new taxonomy, site refactor

Author: 0xalizk

.claude/skills/pir-paper-analyzer/SKILL.md

@@ -2,61 +2,71 @@
 
 ## PIR Engineering Notes
 
-**TLDR**: [Deep reading](https://gist.github.com/0xalizk/50f0d78712c6afe952ab2f9a2cc07434) of PIR papers to extract eng. notes ([eg](research/Group.A.FHE.Based.PIR/thorpir_2024/thorpir_2024_notes.md)) and [visualize](https://0xalizk.github.io/PIR-Eng-Notes/) comparative benchs/asymptotics. The correctness of these notes are [continuously validated](checkups/README.md#checking-correctness-of-cited-claims):
-- Scheme grouping [based on this taxonomy](https://hackmd.io/@keewoolee/SJyGoXCzZe#Taxonomy)
+**TLDR**: [Deep reading](https://gist.github.com/0xalizk/50f0d78712c6afe952ab2f9a2cc07434) of PIR papers to extract eng. notes ([eg](research/Group.2b.Interactive.Hint/thorpir_2024/thorpir_2024_notes.md)) and [visualize](https://0xalizk.github.io/PIR-Eng-Notes/) comparative benchs/asymptotics. The correctness of these notes are [continuously validated](checkups/README.md#checking-correctness-of-cited-claims):
+- Scheme grouping [based on this taxonomy](https://notes.ethereum.org/U9xM4VOPR9isPK7lOZJUQg?view#41-Taxonomy) (client state architecture)
 - Multi-server schemes are excluded
-- Engineering notes ([eg](/research/Group.A.FHE.Based.PIR/thorpir_2024/thorpir_2024_notes.md)) for 28 Private Information Retrieval (PIR) research papers with  [validated](https://github.com/0xalizk/PIR-Eng-Notes/tree/main/.claude/skills/footnotes-checkup) [[2]](https://github.com/0xalizk/PIR-Eng-Notes/tree/main/checkups#checking-correctness-of-cited-claims) footnotes [eg](https://github.com/0xalizk/PIR-Eng-Notes/blob/main/research/Group.A.FHE.Based.PIR/thorpir_2024/thorpir_2024_notes.md#user-content-fn-1-3308a358ac26db24fd1f223243da4392)
+- Engineering notes ([eg](research/Group.2b.Interactive.Hint/thorpir_2024/thorpir_2024_notes.md)) for 30 Private Information Retrieval (PIR) scheme entries with [validated](https://github.com/0xalizk/PIR-Eng-Notes/tree/main/.claude/skills/footnotes-checkup) [[2]](https://github.com/0xalizk/PIR-Eng-Notes/tree/main/checkups#checking-correctness-of-cited-claims) footnotes
 - Per-scheme notes are produced by reading the source PDF (incl. tables/figures which Claude can do) using a [standardized methodology](.claude/skills/pir-paper-analyzer/SKILL.md).
+- Classification rationale for each scheme is documented in [research/README.md](research/README.md)
 
 | [![Communication](docs/img/communication.png)](https://0xalizk.github.io/PIR-Eng-Notes/reported/#communication) | [![Server Performance](docs/img/server-perf.png)](https://0xalizk.github.io/PIR-Eng-Notes/reported/#server-perf) | [![Offline & Storage](docs/img/offline-storage.png)](https://0xalizk.github.io/PIR-Eng-Notes/reported/#offline-storage) |
 |:---:|:---:|:---:|
 
-### Group A — FHE-Based PIR
+### Group 1a — Stateless Client, Stateful Server
+
+Server caches per-client cryptographic material (evaluation keys). Queries linkable across sessions.
 
