From f196c27faf265cd14d8d7accf58e87b4df3c8a91 Mon Sep 17 00:00:00 2001 From: Doan Luu Duc Tai Date: Fri, 30 Oct 2026 17:04:10 -0500 Subject: Add experimental PQ browser probe and document blocking timing review --- docs/CHAT-DESIGN.txt | 120 ++++++++++++++++++++++++++++++++++++++++++ docs/CHAT-SECURITY-REVIEW.txt | 119 +++++++++++++++++++++++++++++++++++++++++ docs/POLICY.txt | 4 ++ 3 files changed, 243 insertions(+) create mode 100644 docs/CHAT-DESIGN.txt create mode 100644 docs/CHAT-SECURITY-REVIEW.txt (limited to 'docs') diff --git a/docs/CHAT-DESIGN.txt b/docs/CHAT-DESIGN.txt new file mode 100644 index 0000000..7b2a14f --- /dev/null +++ b/docs/CHAT-DESIGN.txt @@ -0,0 +1,120 @@ +Copyright (C) 2026 Doan Luu Duc Tai + +This program is free software: you can redistribute it and/or modify +it under the terms of the GNU Affero General Public License as +published by the Free Software Foundation, either version 3 of the +License, or (at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU Affero General Public License for more details. + +You should have received a copy of the GNU Affero General Public License +along with this program. If not, see . + + +PRIVATE CHAT DESIGN AND LIMITATIONS + + Status: planned application; only the cryptographic compatibility probe + currently exists. This document is a specification, not a completion claim. + Work remains on feature/private-chat. Nothing is deployed to production. + +USER EXPERIENCE + + Entry offers CREATE NEW CHAT and OPEN CHAT FILE. Creation asks for a display + name and password, generates a dedicated identity locally, and downloads one + protected file. The user must reopen that file before sending a first message. + Returning users select the file locally and unlock it with its password. + Usernames are labels; cryptographic identities determine access. + + Show authenticated total, sent, and received message counts. Let the user + select N recent messages, including zero, and page backwards for older ones. + Sending never requires an updated identity file. Scope is text only between + each visitor and Doan, with no public directory, attachments, or group chats. + + Intended host: https://chat.doan.luuduct.ai/ with API under /api/ on the same + origin. It is not configured or deployed yet. The feature branch adds Message + Me links below the name in the home-page box and after Services in navigation. + +CRYPTOGRAPHY AND FILES + + Fixed encryption: RFC 9980 ML-KEM-1024 + X448 with OpenPGP v6 keys. + Test signing profile: ML-DSA-87 + Ed448. Dedicated application identities must + remain separate from Doan's canonical RSA identity. Advise users not to reuse + chat identities elsewhere; exported keys cannot be technically restricted to + this application alone. Future authentication signatures must bind to the + application, origin, conversation, operation, fresh nonce, and expiry. + + The intended chat file contains versioned recovery and identity data, server + identity, and a pinned owner public-key fingerprint. Its exact protected file + format is not finalized. The compatibility probe protects OpenPGP secret-key + material; it does not implement the proposed complete chat-file envelope. + Private keys and passwords must never be uploaded to the server or placed + in a URL, log, analytics event, crash report, or application browser storage. + + Both participants need access to their own stored conversation. The browser + signs and encrypts each message for both participants. The plaintext payload + binds the conversation, sender, unique message ID, and protocol version. + Display names can travel inside encrypted conversation details. + +STATE AND LIMITS + + No intentional persistent browser chat state: no cookies, localStorage, + sessionStorage, IndexedDB, service workers, analytics, or third-party requests. + Keep keys, passwords, session credentials, and loaded history in memory only. + Serve chat content with Cache-Control: no-store. Reload, close, and leave + require the file and password again. Clear references and zero mutable secret + buffers where possible; JavaScript strings and browser/OS copies are not + reliably erasable. Test page restoration and back/forward navigation. + + The downloaded identity file is the intentional persistent client artifact. + Browsers and operating systems may retain memory, swap, crash dumps, download + records, or restored pages. The application cannot promise literally zero + traces. The current browser