Robustness principle: Difference between revisions

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In 2001, [[Marshall Rose]] characterized several deployment problems when applying Postel's principle in the design of a new application protocol.<ref>{{cite IETF |title=On the Design of Application Protocols |rfc=3117 |last=Rose |first=M. |authorlink=Marshall Rose |year=2001 |month=November |publisher=[[Internet Engineering Task Force|IETF]] |accessdate=June 9, 2014}}</ref> For example, a defective implementation that sends non-conforming messages might be used only with implementations that tolerate those deviations from the specification until, possibly several years later, it is connected with a less tolerant application that rejects its messages. In such a situation, identifying the problem is often difficult, and deploying a solution can be costly. Rose therefore recommended "explicit consistency checks in a protocol&nbsp;... even if they impose implementation overhead".

InFrom 2015 to 2018, in a 2017series of [[Internet-Draft]]s, Martin Thomson argues that Postel's robustness principle actually leads to a ''lack'' of robustness, including security.<ref>{{cite IETF |title=The Harmful Consequences of Postel'sthe Robustness MaximPrinciple |last=Thomson |first=Martin |year=20172018 |month=October |url=https://tools.ietf.org/html/draft-thomsoniab-postelprotocol-wasmaintenance-wrong-0201 |publisher=[[Internet Engineering Task Force|IETF]] |accessdate=JanuaryOctober 1525, 2018}}</ref>

In 2018, a paper on [[privacy-enhancing technologies]] by Florentin Rochet and Olivier Pereira showed how to exploit Postel's robustness principle inside the [[Tor (anonymity network)|Tor]] [[Onion routing|routing protocol]] to compromise the anonymity of onion services and Tor clients.<ref>{{cite journal | url = https://petsymposium.org/2018/files/papers/issue2/popets-2018-0011.pdf | title = Dropping on the Edge: Flexibility and Traffic Confirmation in Onion Routing Protocols | authors = Florentin Rochet and Olivier Pereira | journal = Proceedings of the Privacy Enhancing Technologies Symposium | issn = 2299-0984 | publisher = De Gruyter Open | year = 2018 | issue = 2 | pages = 27–46 }}</ref>