Security Model¶

OmniVault uses industry-standard cryptographic practices to protect your secrets.

Encryption¶

Algorithm¶

AES-256-GCM (Galois/Counter Mode)

256-bit key size
Authenticated encryption (integrity + confidentiality)
Random 12-byte nonce per secret
NIST-approved algorithm

Key Derivation¶

Argon2id - Winner of the Password Hashing Competition

Parameter	Value	Purpose
Time	3 iterations	CPU cost
Memory	64 MB	Memory cost (GPU resistance)
Threads	4	Parallelism
Key Length	32 bytes	256-bit key
Salt	32 bytes	Random per vault

These parameters follow OWASP recommendations for password hashing.

Why Argon2id?¶

Argon2id is resistant to:

GPU attacks - High memory requirement makes parallel attacks expensive
ASIC attacks - Memory-hard function is difficult to optimize in hardware
Side-channel attacks - Data-independent memory access pattern
Time-memory tradeoff - Hybrid approach resists both

Password Handling¶

Never Stored¶

The master password is:

Used only to derive the encryption key
Never written to disk
Never logged or displayed
Cleared from memory after key derivation

Verification¶

Password correctness is verified by:

Deriving key from entered password
Attempting to decrypt a known "magic" value
Using constant-time comparison to prevent timing attacks

// Constant-time comparison prevents timing attacks
subtle.ConstantTimeCompare(decrypted, expectedMagic)

Minimum Requirements¶

Minimum 8 characters
No maximum length
Any characters allowed

Strong Passwords

Use a passphrase of 4+ random words for better security and memorability.

Storage¶

File Structure¶

macOS / Linux:

~/.omnivault/
├── vault.enc           # Encrypted secrets
├── vault.meta          # Unencrypted metadata
├── omnivaultd.sock     # Unix socket (runtime)
└── omnivaultd.pid      # PID file (runtime)

Windows:

%LOCALAPPDATA%\OmniVault\
├── vault.enc           # Encrypted secrets
├── vault.meta          # Unencrypted metadata
└── omnivaultd.pid      # PID file (runtime)

vault.meta (Unencrypted)¶

Contains non-sensitive metadata:

{
  "version": 1,
  "created_at": "2024-01-15T10:00:00Z",
  "salt": "base64-encoded-32-bytes",
  "argon2_params": {
    "time": 3,
    "memory": 65536,
    "threads": 4,
    "key_len": 32
  },
  "verification": "base64-encrypted-magic"
}

The verification field is an encrypted known value used to verify passwords.

vault.enc (Encrypted)¶

Contains encrypted secrets:

{
  "secrets": {
    "path/to/secret": "base64-nonce+ciphertext+tag"
  }
}

Each secret value is:

Serialized to JSON
Encrypted with AES-256-GCM
Base64 encoded

File Permissions¶

File	Mode	Description
`~/.omnivault/`	700	Owner only
`vault.enc`	600	Owner read/write
`vault.meta`	600	Owner read/write
`omnivaultd.sock`	600	Owner only

Memory Security¶

Key Handling¶

When locked:

// Zero out key before releasing
for i := range key {
    key[i] = 0
}
key = nil

Daemon Isolation¶

Encryption key exists only in daemon memory
CLI never sees the raw key
Key is zeroed on lock or shutdown

Attack Resistance¶

Brute Force¶

Argon2id parameters make brute force expensive:

Each attempt requires 64 MB RAM
Each attempt takes ~1 second on modern hardware
Cannot be parallelized efficiently

Offline Attacks¶

If an attacker obtains vault.enc and vault.meta:

Must still brute force the password
Argon2id parameters are public but still protective
Strong password makes attack infeasible

Replay Attacks¶

Each encryption uses a random nonce:

Same plaintext produces different ciphertext
Replaying old ciphertext is detectable (wrong nonce)

Tampering¶

AES-GCM provides authentication:

Any modification to ciphertext fails decryption
Cannot alter secrets without the key

Best Practices¶

Password Selection¶

Use a strong, unique password
Consider a passphrase (4+ random words)
Use a password manager for the master password

Physical Security¶

Lock your workstation when away
Use full disk encryption
Don't leave vault unlocked unnecessarily

Backup¶

Back up ~/.omnivault/ directory
Store backups securely (encrypted)
Remember: backup is useless without password

Regular Rotation¶

Consider changing your master password periodically:

# Future feature
omnivault change-password

Threat Model¶

Protected Against¶

Unauthorized file access (secrets encrypted)
Memory dumps of CLI process (key in daemon)
Network attacks (Unix socket only)
Tampering (authenticated encryption)
Brute force (Argon2id)

Not Protected Against¶

Keyloggers capturing password
Compromised daemon process
Physical access to unlocked machine
Forgotten password (no recovery)
Sophisticated malware with root access

Comparison¶

Feature	OmniVault	macOS Keychain	1Password
Encryption	AES-256-GCM	AES-256-GCM	AES-256-GCM
KDF	Argon2id	PBKDF2	Argon2id
Open Source	Yes	No	No
Local Only	Yes	Yes	No
Cross-Platform	Yes	macOS only	Yes