probe checks only its own limited test behavior. + + The VPS necessarily retains ciphertext, public-key associations, message IDs, + ordering, counts, and authentication state. Connection addresses, timing, and + ciphertext sizes are visible while serving requests. Avoid retaining these + in application/access logs. Storage and encrypted backups require consistent + database snapshots and a tested recovery procedure before actual chat use. + + The private file is a credential. A lost file/password has no username-based + recovery. A copied unlocked identity enables impersonation and historical + decryption. Rotation can protect future use but cannot undo historical + ciphertext or key copies. Static OpenPGP does not automatically provide + forward secrecy. Compromise of a shared owner key can affect every + conversation encrypted to that key. + + The browser trusts served code, including WASM and generated JavaScript. + A compromised server, dependency, extension, browser, or OS may expose keys + or plaintext. A pinned key does not defeat a malicious application update + or solve first-visit trust. A separate origin limits ordinary cross-origin + access, not shared-host compromise or every cross-site attack. + +LIBREJS AND LICENSING + + First-party code is AGPL-3.0-or-later. Third-party licenses and notices remain + accurate. Required legal comments are the exception to the no-comments rule. + Supply machine-readable JS licensing and corresponding Rust/WASM/JS source. + Test actual LibreJS recognition, generated bindings, workers, and WASM before + displaying GNU LibreJS-compliant. The compatibility harness makes no such + claim and is not a public chat application. + + Intended badge: yellow, GNU LibreJS-compliant, linked to + https://www.gnu.org/software/librejs/ . Hover and keyboard focus explain: + + LibreJS compliance concerns software freedom, not a guarantee of privacy + or security. Review the source code, dependencies, and scripts delivered + to your browser. Server-delivered code can change between visits; free + software can still track users or behave maliciously. + +REMAINING RELIABILITY WORK + + Resolve the blocking review in CHAT-SECURITY-REVIEW.txt. Then implement and + test file creation/import, recovery confirmation, signed one-use challenges, + authorization, encrypted sends/replies, replay rejection, N=0 and pagination, + authenticated counters, quotas, rate limits, hostile file and packet limits, + plaintext-only display, session expiry, explicit lock, reload/restoration, + no network leakage, no persistent application storage, and complete backup + restoration. No application is ready merely because its crypto test passes. diff --git a/docs/CHAT-SECURITY-REVIEW.txt b/docs/CHAT-SECURITY-REVIEW.txt new file mode 100644 index 0000000..7de1d36 --- /dev/null +++ b/docs/CHAT-SECURITY-REVIEW.txt @@ -0,0 +1,119 @@ +Copyright (C) 2026 Doan Luu Duc Tai + +This program is free software: you can redistribute it and/or modify +it under the terms of the GNU Affero General Public License as +published by the Free Software Foundation, either version 3 of the +License, or (at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU Affero General Public License for more details. + +You should have received a copy of the GNU Affero General Public License +along with this program. If not, see . + + +CHAT CRYPTOGRAPHY SECURITY REVIEW + + Date: 2026-10-30. Status: blocked for deployment and private-message use. + Branch: feature/private-chat. Production and main remain unchanged. + +FIXED REQUIREMENT + + Encryption must remain RFC 9980 ML-KEM-1024 + X448 using v6 keys. + The compatibility probe pairs it with ML-DSA-87 + Ed448 signatures. + No fallback encryption profile is implemented or approved. + +TEST RESULTS + + Sequoia OpenPGP 2.4.2 with its Rust backend generated password-protected v6 + secret keys, serialized and reimported them, signed UTF-8 content, encrypted + to both participants, and decrypted successfully for both participants. + Wrong passwords, unexpected signers, and modified ciphertext were rejected. + The same probe passed in actual Chromium using Rust compiled to WASM. + + Functional tests are not a cryptographic audit, constant-time analysis, + conformance certification, or demonstration that side channels are absent. + The test uses no user-supplied key files and does not provide chat service. + +RUSTSEC-2026-0387: REACHABLE DEPENDENCY + + Sequoia 2.4.2's crypto-rust backend selects