SecNote — Secure Offline Note-Taking App

A fully offline, encrypted note-taking application for Windows with hardware-backed authentication.

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Features

• AES-256-GCM encryption — every note is encrypted with its own key; the vault is encrypted with a master key
• Windows Hello (TPM) authentication — no password to remember; biometrics or PIN via the TPM
• 24-word BIP-39 recovery key — printed on paper for PIN-change or Hello reset scenarios
• Per-note AAD binding — each note's ciphertext is cryptographically bound to its UUID; blobs cannot be swapped between notes
• Argon2id KDF — 64 MB / 3 iterations for recovery key derivation; GPU brute-force infeasible
• Atomic saves — notes.enc and config.json are written via temp-file + rename; crash-safe
• Config HMAC-SHA256 integrity — tamper detection with constant-time comparison
• Memory locking — master key page locked via VirtualLock; zeroized on drop
• Auto-lock on idle — configurable timeout (default 5 min)
• Vault rollback detection — monotonic vault_version counter protected by HMAC
• Rate-limited recovery — exponential backoff (2 s → 60 s) with 10-attempt hard limit

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Security Properties

Property	Implementation
Encryption	AES-256-GCM with random 96-bit nonces
Key wrapping	AES-256-GCM + AAD role binding
Recovery KDF	Argon2id (64 MB, 3 iter, 1 lane)
Config integrity	HMAC-SHA256, canonical struct encoding, constant-time verify
Memory safety	zeroize + ZeroizeOnDrop on all key material
Auth	Windows Hello (TPM-backed)
Save atomicity	tempfile in same directory + persist() rename
Directory safety	Reparse point / symlink detection on data dir and save dir

Not protected against: same-user malware, admin/SYSTEM memory dumps while unlocked, or nation-state memory scraping. This is a local-data threat model.

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Requirements

• Windows 10 / 11 (Windows Hello required)
• Rust stable toolchain (rustup default stable)

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Build

git clone https://github.com/adikul1023/secnote.git
cd secnote
cargo build --release
# Binary at: target\release\secure-notes.exe

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Running Tests

cargo test

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Security Audit

A full adversarial red-team audit was conducted covering 23 vulnerabilities across cryptographic design, storage, memory safety, and logic. All findings have been remediated.

See VULNERABILITIES.md for the full report including fix details.

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CI

Every push runs:

• cargo audit — known CVE check via RustSec
• cargo deny — license and source policy
• cargo clippy -- -D warnings — lints as hard errors
• cargo test — unit tests (AAD binding, nonce uniqueness, HMAC tamper detection, vault size limits)

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License

MIT — see LICENSE