( prepared by me for seminar in my college )Nikhil Jain
DakNet is an ad hoc network which uses wireless technology to provide digital connectivity.
A simple store-and-forward WiFi system, using a government bus as a central linkage. The bus contains a simple WiFi installation and server, and when in range of one of the outlying information kiosks it synchronizes data for later processing. Mounted and powered on a bus or motorcycle with a small generator MAP physically transports data between public kiosks and private communications devices and between kiosks and a hub (for non real time internet access). Low cost Wi-Fi radio transceivers transfer data stored in MAP at high bandwidth for each point-to-point connection.
GI-FI (Gigabit Fidelity) or Giga bit wireless refers to wireless communication at a data rate of more than one billion bits (gigabits) per second. GI-FI offers some advantages over WI-FI, a similar wireless technology. In that it offers faster information rate in GBPS, less power consumption and low cost for short range transmission as compare to current technology. GI-FI consists of a chip which has facility to deliver short-range multi gigabit data transfer in a local environment and compared to other technologies in the market it is ten times faster. GI-FI has the data transfer speed up to 5 GBPS within a short-range of 10 metres. It operates in 60 GHZ frequency band. GI-FI is developed on an integrated wireless transceiver chip. It has both transmitter and receiver, integrated on a single chip which is fabricated using the CMOS (complementary metal oxide semiconductor) process and it also consists of a small antenna. GI-FI allows transferring large videos, audio files, data files etc. within few seconds.
gi-fi :the next generation wireless technologyHarshad Kale
Gigabit Wireless is the world‟s first transceiver integrated on a single chip which operates at 60GHz
on the CMOS process. Wireless transfer of large files, audio and video data upto
5 gigabits per second is
possible with this chip. The cost of wireless transfer rate is one
-
tenth and it provides ten times faster speed
within a range of 10 meters. It uses a 5mm square chip and a 1mm wide antenna burning less than 2milli
w
atts of power to transmit data wirelessly over short distances, similar to Bluetooth. Gi
-
Fi technology
provides
various different features like
High speed of data transfer, Low power consumption, High security,
Cost effective, Small size, Quick
deployment, Highly portable, high mobility etc.
A Pilot study on issues and complexity of digital forensics and how digital forensics can be applied in a live environment without the loss or spoilage of valuable data and evidence
In the last few decades, Mobile Wireless Communication networks have experienced a remarkable change. The mobile wireless Generation (G) generally refers to a change in the nature of the system, speed, technology, frequency, data capacity, latency etc.
↓↓↓↓ Read More:
@ Kindly Follow my Instagram Page to discuss about your mental health problems-
-----> https://instagram.com/mentality_streak?utm_medium=copy_link
@ Appreciate my work:
-----> behance.net/burhanahmed1
Thank-you !
Freenet: The technical part of the solution for Freedom of the Press in the I...Arne Babenhauserheide
In 2000 we said that the internet is at a crossroad between surveillance and freedom. Freenet started to fight for ensuring freedom of the press. Then 9/11 happened. In 2013 Edward Snowden made the general public realize that we are already far past that crossroad. He gave us precious time to turn back the wheel and take the road towards freedom.
Want similar presentation ideas? Interact and follow me in Quora : https://www.quora.com/profile/Liju-Thomas-13 or
Connect with me through Facebook : http://www.facebook.com
/lijuthomas24
Researchers have always tried to build a device capable of seeing people through walls. However, previous efforts to develop such a system have involved the use of expensive and bulky radar technology that uses a part of the electromagnetic spectrum only available to the military. Now a system is being developed by Dina Katabi and Fadel Adib, could give all of us the ability to spot people in different rooms using low-cost Wi-Fi technology. The device is low-power, portable and simple enough for anyone to use, to give people the ability to see through walls and closed doors. The system, called “Wi-Vi,” stands for "Wi-Fi" and "vision." is based on a concept similar to radar and sonar imaging. But in contrast to radar and sonar, it transmits a low-power Wi-Fi signal and uses its reflections to track moving humans. It can do so even if the humans are in closed rooms or hiding behind a wall.
Simple definition for Wi-Vi is, as a Wi-Fi signal is transmitted at a wall, a portion of the signal penetrates through it, reflecting off any humans on the other side. However, only a tiny fraction of the signal makes it through to the other room, with the rest being reflected by the wall, or by other objects. Wi-Vi cancels out all these other reflections, and keeps only those from the moving human body. Previous work demonstrated that the subtle reflections of wireless inter signals bouncing off a human could be used to track that person's movements, but those previous experiments either required that a wireless router was already in the room of the person being tracked. Wi-Fi signals and recent advances in MIMO communications are used to build a device that can capture the motion of humans behind a wall and in closed rooms. Law enforcement personnel can use the device to avoid walking into an ambush, and minimize casualties in standoffs and hostage situations. Emergency responders can use it to see through rubble and collapsed structures. Ordinary users can leverage the device for gaming, intrusion detection, privacy-enhanced monitoring of children and elderly, or personal security when stepping into dark alleys and unknown places.