 | Paper               | Key Contribution |
 |-------------------------------|-----------------|
-| 2025 [OnionPIRv2](research/Group.A.FHE.Based.PIR/onionpirv2_2025/onionpirv2_2025_notes.md) | Multi-base decomposition + NTT-domain DB engineering |
-| 2024 [ThorPIR](research/Group.A.FHE.Based.PIR/thorpir_2024/thorpir_2024_notes.md) | Client-dependent FHE preprocessing (functionally Group D) |
-| 2022 [FrodoPIR](research/Group.A.FHE.Based.PIR/frodopir_2022/frodopir_2022_notes.md) | Plain LWE with client-independent global hint (functionally Group C) |
-| 2022 [Spiral](research/Group.A.FHE.Based.PIR/spiral_2022/spiral_2022_notes.md) | Ciphertext translation (Regev-to-GSW), 4 Pareto-optimal variants |
-| 2022 [CwPIR](research/Group.A.FHE.Based.PIR/cwpir_2022/cwpir_2022_notes.md) | Constant-weight equality operators, native keyword PIR |
-| 2021 [FastPIR/Addra](research/Group.A.FHE.Based.PIR/addra_2021/addra_2021_notes.md) | System: metadata-private voice via one-hot BFV selection |
-| 2021 [OnionPIR](research/Group.A.FHE.Based.PIR/onionpir_2021/onionpir_2021_notes.md) | External products for noise control, first <1s at scale |
-| 2019 [MulPIR](research/Group.A.FHE.Based.PIR/mulpir_2019/mulpir_2019_notes.md) | GSW-based compressible FHE for high communication rate |
-| 2018 [SealPIR](research/Group.A.FHE.Based.PIR/sealpir_2018/sealpir_2018_notes.md) | Query compression via BFV oblivious expansion (paradigm shift) |
-| 2016 [XPIR-2016](research/Group.A.FHE.Based.PIR/xpir_2016/xpir_2016_notes.md) | Ring-LWE system with auto-optimization of parameters |
-| 2014 [XPIR-2014](research/Group.A.FHE.Based.PIR/xpir_2014/xpir_2014_notes.md) | First practical NTRU-based single-server cPIR |
-
-### Group B — Stateless Single Server PIR
+| 2026 [NPIR](research/Group.1a.Stateless.Client.Stateful.Server/npir_2026/NPIR_2026_notes.md) | NTRU packing for high communication rate |
+| 2025 [VIA-BC](research/Group.1b.Stateless.Client.Stateless.Server/via_2025/VIA_2025_notes.md) | VIA-C/VIA-B variants: LWE-to-RLWE query compression + batch repacking; 14.8 MB per-client eval keys |
+| 2025 [OnionPIRv2](research/Group.1a.Stateless.Client.Stateful.Server/onionpirv2_2025/onionpirv2_2025_notes.md) | Multi-base decomposition + NTT-domain DB engineering |
+| 2025 [Pirouette](research/Group.1a.Stateless.Client.Stateful.Server/pirouette_2025/Pirouette_2025_notes.md) | 36-byte queries via blind rotation |
+| 2024 [WhisPIR](research/Group.1a.Stateless.Client.Stateful.Server/whispir_2024/WhisPIR_2024_notes.md) | BGV-based, non-compact BGV optimization |
+| 2024 [Respire](research/Group.1a.Stateless.Client.Stateful.Server/respire_2024/Respire_2024_notes.md) | Small-record optimization, 5-ring architecture |
+| 2022 [Spiral](research/Group.1a.Stateless.Client.Stateful.Server/spiral_2022/spiral_2022_notes.md) | Ciphertext translation (Regev-to-GSW), 4 Pareto-optimal variants |
+| 2022 [CwPIR](research/Group.1a.Stateless.Client.Stateful.Server/cwpir_2022/cwpir_2022_notes.md) | Constant-weight equality operators, native keyword PIR |
+| 2021 [FastPIR/Addra](research/Group.1a.Stateless.Client.Stateful.Server/addra_2021/addra_2021_notes.md) | System: metadata-private voice via one-hot BFV selection |
+| 2021 [OnionPIR](research/Group.1a.Stateless.Client.Stateful.Server/onionpir_2021/onionpir_2021_notes.md) | External products for noise control, first <1s at scale |
+| 2019 [MulPIR](research/Group.1a.Stateless.Client.Stateful.Server/mulpir_2019/mulpir_2019_notes.md) | GSW-based compressible FHE for high communication rate |
+| 2018 [SealPIR](research/Group.1a.Stateless.Client.Stateful.Server/sealpir_2018/sealpir_2018_notes.md) | Query compression via BFV oblivious expansion (paradigm shift) |
+| 2016 [XPIR-2016](research/Group.1a.Stateless.Client.Stateful.Server/xpir_2016/xpir_2016_notes.md) | Ring-LWE system with auto-optimization of parameters |
+| 2014 [XPIR-2014](research/Group.1a.Stateless.Client.Stateful.Server/xpir_2014/xpir_2014_notes.md) | First practical NTRU-based single-server cPIR |
+
+### Group 1b — Stateless Client, Stateless Server
+
+No per-client state anywhere. Server preprocesses DB into a shared structure.
 
