The paper identifies a structural conflict between Internet research's scalability imperative — where a project processing millions of devices is considered superior — and human-subjects ethics frameworks designed to minimize the number of people exposed to risk. Under U.S. law, Encore is compliant because it exploits known, intentional web functionality (the same-origin policy's cross-origin request mechanism) and provides an opt-out mechanism, but the authors note this compliance does not transfer to all jurisdictions where measurements occur.

The Encore system collected censorship measurements from 88,260 distinct IP addresses across 170 countries over seven months via installations by at least 17 volunteer website operators. China, India, the United Kingdom, and Brazil each contributed at least 1,000 measurements; Egypt, South Korea, Iran, Pakistan, Turkey, and Saudi Arabia each contributed more than 100.

Introduction evaluation

ACM SIGCOMM 2015's program committee accepted the Encore paper with an unprecedented 'signing statement' after heated ethical debate. The committee's core objections were: (1) users accessing censored URLs might face repercussions in regimes without due process; (2) most users under censorship would be unlikely to consent to the measurements; and (3) unlike ad-tracker third-party requests, Encore requests do not reflect any user intent.

Ethical Oversight by Program Committees policy

To mitigate harm, Encore restricted its URL list to Twitter, Facebook, and YouTube on the grounds that widgets from these domains appear in ordinary web browsing, making Encore-induced cross-origin requests statistically indistinguishable from normal traffic. The authors argued that this renders the risk comparable to baseline browsing, though the SIGCOMM committee disputed whether contextual equivalence with ad-tracking constitutes adequate ethical justification.

Mitigating Harm policy

Encore's architecture turns ordinary web visitors into measurement vantage points, which the researchers argue prevents censors from detecting and disabling dedicated measurement probes. However, this benefit comes with the trade-off that the individuals whose browsers are co-opted face potential legal or physical risk that differs by country and by the specific censored content accessed.

Background / Analysis policy

'Resource Inaccessible' was the most frequently reported issue (61% of 119 submitted reports) during a month of naturalistic Tor Browser browsing, followed by CAPTCHAs (18%), Broken Content (17%), Other Issues (13%), and Timeouts (5%). These categories document the operational failure modes that degrade everyday Tor Browser usability beyond protocol-level censorship.

2026-micallef-reportor-facilitating-user §6.1, Figure 3 ip-blockingmeasurement-platform

The privacy properties of Tor Browser structurally preclude automated telemetry collection, creating a persistent blind spot for diagnosing user experience failures at scale. ReporTor demonstrates that anonymous voluntary in-situ reporting — transmitted over the Tor network and stored in a password-protected onion-service database — can substitute for telemetry: 119 reports over one month from five expert users sufficed to reproduce approximately half of reported issues exactly and identify root causes for most of the remainder.

2026-micallef-reportor-facilitating-user §1, §7.1 measurement-platform

A compiled blocklist dataset documents 43,083 apex domains blocked via DNS filtering across 6 Indian ISPs, representing one of the largest systematic inventories of Indian DNS censorship scope published to date.

2026-qurbat-list-domains-blocked compiled_blocklist.csv (main dataset) dns-poisoningmeasurement-platform

The dataset incorporates Tranco popularity rankings for blocked domains (derived from the 'Poisoned Wells' research), enabling measurement of how DNS blocking in India intersects with high-traffic websites rather than being confined to obscure domains.

2026-qurbat-list-domains-blocked Abstract (Tranco ranking annotation) dns-poisoningmeasurement-platform

The blocklist spans 6 distinct Indian ISPs, enabling cross-ISP consistency analysis; the multi-ISP scope reflects that DNS-based blocking in India is implemented heterogeneously at the ISP level rather than via a single national chokepoint.

2026-qurbat-list-domains-blocked Abstract / dataset metadata dns-poisoningmeasurement-platform

The largest single source of censored domains in the GNL is MESA lab's SNI monitoring dataset (E21-SNI-Top200w.txt) containing 57,362 censored domains, and E21-SNI-Top120W-20221020.txt with 36,467 domains—totaling over 93K domains from network tap data alone for a single country (E21 = Ethiopia per InterSecLab attribution). A separate Xinjiang dataset (XJ-CUCC-SNI-Top200w.txt) contains 13,604 domains. These datasets "do not seem to come from popular domain lists, and instead appear to be gathered from network taps," confirming that Geedge builds censorship target lists directly from passive traffic observation.

2026-sheffey-geedge §4.2, Table 3 dpisni-blockingmeasurement-platform