nx_password_vault.nx

nx_password_vault.nx -- sovereign at-rest-encrypted credential store. Per user 2026-05-16: "get that stored in a nishi language equivalent of a password vault so it can be called by authorized users like you". Per cardinals: - feedback-dont-rebuild-commodity-platform-layers: bits-up sovereign, no 1Password / LastPass / Bitwarden / OS keychain DEPENDENCY (we can interop later, but the canonical store is local). - feedback-user-owns-every-bit: vault file lives where the user puts it; primitive does no auto-load, no auto-create, no background daemon, no telemetry. - feedback-launching-content-must-be-one-command-easy: tooling calls vault_get(name) and gets back a credential string. Threat model in scope: - Disk theft: attacker has the encrypted vault file. Must NOT recover plaintext without the master passphrase. - Casual snooping: file is not human-readable. - Offline brute-force: passphrase is the weak link. v1 uses HKDF-SHA256 (FAST kdf) which is INSUFFICIENT against offline brute force on weak passphrases. v2 ships Argon2id integration and migrates existing vaults. Threat model OUT of scope (v1): - Active malware on the host running NishiLang (it can scrape RAM) - Side-channel attacks on the KDF - Vault file rotated without backup before deletion File format (binary, big-endian): magic [8 bytes] = "NXVLT\0\0\1" (version 1) salt [32 bytes] (random; HKDF salt) nonce_base[12 bytes] (random; XOR'd with entry idx) n_entries [4 bytes BE] for each entry i in 0..n_entries: name_len [2 bytes BE] name [name_len bytes] (UTF-8, plaintext) ct_len [4 bytes BE] ct [ct_len bytes] (encrypted value) tag [16 bytes] (Poly1305 tag)