 | Paper &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | Key Contribution |
 |-------------------------------|-----------------|
-| 2026 [NPIR](research/Group.B.Stateless.Single.Server.PIR/npir_2026/NPIR_2026_notes.md) | NTRU packing for high communication rate |
-| 2025 [VIA](research/Group.B.Stateless.Single.Server.PIR/via_2025/VIA_2025_notes.md) | DMux-CMux architecture, 3 variants (VIA/VIA-C/VIA-B) |
-| 2025 [InsPIRe](research/Group.B.Stateless.Single.Server.PIR/inspire_2025/InsPIRe_2025_notes.md) | InspiRING ring packing, polynomial evaluation |
-| 2025 [Pirouette](research/Group.B.Stateless.Single.Server.PIR/pirouette_2025/Pirouette_2025_notes.md) | 36-byte queries via blind rotation |
-| 2024 [WhisPIR](research/Group.B.Stateless.Single.Server.PIR/whispir_2024/WhisPIR_2024_notes.md) | BGV-based stateless PIR, non-compact BGV optimization |
-| 2024 [Respire](research/Group.B.Stateless.Single.Server.PIR/respire_2024/Respire_2024_notes.md) | Small-record optimization, 5-ring architecture |
-| 2024 [YPIR](research/Group.B.Stateless.Single.Server.PIR/ypir_2024/YPIR_2024_notes.md) | Memory-bandwidth-limited throughput, CDKS packing |
-| 2023 [HintlessPIR](research/Group.B.Stateless.Single.Server.PIR/hintlesspir_2023/HintlessPIR_2023_notes.md) | Composable RLWE preprocessing, LinPIR primitive |
+| 2025 [VIA](research/Group.1b.Stateless.Client.Stateless.Server/via_2025/VIA_2025_notes.md) | DMux-CMux architecture, fully hintless (base variant) |
+| 2025 [InsPIRe](research/Group.1b.Stateless.Client.Stateless.Server/inspire_2025/InsPIRe_2025_notes.md) | InspiRING ring packing, polynomial evaluation |
+| 2024 [YPIR](research/Group.1b.Stateless.Client.Stateless.Server/ypir_2024/YPIR_2024_notes.md) | Memory-bandwidth-limited throughput, CDKS packing |
+| 2023 [HintlessPIR](research/Group.1b.Stateless.Client.Stateless.Server/hintlesspir_2023/HintlessPIR_2023_notes.md) | Composable RLWE preprocessing, LinPIR primitive |
+
+### Group 2a — Download-Hint
 
-### Group C — Client-Independent Preprocessing
+Client downloads server-computed global hint. Hint generation is server→client only (one-directional).
 
