Security

Key Derivation

Obscuro derives your encryption key using Argon2id — a memory-hard algorithm that makes brute-force attacks expensive:

A random salt is generated when you run obscuro init and saved in config.json.

Encryption

All secrets are encrypted with AES-256-GCM (authenticated encryption):

• 32-byte key from Argon2id
• Fresh random 12-byte nonce for every encryption
• Stored as base64(nonce || ciphertext)

GCM gives you both confidentiality and integrity — if anyone tampers with the ciphertext, decryption fails.

Password Verification

During init, Obscuro encrypts the string "obscuro-verify" and saves it in config.json. On every subsequent operation, it decrypts this token first to check that your password is correct before touching any secrets.

Threat Model

You're protected against:

• Reading secrets from disk without the password
• Brute-force attacks (Argon2id is memory-hard)
• Ciphertext tampering (GCM catches it)
• Secrets leaking into git history as plaintext

Not in scope:

• Compromised machines with memory access
• Keyloggers capturing your master password
• Weak master passwords (Argon2id helps, but can't save a trivial password)

Recommendations

• Pick a strong master password — 16+ characters
• Use the OS keychain so you don't have to type it every time
• Rotate secrets with obscuro set KEY using new values
• Keep .obscuro/ committed — it's all encrypted