Security

Master Password & Key Derivation

When you initialize ConfigSync, you set a master password. This password is never stored or transmitted. Instead, a cryptographic key is derived from it using:

• Algorithm: PBKDF2 with SHA-256
• Iterations: 100,000 (resistant to brute-force attacks)
• Salt: Cryptographically random 32 bytes, unique per installation
• Output: 32-byte key used for AES-256-GCM encryption

The derived key stays in memory only while the CLI is running. It is never written to disk in plaintext.

Data Encryption

All sensitive data is encrypted using AES-256-GCM, which provides:

• Cipher: AES-256 in GCM mode (256-bit key)
• Authentication: Built-in GCM authentication tag (prevents tampering)
• IV: Unique random 12-byte initialization vector per encryption operation
• Wire format: [IV (12 bytes)][Auth Tag (16 bytes)][Ciphertext]

AES-256-GCM is an authenticated encryption standard provided by Node.js's built-in node:crypto module. It guarantees that data encrypted with it cannot be read or altered without the key.

Individual Secret Protection

Secrets stored via configsync secret set receive an additional layer of protection:

• Each secret is salted with a SHA-256 hash derived from its key name
• The salted value is encrypted with AES-256-GCM
• The entire secrets vault (secrets.enc) is then encrypted again with the master key
• File permissions are restricted to owner-only (0600)

This double-encryption means even if an attacker obtains the encrypted vault file, they need both the master key and the individual secret name to recover any value.

Push (Upload)

1. The CLI collects your tracked configs, env files, and repo metadata
2. Everything is serialized to JSON locally
3. The JSON is encrypted with your master password-derived key
4. The ciphertext is base64-encoded and sent to our API
5. Our server stores the opaque blob in Cloudflare R2 storage

Pull (Download)

1. The CLI requests the latest encrypted state from our API
2. Our server returns the encrypted blob (it cannot read it)
3. The CLI decrypts the blob locally using your master password
4. Configs and env files are restored to their original locations

Infrastructure

• Hosting: Cloudflare Workers (edge computing, no persistent servers to compromise)
• Database: Cloudflare D1 (encrypted at rest by Cloudflare)
• Storage: Cloudflare R2 (encrypted at rest, stores only your ciphertext)
• Transport: TLS 1.3 enforced on all connections

Authentication

• Passwords: Hashed with bcrypt (cost factor 10) — never stored in plaintext
• Sessions: JWT tokens in httpOnly, secure, sameSite cookies (7-day expiry)
• API tokens: SHA-256 hashed before storage — we store only the hash, not the raw token
• CLI auth: Bearer tokens prefixed with cs_ for easy identification and rotation