Refraction networking

{{Short description|Internet censorship circumvention technique}}Refraction networking, also known as decoy routing, is a research anti-censorship approach that would allow users to circumvent a censor without using any individual proxy servers.{{Cite web|title=Refraction Networking|url=https://refraction.network/|access-date=2020-12-06|website=refraction.network}} Instead, it implements proxy functionality at the core of partner networks, such as those of Internet service providers, outside the censored country. These networks would discreetly provide censorship circumvention for "any connection that passes through their networks."{{Cite journal|last1=Frolov|first1=Sergey|last2=Douglas|first2=Fred|last3=Scott|first3=Will|last4=McDonald|first4=Allison|last5=VanderSloot|first5=Benjamin|last6=Hynes|first6=Rod|last7=Kruger|first7=Adam|last8=Kallitsis|first8=Michalis|last9=Robinson|first9=David G.|last10=Schultze|first10=Steve|last11=Borisov|first11=Nikita|date=2017|title=An ISP-Scale Deployment of TapDance|url=https://www.usenix.org/conference/foci17/workshop-program/presentation/frolov|language=en}} This prevents censors from selectively blocking proxy servers and makes censorship more expensive, in a strategy similar to collateral freedom.{{Cite news|last=Braga|first=Matthew|date=2017-08-16|title=In fight for free speech, researchers test anti-censorship tool built into the internet's core {{!}} CBC News|language=en-US|work=CBC|url=https://www.cbc.ca/news/technology/tapdance-refraction-networking-decoy-routing-test-usenix-1.4249177|access-date=2020-12-06}}{{Cite web|date=2020-01-29|title=$1M grant to develop secure, high-capacity research network at U-M|url=https://news.engin.umich.edu/2020/01/1m-grant-to-develop-secure-high-capacity-research-network-at-u-m/|access-date=2020-12-06|website=Michigan Engineering|language=en-US}}{{Cite web|date=2017-08-25|title='Clever' TapDance approach to web censorship that works at ISP level|url=https://nakedsecurity.sophos.com/2017/08/25/clever-tapdance-approach-to-web-censorship-that-works-at-isp-level/|access-date=2020-12-06|website=Naked Security|language=en-US}}

The approach was independently invented by teams at the University of Michigan, the University of Illinois, and Raytheon BBN Technologies. There are five existing protocols: Telex,{{Cite web|title=Telex: Anticensorship in the Network Infrastructure {{!}} USENIX|url=https://www.usenix.org/conference/usenix-security-11/telex-anticensorship-network-infrastructure|access-date=2020-12-06|website=www.usenix.org}} TapDance,{{Cite book|last1=Wustrow|first1=Eric|last2=Swanson|first2=Colleen M.|last3=Halderman|first3=J. Alex|date=2014|title=TapDance: End-to-Middle Anticensorship without Flow Blocking|url=https://www.usenix.org/conference/usenixsecurity14/technical-sessions/presentation/wustrow|language=en|pages=159–174|isbn=978-1-931971-15-7}} Cirripede,{{Cite book|last1=Houmansadr|first1=Amir|last2=Nguyen|first2=Giang T.K.|last3=Caesar|first3=Matthew|last4=Borisov|first4=Nikita|title=Proceedings of the 18th ACM conference on Computer and communications security |chapter=Cirripede |date=2011-10-17|chapter-url=https://doi.org/10.1145/2046707.2046730|series=CCS '11|location=Chicago, Illinois, USA|publisher=Association for Computing Machinery|pages=187–200|doi=10.1145/2046707.2046730|isbn=978-1-4503-0948-6|s2cid=11019789}} Curveball,{{Cite web|title=Decoy Routing: Toward Unblockable Internet Communication {{!}} USENIX|url=https://www.usenix.org/conference/foci11/decoy-routing-toward-unblockable-internet-communication|access-date=2020-12-06|website=www.usenix.org}} and Rebound.{{Cite book|last1=Ellard|first1=D.|last2=Jones|first2=C.|last3=Manfredi|first3=V.|last4=Strayer|first4=W. T.|last5=Thapa|first5=B.|last6=Welie|first6=M. Van|last7=Jackson|first7=A.|title=2015 IEEE 40th Conference on Local Computer Networks (LCN) |chapter=Rebound: Decoy routing on asymmetric routes via error messages |chapter-url=https://ieeexplore.ieee.org/document/7366287|year=2015|pages=91–99|doi=10.1109/LCN.2015.7366287|isbn=978-1-4673-6770-7|s2cid=12887876}} These teams are now working together to develop and deploy refraction networking with support from the U.S. Department of State.