Mending Wall: On the Implementation of Censorship in India

TL;DR

This study analyzes India's internet censorship infrastructure, revealing its decentralized implementation, potential for centralized control, and the significant collateral damage that a government-mandated censorship system could cause to global internet traffic.

Contribution

It provides a detailed analysis of India's current censorship practices, infrastructure centralization, and the feasibility and implications of implementing a unified government-controlled filter.

Findings

Indian ISPs implement diverse content filters leading to variable censorship.

A small number of key ASes intercept most censored traffic, enabling centralized filtering.

Federated censorship could cause widespread collateral damage to international traffic.

Abstract

This paper presents a study of the Internet infrastructure in India from the point of view of censorship. First, we show that the current state of affairs---where each ISP implements its own content filters (nominally as per a governmental blacklist)---results in dramatic differences in the censorship experienced by customers. In practice, a well-informed Indian citizen can escape censorship through a judicious choice of service provider. We then consider the question of whether India might potentially follow the Chinese model and institute a single, government-controlled filter. This would not be difficult, as the Indian Internet is quite centralized already. A few "key" ASes (approx 1% of Indian ASes) collectively intercept approx 95% of paths to the censored sites we sample in our study, and also to all publicly-visible DNS servers. 5,000 routers spanning these key ASes would suffice to carry out IP or DNS filtering for the entire country; approx 70% of these routers belong to only two private ISPs. If the government is willing to employ more powerful measures, such as an IP Prefix Hijacking attack, any one of several key ASes can censor traffic for nearly all Indian users. Finally, we demonstrate that such federated censorship by India would cause substantial collateral damage to non-Indian ASes whose traffic passes through Indian cyberspace (which do not legally come under Indian jurisdiction at all).