The concept underlying seeing through opaque obstacles is similar to radar and sonar imaging. Specifically, when faced with a non-metallic wall, a fraction of the RF signal would traverse the wall, reflect off objects and humans, and come back imprinted with a signature of what is inside a closed room. By capturing these reflections, we can image objects behind a wall.
Wi-Vi is a see-through-wall technology that is low-bandwidth, low-power, compact, and accessible to non-military entities. Wi-Vi is a see-through-wall device that employs Wi-Fi signals in the 2.4 GHz ISM band.
This is a power-point about Networking and Resource Sharing in Library and Information Services: the case study of Consortium Building
Prepared By: May Joyce M. Dulnuan
A series of screenshots of a WattzOn kiosk that is coming together now -- part of that kiosk is a "whole earth simulator" to let people play with variables like the energy mix to understand how those effect the world at large.
Building Secure Open & Distributed Social NetworksHenry Story
How to Build Open Distributed Social Networks with no central point of control. Displays an OpenSource application that can browse and edit that network. Shows how it works, how it can do simple firewall based security. It then looks at how to add fine grained security in such a network that would be equivalent to Social Networking applications such as LinkedIn or Facebook.
A short tutorial on R, basically for a starter who wants to do data mining especially text data mining.
Related codes and data will be found at the following lnik: http://textanalytics.in/wm/R%20tutorial%20(DATA2014).zip
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
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.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Francesca Gottschalk - How can education support child empowerment.pptx
Freenet
1. Anonymous Information
Storage and Retrieval System
Ashraf Uddin
Sujit Singh
South Asian University
(Master of Computer Application)
http://ashrafsau.blogspot.in/
http://ashrafsau.blogspot.in/
2. Introduction
Networked Computer Systems are rapidly
growing.
Current systems offer little user privacy.
Every new data item stored in only one or
few places.
http://ashrafsau.blogspot.in/
3. Freenet
A distributed information storage and retrieval
system.
Privacy concerns.
No central point failures.
Operates as a distributed file system across
many individual computers.
Transparent moving, deleting, replication of data
http://ashrafsau.blogspot.in/
4. Freenet Design Goals
Anonymity for producer and consumer of
information.
Deniability for storers of information.
Resistance to attempts by third parties to deny
access to information.
Efficient Dynamic storage and routing of
information.
Network functions decentralization.
http://ashrafsau.blogspot.in/
5. Roadmap
Architecture
Keys and Searching
Retrieving Data
Storing Data
Managing Data
Adding Nodes
Protocol Details
Performance Analysis
Network Convergence
Scalability
Fault Tolerance
Small World Model
Security
http://ashrafsau.blogspot.in/
6. Architecture ( 1 / 2)
Freenet implemented as an adaptive peer to
peer network of nodes.
Nodes can query each other for information
store or retrieval.
Files named after location independent keys.
Each node maintains :
Shared Datastore
Routing Table of entries ( node address, possible
data keys ).
http://ashrafsau.blogspot.in/
7. Architecture ( 2 / 2)
Requests for keys are passed along from node
to node through a chain of proxy requests.
Routes depend on the key.
Each request is assigned a hops-to-live value.
Each request is assigned a pseudo-unique
random identifier.
Joining to the network requires address
discovering of some nodes.
http://ashrafsau.blogspot.in/
8. Keys And Searching
Freenet data files are identified by binary
file keys.
Binary file keys obtained by 160bit SHA-
1.
Three Types of keys
1. Keyword-Signed Key (KSK)
2. Signed-Subspace Key ( SSK )
3. Content Hash Key ( CHK )
http://ashrafsau.blogspot.in/
9. Keyword-Signed Key (KSK) ( ½)
KSK derived from a descriptive string of the file.
The descriptive string is chosen when storing the
file.
Based on the descriptive string a public/private
key pair is generated.
Public half is hashed to yield the file key.
Private half ensures the match of a retrieved file
– sign of the file.
http://ashrafsau.blogspot.in/
10. Keyword-Signed Key (KSK) (2/2)
The user publishes only the descriptive
string.
Problem : Global namespace. Collisions,
junk file under popular descriptive strings.
The file is encrypted using the descriptive
string as a key.
http://ashrafsau.blogspot.in/
12. Signed-Subspace Key ( SSK ) (1/2)
Attacks global namespace problems.
A user creates a namespace by randomly
generating a public/private key pair.
File insertion based on the private half.