cx448 0.1.1 for both X448 + and Ed448. cx448 depends on crypto-bigint 0.5.5. + + Source paths within these exact published crates: + + sequoia-openpgp/src/crypto/backend/rust/asymmetric.rs + x448_generate_key, x448_derive_public, x448_shared_point + ed448_generate_key, ed448_sign + cx448/src/x448.rs + PublicKey::from(&Secret), Secret::as_diffie_hellman + cx448/src/curve/montgomery.rs + Montgomery scalar multiplication and projective-to-affine conversion + cx448/src/field.rs + elliptic_curve::bigint and constant-modulus Montgomery representation + cx448/src/field/element.rs + field subtraction, multiplication, inversion + cx448/src/field/scalar.rs + scalar arithmetic using crypto-bigint integer operations + + The flagged crate is part of the required curve arithmetic. It cannot be + dismissed as an unused RSA dependency. The advisory covers timing variation + in arithmetic intended to be constant-time and identifies >=0.7.6 as fixed. + cx448 0.1.1 requires the incompatible 0.5 series. Updating Cargo.lock alone + cannot satisfy that requirement with 0.7.6. Source changes or another backend + would require a separate review and tests; no local cryptographic patch has + been invented to bypass this gate. + + This establishes a reachable affected dependency and prevents a claim of + unreachability. It does not prove practical key extraction from this WASM + binary on a particular browser/CPU. No such exploit has been demonstrated. + The hybrid construction's independent component may preserve protection + under some component failures; that is not grounds for ignoring the audit. + + Advisory: https://rustsec.org/advisories/RUSTSEC-2026-0387.html + +RUSTSEC-2023-0071: RSA + + Sequoia's crypto-rust feature also includes rsa 0.9.10. The probe generates + only the specified PQ identities and calls their corresponding primitives; + it does not generate an RSA key or exercise RSA private-key operations. + + That observation applies only to this closed, generated-input probe. It is + not proof that a future importer, certificate verifier, authentication + endpoint, or decryption interface cannot be induced to use another algorithm. + The future application needs an explicit supported-algorithm policy and + hostile-input tests before any narrower exception could be assessed. + + Advisory: https://rustsec.org/advisories/RUSTSEC-2023-0071.html + +BACKEND CHECK + + In the installed Sequoia 2.4.2 source, the Nettle and Botan asymmetric + backends report these required composite algorithms unsupported. The OpenSSL + backend conditionally supports them, depending on the available OpenSSL + version/features. Its browser/WASM build has not been demonstrated here. + Native OpenSSL support alone would not satisfy client-side browser encryption. + + The Rust backend requires allow-experimental-crypto and + allow-variable-time-crypto. These are explicit prototype build opt-ins, + not security approvals or claims that the selected operations are safe. + +OTHER AUDIT GATES + + The new dependency graph also contains multiple crate versions. Its exact + graph is pinned in Cargo.lock. Duplicate bans have not been relaxed, and + no vulnerability advisory has been ignored. License permissions for Sequoia + and its dependencies must remain correctly attributed in generated notices. + + The project check must audit the whole workspace. A root-package-only + cargo-deny invocation misses a workspace member that is not a dependency + of the root CLI. The branch changes that invocation to --workspace. + +NEXT GATE + + Retain the fixed algorithms. Resolve the curve-backend dependency through + a reviewed upstream-compatible fix or demonstrate an acceptable alternative + backend in the browser. Repeat the native and browser tests, review imported + hostile inputs, and pass the full dependency audit before private-message use. diff --git a/docs/POLICY.txt b/docs/POLICY.txt index 592269b..e2cc4a9 100644 --- a/docs/POLICY.txt +++ b/docs/POLICY.txt @@ -73,3 +73,7 @@ PORTABILITY rejects mismatched production images. Development mode may fetch/build native images on an architecture mismatch. Container source and Rust source are public so new targets can be added without restoring an OS. + + Generated third-party legal texts retain upstream whitespace and line endings. + .gitattributes exempts only THIRD-PARTY-LICENSES.html from whitespace errors; + first-party source checks remain strict. Workspace audits include every member. -- cgit v1.2.3