Security Model

Zero-Knowledge Architecture

All encryption and decryption happens on your machine. The server stores only encrypted blobs in R2 and metadata in D1. Your master password never leaves your device.

Key Derivation

Your master password is transformed into an encryption key using PBKDF2:

• Algorithm: PBKDF2-SHA256
• Iterations: 100,000
• Salt: 32-byte random (generated once during init)
• Output: 32-byte derived key

Encryption

Data is encrypted using AES-256-GCM with a fresh random IV for every encryption operation.

Wire format: [IV 12 bytes][authTag 16 bytes][ciphertext]

Secret Double-Encryption

Secrets receive an additional layer of protection. Each secret has a per-key salt derived from the SHA-256 hash of its key name, combined with the master-derived key. Two secrets with identical values produce different ciphertexts.

File Permissions

All sensitive local files are stored with mode 0600 (owner read/write only). This includes:

• ~/.configsync/secrets.enc
• ~/.configsync/key.salt
• Encrypted module files (SSH keys, credentials)

Secret Providers

For additional security, you can store secrets in external vaults instead of the built-in encrypted file:

• Built-in vault — default, encrypted local file
• OS keychain — macOS Keychain, GNOME Keyring, Windows Credential Manager
• 1Password — via the op CLI
• Bitwarden — via the bw CLI

Transport Security

All communication with the ConfigSync cloud uses TLS 1.3. Since data is encrypted before transmission, even a compromised TLS connection would only expose encrypted blobs.

Environment Protection

Environment protection tiers add a human-verification layer to prevent accidental operations against sensitive environments. See the Environments page for details.