File key generation process
1. Public namespace key and descriptive string
hashed independently
2. XOR’ed together
3. Hash the XOR result.
http://ashrafsau.blogspot.in/
13. Signed-Subspace Key ( SSK ) (2/2)
Private half used to sign the file.
User publishes the descriptive string along
with the subspace’s public key.
Storing/Adding/Updating data requires the
private key.
The file is encrypted using the descriptive
string as a key.
http://ashrafsau.blogspot.in/
15. Content Hash Key ( CHK )
A content hash key is acquired by directly
hashing the contents of the corresponding file.
This assigns a pseudo unique file key.
Files are encrypted using a randomly generated
hash key.
User publishes the content hash key along with
the decryption key.
The decryption key is not stored together with
the file.
http://ashrafsau.blogspot.in/
18. Retrieving Data (1/3)
Downstream node : Node to which a request will
be passed.
Upstream node : Node to which a reply/data
returns.
Process of retrieving data
User initiates a request of the form ( binary file key,
hops-to-live)
The request is send to “his” node.
If found the data is returned with a note indicating
who was the source
http://ashrafsau.blogspot.in/
19. Retrieving Data (2/3)
Continued
If not found, the request is propagated to the next node.
If found in the next node, the data is returned back across the
path established. Data cached on every intervening node.
New route entries are created.
Failures
If downstream node “down”, current node tries it’s second
choice.
If hops-to-live exceeded, failure message returned to the original
requestor.
http://ashrafsau.blogspot.in/
20. Retrieving Data (3/3)
**a request operates as a steepest-ascent
hill-climbing search with backtracking.
http://ashrafsau.blogspot.in/
21. 1. A initiates
A request and asks F
B if it has file
2. B doesn’t so it
12. B sends file asks best-bet peer =
F 3. F doesn’t either and no more nodes to
back to A
ask so returns “request failed” message
B
7. B now detects that it has 4. B tries its second choice D
seen this request before so
returns a “request failed”
message E
11. File sent to B File is Here!
9. D now tries its
second choice E
6. Nor C so forwards request
to B 10. Success!! E
then returns file
back to D who
5. D doesn’t have it so forwards request to C
propagates it
C D back to A
8. C forwards “request failed back to D
http://ashrafsau.blogspot.in/
24. Effects of the data retrieve process
After some “queries” nodes will specialize in few
sets of similar keys. – Similar :
Lexicographically.
Nodes will specialize in storing clusters of files
with similar keys.
Popular data will be transparently replicated
near the “requesting” nodes.
As nodes process requests, new route entries
are created – Connectivity increased.
http://ashrafsau.blogspot.in/
25. Lexicographic closeness = Data
closeness ?
Lexicographic closeness does not imply
descriptive string closeness.
E.g Hash keys AH5JK2, AH5JK3, AH5JK5
will most probably refer to completely
unrelated files.
This scattering was actually intended in
order to attach central points of failures.
http://ashrafsau.blogspot.in/
26. Storing Data ( 1/ 2)
Storing data is similar to the process of retreving
data.
Calculate the binary file key, specify hops-to-live.
Hops-to-live specifies the number of nodes
where the data will be stored.
Nodes accept insert proposals.
If the key is found, the node returns the pre-
existing file to the requestor.
http://ashrafsau.blogspot.in/
27. Storing Data ( 2/ 2)
If key not found, the node propagates the
request to the next route based on key
lexicographic distances.
When hops-to-live reached, a ‘all clear message’
is sent to the original requestor.
The requestor then sends the data to be stored.
This data is cached on every node along the
established path. Also route entries are created.
Same case of failure as with the retrieve
process.
http://ashrafsau.blogspot.in/
29. Effects of the storing Mechanism
1. New files are cached on nodes that have
already stored files with similar keys.
2. Newly added nodes can use the store
mechanism to announce their existence.
3. Attackers that may try to insert junk files
under existing keys will simply spread
the pre-existing files.
http://ashrafsau.blogspot.in/
30. Data Management ( ½)
Finite storage space.
Finite route table space.
Storage managed by LRU.
When a new files comes to be stored and no
space available – LRU entries deleted.
Inconsistency between Storage space and route
tables.
Routing table entries are deleted in the same
fashion.
http://ashrafsau.blogspot.in/
31. Data Management (2/2)
No guarantee for file lifetime.
Nodes can decide to completely drop a
data file.
Encryption of storage files : political – legal
reasons.
http://ashrafsau.blogspot.in/
32. Adding Nodes ( ½)
A new node can join the network by
discovering the address of one or more
existing nodes.
New nodes must “announce” their
existence.
Existing nodes would like to know to which
keys they should assign the new nodes.
http://ashrafsau.blogspot.in/
33. Adding Nodes (2/2)
Process of joining A Freenet System
Candidate node calculates a random seed
Sends a message to an existing node containing it’s
address and the hash of the seed.
