Your family's financial information is personal. It includes your investments, assets, insurance policies, important documents, and account credentials.
Before trusting an app with this data, you should know exactly how it is protected.
Passbook is built around a simple principle: your financial data should remain private, encrypted, and under your control.
Here is how that security architecture works in practice.
Your data is encrypted on your device and in Google Drive
Passbook encrypts your financial database locally on your device before anything leaves your machine. When your data syncs to your personal Google Drive, the backup remains completely encrypted.
This means your financial information is never stored as readable text on your computer or in Google Drive. Google stores only the encrypted backup file.
Strong encryption algorithms protect your information
Passbook relies on established, peer-reviewed cryptographic standards rather than proprietary methods:
Argon2id derives a cryptographic key from your Master Password. It is deliberately designed to be computationally expensive, protecting against brute-force password guessing even if an attacker obtains the encrypted file.
ChaCha20-Poly1305 encrypts your data and authenticates it simultaneously. Encryption keeps unauthorized parties from reading the contents, while authentication ensures any tampering or file corruption is immediately detected.
Your encryption keys are protected by hardware security
Encryption is only as strong as the protection around its keys. Passbook uses your device's native hardware security facilities to protect your encryption keys.
On supported Macs, key storage uses Apple's Secure Enclave; on Windows, it uses the Trusted Platform Module (TPM) alongside native operating-system keychains.
Your Master Password is never stored on Passbook's servers, and Passbook never uploads your encryption keys to a central database.
Passbook has no central database holding your financial data
Passbook processes your financial information locally on your computer. It does not maintain a central database of users' financial portfolios or asset records.
Your encrypted backup goes directly to your personal Google Drive. Your financial portfolio data never passes through Passbook's servers—not even in encrypted form.
Passbook's servers handle limited account and subscription details, but never your financial records.
This architecture eliminates the risk of your data being exposed in a central server breach.
Secure read-only access in the browser
You can access a read-only view of your financial records through the Passbook web app without routing your portfolio through Passbook's servers.
The web app retrieves your encrypted backup directly from your Google Drive and decrypts it locally inside your browser's memory using your Master Password.
The decrypted data remains isolated in your browser session and is completely cleared when you sign out or close the tab.
Master Password and account recovery
Because Passbook operates without a central database, we do not store your Master Password and cannot reset or retrieve it for you.
If you need to reset your password, you can do so using one of your active devices through supported hardware authentication.
However, if you lose your Master Password and lose access to all your configured devices, your encrypted backup cannot be recovered.
What does this mean for you?
Passbook combines local encryption, hardware-backed key protection, and direct Google Drive sync to deliver a zero-knowledge architecture where only you hold the keys to your financial life.
While no software system can eliminate all external risks—such as malware on an unpatched computer or compromised Google account credentials—Passbook's approach ensures that a breach of our company servers will never compromise your financial data.