One-way indexing separates a published file into encrypted content blocks (indexed by hash1(block)), a content manifest (indexed by hash2(keyword)), and a key manifest (indexed by hash3(keyword)), so a storer holding all content chunks cannot recover the plaintext or keywords without inverting a cryptographic one-way function. Using distinct hash functions for each manifest type also minimizes the probability that a single node stores both manifests, preventing correlation.

Content-oblivious replication delegates ongoing availability maintenance to 'manifest guarantors' — nodes holding content manifests — who periodically sample chunk replication factors and restore missing replicas without knowing the plaintext they protect, freeing the original publisher from any post-publication obligation. Two honest manifest holders (one content, one key) are sufficient to maintain replication with overwhelming probability even under adversarial conditions and high churn.

§3.3 defense

Simulation over erasure code parameters uniformly sampled from m∈[1,5] and n∈[5,500] shows that a 50-of-500 code is the best trade-off between overhead and robustness: it requires nearly 10× storage overhead to support 2^60 variable-size chunks and allows the network to tolerate more than 70% node failure before data is lost. Replication combined with erasure coding yields better durability than either strategy alone.

§4, Figure 2 evaluation

A hybrid garbage-collection scheme combining time-based expiry (last-access timestamp cutoff), popularity-based retention, and editor-signed manifest exemptions forces adversaries conducting pollution or exhaustion attacks to continuously re-access or re-upload junk to prevent its deletion. A single honest editor's signature is sufficient to exempt important but infrequently accessed content from deletion indefinitely, while malicious editors cannot explicitly remove content from the system.

§3.3 defense

In a 250-node PlanetLab deployment with 10–15% silent node failures and high churn, the median user retrieved a 20MB file in 65–85 seconds end-to-end (search + manifest download + chunk fetch + reconstruction + decryption). 15.12% of DHT lookups and 11.24% of maintenance operations failed; 20% of nodes accounted for 80% of failures, yet nodes with working connections completed lookups and maintained sufficient guarantors for manifest replication.

§4.1, Figure 3 evaluation

IRBlock discovered that 1.7M of 3.3M blocked apex domains (52%) were attributed to blanket suffix-level blocking rules rather than individual domain listings. Examples include regex patterns targeting all Israeli domains (.il TLD), adult content (.porn), and country-coded suffixes (.com.mx, .my.id). Of 87K Tranco-ranked apex domains analyzed, 37% fell into adult content, with entertainment and gambling following. Approximately 1.27M apex domains were jointly censored by both DNS and HTTP filters, while the two filters maintained operationally independent blocklists for a significant fraction of domains.

2025-tai-irblock §5.3 dns-poisoningip-blockingkeyword-filtering

For Tier 2 apps (IP geo-blocking only), using a VPN with a foreign endpoint was sufficient to restore access. For Tier 1 apps (SIM + IP geo-blocking), the authors confirmed that (1) removing the Indian SIM card and accessing via WiFi, or (2) intercepting HTTP traffic with a MITM proxy to suppress or rewrite the carrier_region=IN parameter, fully bypassed server-side censorship. The authors note that Indian users primarily rely on mobile Internet, making SIM removal impractical as a user-facing solution.

2024-gosain-out §4.3, §5 ip-blockingkeyword-filtering

After India imposed a permanent ban in January 2021, seven of the eight previously SIM-only-blocked apps escalated to dual-factor filtering: they continued extracting carrier_region=IN from the SIM card while simultaneously adding IP geo-blocking. Accessing these apps now requires both a VPN (for source IP masking) and SIM removal or carrier_region parameter suppression; MICO Chat remained the sole app using only SIM-based blocking.

2024-gosain-out §4.3 (Permanent ban subsection), Table 2 ip-blockingkeyword-filtering

Seven of the 220 banned apps (Tier 1, including TikTok, Likee, Kwai, UC Browser, FaceU, Hago, and V-Fly) used the Android TelephonyManager.getSimCountryISO() API to read the primary SIM's country code and embed a carrier_region=IN parameter in HTTP requests, enabling server-side identification and blocking of Indian users regardless of source IP or VPN state. A dual-SIM phone with an Indian SIM in the secondary slot only (primary empty or non-Indian) bypassed the check.

2024-gosain-out §4.3 ip-blockingkeyword-filtering

GFWeb tested 1.02 billion domains against the GFW over 20 months and discovered 943,000 pay-level domains blocked by HTTP filters and 55,000 by HTTPS filters — the largest GFW blocklist dataset ever published. The HTTP-to-HTTPS ratio (17:1) confirms that the GFW's HTTPS keyword-based and SNI-based blocking covers far fewer domains than its HTTP host-header blocking, likely because HTTPS blocks carry higher collateral-damage risk.

2024-hoang-gfweb Abstract, §5.1 dpidns-poisoningip-blockingkeyword-filteringsni-blocking

The largest measurement study of Turkmenistan censorship to date tested 15.5 million domains and found more than 122,000 domains censored using separate blocklists for DNS, HTTP, and HTTPS. Reverse-engineering the blocking rules revealed approximately 6,000 over-blocking rules that cause incidental filtering of more than 5.4 million additional domains — a 44x collateral damage ratio relative to intentionally blocked domains.

2023-nourin-measuring §Results dns-poisoningdpikeyword-filteringip-blocking