Understanding Vaultix's security guarantees and limitations.

Vaultix uses a master key encryption model:

1. Master Key (256-bit random): Encrypts all vault data
2. Password Protection: Master key encrypted with Argon2id-derived key
3. Recovery Key (256-bit random): Alternative way to decrypt master key
4. No Plaintext Storage: Master key never stored unencrypted on disk

This architecture provides:

• Dual unlock methods (password OR recovery key)
• Fast password changes (only re-encrypt master key, not all data)
• Recovery option if password forgotten
• Defense in depth (multiple encryption layers)

• Unauthorized file access: Files are encrypted at rest with AES-256-GCM
• Casual snooping: Encrypted data is unreadable without password or recovery key
• Filename leakage: Original filenames are encrypted in metadata
• Data tampering: GCM provides authentication, detecting modifications
• Password loss: Recovery key provides backup access method

• Weak passwords: A guessable password defeats all encryption
• Lost recovery key: If you lose BOTH password AND recovery key, data is permanently lost
• Recovery key exposure: Anyone with recovery key can unlock vault
• Keyloggers/malware: If your system is compromised, passwords can be captured
• Memory attacks: Decrypted data exists in memory during operations
• Physical access: Someone with your password or recovery key and physical access can decrypt
• Legal compulsion: Courts can order you to provide passwords/recovery keys
• Side-channel attacks: Advanced attacks on the cryptographic implementation

Algorithm: Cryptographically Secure Random Number Generator (CSPRNG)

Size: 256 bits (32 bytes)

Purpose:

• Encrypts all vault data (files + metadata)
• Never stored in plaintext
• Encrypted twice: once with password-derived key, once with recovery key

Generation:

masterKey := make([]byte, 32)
crypto/rand.Read(masterKey)

Algorithm: Cryptographically Secure Random Number Generator (CSPRNG)

Size: 256 bits (32 bytes)

Purpose:

• Alternative method to unlock vault
• Can decrypt the master key
• Displayed once during initialization

Format: Hexadecimal string with dashes for readability

5025f74e-c5d7a54a-7b99c87b-78cca1a0-61854d30-fb0d2783-a9df7067-b67ad345

Algorithm: Argon2id (winner of Password Hashing Competition)

Parameters:

• Memory: 64 MB
• Iterations: 1
• Parallelism: 4 threads
• Output: 32 bytes (256 bits)

Why Argon2id?

• Resistant to GPU/ASIC attacks
• Protects against side-channel attacks
• Recommended by OWASP
• Balanced between Argon2i (side-channel resistant) and Argon2d (GPU resistant)

Algorithm: Advanced Encryption Standard with Galois/Counter Mode

Key size: 256 bits
Nonce size: 96 bits (12 bytes)
Authentication tag: 128 bits (16 bytes)

Why AES-256-GCM?

• Industry standard, extensively analyzed
• Provides both confidentiality and authenticity
• Authenticated encryption prevents tampering
• Hardware acceleration available on modern CPUs
• NIST approved

Source: Go's crypto/rand package

Uses OS-provided cryptographically secure random number generators:

• Linux: /dev/urandom
• macOS: SecRandomCopyBytes
• Windows: CryptGenRandom

1. Input: Password entered via terminal (no echo)
2. Derivation: Argon2id generates 256-bit key
3. Usage: Key encrypts/decrypts data
4. Cleanup: Key zeroed in memory after use

Vaultix never stores:

• ✗ Your password
• ✗ Password hashes
• ✗ Password hints
• ✗ Recovery keys

Password correctness is verified by attempting to decrypt the metadata. Incorrect password = decryption failure.

Vaultix enforces:

• Minimum length: 1 character (but please use more!)
• Maximum length: No limit

Recommended:

• At least 16 characters
• Mix of uppercase, lowercase, numbers, symbols
• Use a password manager
• Don't reuse passwords
• Consider a passphrase (e.g., "correct horse battery staple")

Plaintext File
    ↓
Read into memory
    ↓
Generate random nonce
    ↓
AES-256-GCM encryption with derived key
    ↓
Encrypted data + authentication tag
    ↓
Write to .vaultix/objects/
    ↓
Secure delete original file

Encrypted object
    ↓
Read from .vaultix/objects/
    ↓
Extract nonce from ciphertext
    ↓
AES-256-GCM decryption with derived key
    ↓
Verify authentication tag
    ↓
Plaintext data
    ↓
Write to output file

• Original filenames
• File sizes
• Modification timestamps
• Object IDs (encrypted file references)

• Encrypted: Metadata is encrypted with AES-256-GCM
• Authenticated: Tampering is detected
• Single file: All metadata in one encrypted blob

Why encrypt metadata?

Filenames can reveal sensitive information:

• tax_return_2024.pdf → Financial data
• medical_records.txt → Health information
• job_applications.docx → Employment status

When files are deleted (after encryption or with drop/remove):

1. Overwrite: File contents overwritten with random data
2. Delete: File unlinked from filesystem

Limitations:

• SSDs may not physically overwrite due to wear leveling
• Copy-on-write filesystems (Btrfs, ZFS) may keep copies
• Filesystem journaling may preserve data
• Swap/hibernation files may contain plaintext

Recommendation: Use full-disk encryption (LUKS, FileVault, BitLocker) alongside Vaultix.

Attack: Thief gets your laptop with encrypted vault

Protection:

• ✓ Files are encrypted with AES-256
• ✓ Decryption requires password
• ✓ Brute-force is slow (Argon2id)

Outcome: Data is safe if password is strong

Attack: Cloud provider compromised, vault backup leaked

Protection:

• ✓ Vault is fully encrypted
• ✓ Metadata is encrypted
• ✓ Object names don't reveal content

Outcome: Data is safe (same as stolen laptop)

Attack: Keylogger captures password while you use vault

Protection:

• ✗ Password is captured as you type
• ✗ Decrypted files can be read from memory
• ✗ Extracted files can be stolen

Outcome: Vaultix cannot protect against compromised systems

Mitigation: Keep your system clean, use antivirus, practice safe computing

Attack: Someone accesses your computer while you're away

Protection:

• ✗ Files may be extracted
• ✗ Password may be in command history
• ✗ Decrypted files may be on disk

Outcome: Lock your computer when away

Mitigation: Use screen lock, log out, close terminal after vault operations

Attack: Attacker brute-forces your password

Protection:

• ⚠️ Argon2id slows down attacks
• ✗ Weak passwords are still crackable

Outcome: Security depends on password strength

Mitigation: Use strong, unique passwords (16+ characters)

• Use strong, unique passwords
• Store vaults on encrypted drives
• Lock your computer when away
• Keep your OS and software updated
• Use a password manager
• Make encrypted backups
• Test your backups regularly

• Reuse passwords
• Store passwords in plaintext
• Leave decrypted files lying around
• Use vaultix over unencrypted connections
• Trust public computers
• Forget to lock your screen

Vaultix has not undergone formal security auditing. The code is open source for community review, but no independent security firm has assessed it.

Use at your own risk.

If you discover a security vulnerability:

1. DO NOT open a public issue
2. Email security concerns privately
3. Include details and reproduction steps
4. Allow time for fix before disclosure

Vaultix provides strong cryptographic protection for files at rest. However, it's not a silver bullet:

• 🔐 Strong encryption protects data from unauthorized access
• 🔑 Security depends on password strength
• 💻 Cannot protect against compromised systems
• 🎯 Best used alongside other security measures

Think of Vaultix as one layer in your security strategy, not the only layer.