As we place more and
more of our lives on internet , it seems that threat to our personal privacy
are also increasing. Even encryption alone cannot ensure freedom and privacy of
users on internet. The routing information is visible to anyone observing the network.
IP addresses that appear in all communication of a user can link all
transactions of a user and can be linked to physical persons, seriously
compromising their privacy.
Anonymous
communication is thus a necessary measure to protect the privacy of users, and
protect computer systems against traffic analysis. Anonymity systems seeks to
build an infrastructure running on top of the existing Internet protocols that
allows people to communicate with each other without necessarily revealing
their personal network identifiers. The basic idea behind any anonymous system
is to provide unlinkability between communicating parties by relaying traffic
through a number of intermediate nodes.
If the messages are delayed and buffered at
these intermediate nodes then they can provide stronger anonymity. Such message
based systems are suitable for high latency anonymous applications such as
anonymous email. Such systems are called Mix based system. Circuit based
randomized routing techniques like Onion Routing and TOR are used for providing
low latency applications like anonymous web browsing or remote login. All these
anonymous systems are used by are used by diverse group of users to protect
their identities on the Internet.
Internet is designed
as a public network. Each time we send an email, visit a Web page, or talk to
friends and family via instant messaging, we send packets of data across the
Internet that contain information regarding where the message is going and who
sent it (e.g., IP addresses, SMTP header information, etc.). As packets are
transmitted via several hops from the source to their destination, anybody
observing a link along that path can roughly identify who is communicating with
whom based on information contained in each packet. Even if the packet data is
encrypted, the source and destination addresses in the packet’s IP header are
still visible to an observer. Thus an observer analyzing this packet header
information can reveal lot of information about communicating parties. This can
raise threat to privacy and freedom of users on internet.
Therefore in
situations where we want strong communication privacy it is needed to hide
routing information of communicating parties from each other and from any
observer conducting traffic analysis. This can be achieved through anonymous
communication. Anonymity systems seeks to build an infrastructure running on
top of the existing Internet protocols that allows people to communicate with
each other without necessarily revealing their personal network identifiers,
such as IP addresses.
Anonymous
communication systems allows communication while keeping user identity secret
by providing unlinkability between between senders and recipients. The basic
idea behind any anonymous system is to relay messages from sender to recipient
through multiple intermediate nodes so that the true origin and destination of
the messages is hidden. Thus it provides unlinkability between communicating
parties. Anonymous systems are therefore used by Private citizens to freely browse
the Web, without advertisers collecting statistics on their personal browsing
habits and selling that personal information to other companies. Also these are
used by are used by diverse groups, such as journalists, human rights workers,
the military, and ordinary citizens, to protect their identities on the
Internet.
The design of
anonymous communication systems are generally classified as
• High Latency
Anonymous Communication
– These are also
known as message-based systems
– They can be used
for non Interactive Traffic applications like Email that can tolerate delays.
– They can provide
stronger anonymity.
– The base of high
latency systems are mixes.
• Low Latency
Anonymous Communication
– These are also
known as connection-based systems.
– These can be used
to provide Interactive Traffic like Web browsing.
– The basic idea
behind low latency systems are randomized routing techniques like Onion routing and
Tor.
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