The node that accepts this message generates a
seed XORs it with the hash value of the message and
sends it to a randomly chosen node.
When hops-to-live become 0, all nodes reveal their
seeds.
All seeds are XORed to produce the new node’s key.
Each node add an new entry for the new node in its
routing table under the key.
http://ashrafsau.blogspot.in/
34. Freenet Protocol
Based on messages.
Message form
<Transaction id, Hops-To-Live, Depth counter>
Depth counter incremented at every hop.
Used by the replying node to ensure that
the message will reach the requestor.
http://ashrafsau.blogspot.in/
35. Request Data
The requestor sends a Request.Data message including
the search key.
In case of a successful search, the source of the data
responds to the upstream node with a Send.Data
message.
In case of unsuccessful search or hops-to-live
exhausted, Reply.NotFound message is sent.
If the request reached a dead end or loop detected and
HTL not 0 , a Request.Continue message is sent back to
the upstream node containing the remaining HTL.
the remote node may periodically send back
Reply.Restart messages
http://ashrafsau.blogspot.in/
36. Store Data
The requesting node sends a Request.Insert message
which contains the proposed key.
The store message is propagated from node to node
based on route entries.
In case of a collision a Send.Data message or a
Reply.NotFound message is sent back.
If now more nodes can be accessed but there are HTL, a
Request.Continue message is sent.
If HTL become 0 without having encoutered a collision, a
Reply.Insert message is propagated to the upstream
node.
http://ashrafsau.blogspot.in/
37. Performance Analysis
Network Convergence
Scalability
Fault Tolerance
Small World Model
http://ashrafsau.blogspot.in/
38. Network Convergence (1/2)
1000 nodes.50 items data store each and a
routing table of 150 entries.
Each node has routing entries only for his two
closest neighbors.
Random keys were inserted to random nodes.
Every 100 time steps, 300 random requests for
previously inserted files were performed with
HTL=500.
Request path length = Number of hops taken
before finding the data.
http://ashrafsau.blogspot.in/
40. Scalability (1/2)
20 nodes were used initially.
Inserts and requests were performed
randomly as previously.
Every 5 time steps a new node was
created and inserted to the network.
The announcement message was sent to
a randomly chosen node.
http://ashrafsau.blogspot.in/
42. Fault tolerance (1/2)
Network of 1000 nodes.
Progressively removed randomly chosen nodes
to simulate node failures.
Freenet is extremely robust against node
failures.
The median pathlength remains below 20 even
when up to 30% of the nodes have failed.
http://ashrafsau.blogspot.in/
44. Small World Networks Model
The scalability and fault-tolerance characteristics of
Freenet can be explained in terms of a small-world
network model
The majority of the nodes have a few local connections
to other nodes.
Few nodes have large wide ranging connections.
Nodes are well connected – short paths among them.
Small world networks are fault tolerant.
http://ashrafsau.blogspot.in/
45. Is Freenet a small world?
There must be a scale-free power-law
distribution of links within the network.
http://ashrafsau.blogspot.in/
46. Security issues
Primary goal is protecting the anonymity of
both requestors and inserters of data.
Protect the identity of the node that holds
some specific data.
If a malicious user intends to remove a
data file, he is hindered by the anonymity
of the node that holds the file.
http://ashrafsau.blogspot.in/
47. Free net – Prerouting
Freenet Messages are encrypted by a
succession of public keys which determine the
route that message will follow.
Nodes along the route cannot determine either
the originator of the message or its
contents( since encrypted ).
After the end of the prerouting phase, the
message will be inserted into the Freenet
pretending that the endpoint of the preroute was
the originator of the message.
http://ashrafsau.blogspot.in/
48. Data sources Protection
While a node replies to its upstream node
that he is the source of some file, he can
intentionally hide his address.
http://ashrafsau.blogspot.in/
49. Other security concerns
Modification of requested files.
A node steering all the traffic to itself
pretending it owns all the data files.
DoS Attacks.
Attempting to exhaust the storage space.
“pay” a long computation.
Divide datastore to a “new files” section and to a
“established files” section.
http://ashrafsau.blogspot.in/
50. Gnutella
Many similarities exist between Freenet
and Gnutella
Everyone is visible to everyone else as
long as you are ‘online’
Users are split up into groups
Gnutella employs a broadcast search
for files which grows exponentially
http://ashrafsau.blogspot.in/
51. Napster
Napster has a centralized server, which
does not store any data
It coordinates searches of users
Security risk –
Ifcentralized server is shut down, no way
of distributing files
http://ashrafsau.blogspot.in/
52. Conclusions
Effective means of anonymus information
storage and retrieval.
Highly scalable.
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