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seedPass/docs/SPEC.md
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# SeedPass Specification
## Key Hierarchy
SeedPass derives a hierarchy of keys from a single BIP-39 parent seed using HKDF:
- **Master Key** `HKDF(seed, "seedpass:v1:master")`
- **KEY_STORAGE** used to encrypt vault data.
- **KEY_INDEX** protects the metadata index.
- **KEY_PW_DERIVE** deterministic password generation.
- **KEY_TOTP_DET** deterministic TOTP secrets.
Each context string keeps derived keys domain separated.
## KDF Parameters
Passwords are protected with **PBKDF2-HMAC-SHA256**. The default work factor is
**50,000 iterations** but may be adjusted via the settings slider. The config
stores a `KdfConfig` structure with the chosen iteration count, algorithm name,
and the current spec version (`CURRENT_KDF_VERSION = 1`). Argon2 is available
with a default `time_cost` of 2 when selected.
## Message Formats
SeedPass synchronizes profiles over Nostr using three event kinds:
- **Manifest (`30070`)** high level snapshot description and current version.
- **Snapshot Chunk (`30071`)** compressed, encrypted portions of the vault.
- **Delta (`30072`)** incremental changes since the last snapshot.
Events encode JSON and include tags for checksums, fingerprints, and timestamps.
## Versioning
Configuration and KDF schemas are versioned so clients can migrate older
profiles. Nostr events carry a version field in the manifest, and the software
follows semantic versioning for releases.
## Memory Protection
SeedPass encrypts sensitive values in memory and attempts to wipe them when no
longer needed. This zeroization is best-effort only; Python's memory management
may retain copies of decrypted data. Critical cryptographic operations may move
to a Rust/WASM module in the future to provide stronger guarantees.