 | Paper &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | Key Contribution |
 |-------------------------------|-----------------|
-| 2026 [IncrementalPIR](research/Group.C.Client.Independent.Preprocessing/incrementalpir_2026/IncrementalPIR_2026_notes.md) | Entry-level incremental preprocessing for SimplePIR |
-| 2024 [VeriSimplePIR](research/Group.C.Client.Independent.Preprocessing/verisimplepir_2024/VeriSimplePIR_2024_notes.md) | Verifiability via SIS commitments + VLHE |
-| 2022 [DoublePIR](research/Group.C.Client.Independent.Preprocessing/simplepir_doublepir_2022/SimplePIR_DoublePIR_2022_notes.md) | Compressed hints via LWE-on-LWE composition |
-| 2022 [SimplePIR](research/Group.C.Client.Independent.Preprocessing/simplepir_doublepir_2022/SimplePIR_DoublePIR_2022_notes.md) | 10 GB/s throughput via plain LWE matrix-vector multiply |
+| 2026 [IncrementalPIR](research/Group.2a.Download.Hint/incrementalpir_2026/IncrementalPIR_2026_notes.md) | Entry-level incremental preprocessing for SimplePIR |
+| 2024 [VeriSimplePIR](research/Group.2a.Download.Hint/verisimplepir_2024/VeriSimplePIR_2024_notes.md) | Verifiability via SIS commitments + VLHE |
+| 2022 [FrodoPIR](research/Group.2a.Download.Hint/frodopir_2022/frodopir_2022_notes.md) | Plain LWE with client-independent global hint |
+| 2022 [DoublePIR](research/Group.2a.Download.Hint/simplepir_doublepir_2022/SimplePIR_DoublePIR_2022_notes.md) | Compressed hints via LWE-on-LWE composition |
+| 2022 [SimplePIR](research/Group.2a.Download.Hint/simplepir_doublepir_2022/SimplePIR_DoublePIR_2022_notes.md) | 10 GB/s throughput via plain LWE matrix-vector multiply |
+
+### Group 2b — Interactive-Hint
 
-### Group D — Client-Dependent Preprocessing
+Hint generation requires client↔server communication. Only category achieving sublinear online server time.
 
 | Paper &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; | Key Contribution |
 |-------------------------------|-----------------|
-| 2024 [WangRen](research/Group.D.Client.Dependent.Preprocessing/wangren_2024/WangRen_2024_notes.md) | Tight ST = O(nw) tradeoff (theory) |
-| 2024 [Plinko](research/Group.D.Client.Dependent.Preprocessing/plinko_2024/Plinko_2024_notes.md) | Invertible PRFs, Õ(1) updates (theory) |
-| 2024 [RMS24](research/Group.D.Client.Dependent.Preprocessing/rms24_2024/RMS24_2024_notes.md) | Dummy subsets, standard correctness |
-| 2023 [Piano](research/Group.D.Client.Dependent.Preprocessing/piano_2023/Piano_2023_notes.md) | First practical sublinear-server, PRF-only |
+| 2024 [ThorPIR](research/Group.2b.Interactive.Hint/thorpir_2024/thorpir_2024_notes.md) | Client-dependent FHE preprocessing |
+| 2024 [WangRen](research/Group.2b.Interactive.Hint/wangren_2024/WangRen_2024_notes.md) | Tight ST = O(nw) tradeoff (theory) |
+| 2024 [Plinko](research/Group.2b.Interactive.Hint/plinko_2024/Plinko_2024_notes.md) | Invertible PRFs, Õ(1) updates (theory) |
+| 2024 [RMS24](research/Group.2b.Interactive.Hint/rms24_2024/RMS24_2024_notes.md) | Dummy subsets, standard correctness |
+| 2023 [Piano](research/Group.2b.Interactive.Hint/piano_2023/Piano_2023_notes.md) | First practical sublinear-server, PRF-only |
 
 ### Group X — Extensions
 
@@ -65,13 +75,4 @@
 | 2025 [DistributionalPIR](research/Group.X.Extensions/distributionalpir_2025/DistributionalPIR_2025_notes.md) | Distribution-dependent PIR model + compiler framework |
 | 2019 [KeywordPIR](research/Group.X.Extensions/keywordpir_2019/KeywordPIR_2019_notes.md)&#8201;[^1] | Comparison of SealPIR, MulPIR, Gentry-Ramzan for keyword PIR |
 
