Thursday, May 5, 2011

The onion and it's Ilk

Historically traffic analysis has been used by government agencies to derive intelligence from messages that may utilize one time pads as a means of perfect forward secrecy . Currently One time pads are still utilized by the various agencies of all industrialized nations in conjunction with numbers stations utilizing shortwave radio as a means to conduct global espionage.  The legacy of the cold war techniques of communications include laws that may have one found with Nitrocellulose paper on their person to be immediately charged with espionage which requires no trial, as the key to a One time pad was usually on these precursors to our sticky notes.

An anonymizer is a protocol or service that creates a secure communications channel by the use cryptographic protocols amongst a pool of proxy servers.

Onion routing is the use of pools of proxies in conjunction with secure sockets layer cryptography to obfuscate the source and destination of a given protocol or message across the internet.
 
Figure 1
The most common implementation of an onion router is the “Tor Project”, this project is an open source initiative that utilizes a network of global proxies to anonymyze web browsing sessions. It is an add on for the Firefox web-browser and operates by creating a proxy interface on the local host computer and then dynamically routing said proxy connection across the internet via a pool of other proxy servers so that the egress of said web-session appears to originate from a remote location.   TOR was originally developed by the Office of Naval Research with the goal of creating a system to be used by the U.S. Navy; it is available publicly at no cost.

Anonymisers are a tool for Military, Global Espionage, Activists operating on the premise of free speech within Dictatorial regimes; and any party that wishes to place a priority on the value of privacy when engaging in communications online. This is a double edges sword as by creating a means to communicate globally in a secure and untraceable manner TOR may also be used by criminals to launch attacks against unwitting victims and thus bypass many forensic tools. Examples include the use of the TOR network by the Russian Business Network to foot print networks within North America that have already implemented “AS” level domain and IP blocking at their firewalls to mitigate such risks. We do need anonymizers as the freedom of speech is the basis of any democratic society; and even industrialized governments have been found to punish any citizens that can be observed dissenting publically.

As an example; In Canada during the recent election students that had been identified by the conservative party were ejected from conservative rallies when they had been observed to be blogging and using twitter at rallies for other parties including the Liberals and NDP. Since the electorate is expected to make an informed decision; these student had committed no offence and broken no law; but were asked to leave on the basis of security, when the true motivation was to prevent them from speaking about their experience at the conservative rally.

In mainland china any dissent is seen as an offence against the state and anyone charged with dissent is placed under house arrest, in some cases permanently. In extreme cases they are sent to re-education institutes or “prisons that offer low cost labor” to various parts of the Chinese economy.

The legal implications within industrialized countries for the use of anonymity tools are to be resolved since there are a number of issues; currently the use of Deep Packet Inspection by large ISP’s within Canada is tantamount to wiretap and is a clear validation of the individual’s right to privacy granted in both the Charter of Rights and Freedoms and the Privacy act; however within Canada Internet service providers use DPI to throttle services that compete with their associated media empires; these include the throttling of peer to peer services and protocols like torrent. These businesses have lobbied to have the judiciaries rule in favor of Deep packet inspection; the reasons are that service providers like “Netflix” may offer a superior product at a competitive price and these providers wish to ensure that a competitor may not use their infrastructure as a delivery mechanism. Other examples include the fact that Youtube a google company is now more popular than most Cable and broadcast companies. These same providers may also use DPI to throttle any Onion routing protocols to an unusable level since most of these protocols do not maintain perfect forward secrecy. Within the united states the use of cryptographic tools are strictly regulated as any cryptographic software is conserved a military grade munition and subject to the same strict controls; ie; the United states government and DoJ views SSL on web-severs with the same level of regulations as laser guided bombs, tank shells and missiles.  The export of any cryptographic software made in the united states is Strictly regulated and may subject any offender to jail time.

The main issue with anonymisers is that by introducing so many encrypted tunnels the latency of the communications channel created has such reduced bandwidth available that it can only be used for asynchronous communications such as web-browsing or the use of instant messaging.  Real-time video, video conferencing and broadcast are currently not feasible as the technical limitations of onion routers reduce the level of available bandwidth to a level that only permits such intermittent use.

References


[i]     Shannon, Claude (Bell Labratories, 1948) Communication Theory of Secrecy Systems, Online [PDF Document] Available from: http://netlab.cs.ucla.edu/wiki/files/shannon1949.pdf (Accessed on May 4th 2011)
[ii]    Sokol, Brett (Miami New Times, February 8th 2001) Espionage is in the Air, Online [World Wide Web] Available from: http://www.miaminewtimes.com/2001-02-08/news/espionage-is-in-the-air/ (Accessed on May 4th 2011)
[iii]  Neal, Harrison (Wikimedia, March 2008) SVG Diagram of the Onion Routing Principal, Online [World Wide Web] Available From: http://en.wikipedia.org/wiki/File:Onion_diagram.svg (Accessed on May 5th 2011)
[iv] N.A. (Tor Project, N.D)  Tor Overview, Online [World Wide Web ] Available from: https://www.torproject.org/about/overview.html.en (Accessed on May 5th 2011)
[v]  Elliot, Louise (CBC, April 5th 2011) Conservative try to explain student ejections from rallies , Online [World Wide Web], Available from: http://www.cbc.ca/news/politics/inside-politics-blog/2011/04/conservatives-try-to-explain-student-ejections-from-rallies.html (Accessed on May 5th 2011)  

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