-[^1]: The "MulPIR" referenced in KeywordPIR is the Ali et al. [[1]](https://eprint.iacr.org/2019/1483) implementation of Gentry & Halevi's "Compressible FHE with Applications to PIR" [[2]](https://eprint.iacr.org/2019/733), which is already covered under [mulpir_2019](research/Group.A.FHE.Based.PIR/mulpir_2019/mulpir_2019_notes.md#mulpir--engineering-notes). Open-source implementations: [[3](https://github.com/apple/swift-homomorphic-encryption)] [[4](https://github.com/tlepoint/fhe.rs)].
-
-### Note: schemes below span multiple groups
-
-| &nbsp; &nbsp; &nbsp; &nbsp; $\color{darkorange}{\textsf{Scheme}}$ &nbsp; &nbsp; &nbsp; &nbsp; | $\color{darkorange}{\textsf{Why}}$ |
-|:----------------------------------------------------------------------:|-----|
-| 2025&nbsp;[VIA](research/Group.B.Stateless.Single.Server.PIR/via_2025/VIA_2025_notes.md) | Base VIA is Group B (hintless); VIA-C straddles B/C — its offline evaluation-key upload is client-independent preprocessing |
-| 2024&nbsp;[ThorPIR](research/Group.A.FHE.Based.PIR/thorpir_2024/thorpir_2024_notes.md) | Group A + D hybrid — FHE-based construction, but client sends encrypted PRG seeds and server performs per-client homomorphic preprocessing |
-| 2022&nbsp;[FrodoPIR](research/Group.A.FHE.Based.PIR/frodopir_2022/frodopir_2022_notes.md) | Filed A (LWE-based) but functionally Group C — server computes a single client-independent global hint matrix; no per-client preprocessing |
-| 2022&nbsp;[CwPIR](research/Group.A.FHE.Based.PIR/cwpir_2022/cwpir_2022_notes.md) | Filed A (FHE-based) but its core innovation — constant-weight equality operators — enables native single-round keyword PIR (a Group X extension model) |
+[^1]: The "MulPIR" referenced in KeywordPIR is the Ali et al. [[1]](https://eprint.iacr.org/2019/1483) implementation of Gentry & Halevi's "Compressible FHE with Applications to PIR" [[2]](https://eprint.iacr.org/2019/733), which is already covered under [mulpir_2019](research/Group.1a.Stateless.Client.Stateful.Server/mulpir_2019/mulpir_2019_notes.md#mulpir--engineering-notes). Open-source implementations: [[3](https://github.com/apple/swift-homomorphic-encryption)] [[4](https://github.com/tlepoint/fhe.rs)].

README.md

@@ -1,4 +1,4 @@
 ## PIR Implementations
 
-- [S3PIR](https://github.com/renling/S3PIR) (C++) — RMS24 single-server PIR. See also [notes](../../research/Group.D.Client.Dependent.Preprocessing/rms24_2024/RMS24_2024_notes.md).
-- [rms24-plinko-spec](https://github.com/keewoolee/rms24-plinko-spec) (Python) — Reference spec for RMS24 + Plinko. See also [notes](../../research/Group.D.Client.Dependent.Preprocessing/plinko_2024/Plinko_2024_notes.md).
+- [S3PIR](https://github.com/renling/S3PIR) (C++) — RMS24 single-server PIR. See also [notes](../../research/Group.2b.Interactive.Hint/rms24_2024/RMS24_2024_notes.md).
+- [rms24-plinko-spec](https://github.com/keewoolee/rms24-plinko-spec) (Python) — Reference spec for RMS24 + Plinko. See also [notes](../../research/Group.2b.Interactive.Hint/plinko_2024/Plinko_2024_notes.md).