Biometric PDF Password Vault — Open Encrypted Statements with Your Fingerprint

The Monthly Password Friction

Financial institutions, insurance providers, and employers frequently protect PDF statements with passwords derived from combinations of your tax ID, date of birth, name, and account numbers.

Opening recurring monthly documents often requires repetitive password entry or referencing stored notes.

MiygaL PDF addresses this with the Biometric PDF Password Vault: enter the password once, verify your fingerprint, and unlock future matching documents with a touch.

Essential Security Principle

MiygaL PDF is a secure password vault, NOT a password cracker. You must know and enter the authorized password the first time you open the document. MiygaL securely remembers your authorized passwords so you do not need to re-type them; it does not crack, bypass, or recover unknown passwords.

How the Biometric Password Vault Works

[ Encrypted PDF Received ]
            │
            ▼
[ User Enters Valid Password Once ] ──► [ Saved to Android Keystore (AES-256) ]
            │
            ▼
[ Future Opens of Matching Document ] ──► [ Verify Fingerprint / Biometrics ]
                                                    │
                                                    ▼
                                    [ Unlocked in Device Memory ]

1. Does the User Need to Know the Original Password?

Yes. You must supply the correct, legitimate password on the initial open. MiygaL validates the password against the document's encryption dictionary. Once verified, you can choose to save it in your private Vault.

2. What Does Biometric Authentication Do?

When opening an encrypted document linked to a saved vault credential, MiygaL calls Android's native BiometricPrompt API. When you authenticate using your fingerprint (or device biometrics), the operating system authorizes the retrieval of the stored credential from the Android Keystore. The app then decrypts the document in memory without displaying the plain password on screen.

3. Where Are Saved Passwords Stored?

Saved passwords are encrypted using AES-256 encryption and stored locally inside secure app storage (flutter_secure_storage), backed by the Android Keystore System utilizing hardware-backed security (such as the device's Trusted Execution Environment or StrongBox keymaster where available). Passwords are never written to plain text files, never included in unencrypted backups, and never transmitted to the cloud.

4. Does This Feature Work Offline?

100% offline. All cryptographic operations and biometric verifications execute locally through Android OS hardware security facilities without contacting remote authentication servers.

5. Password Vault vs. Removing PDF Encryption

It is important to understand the difference between these two capabilities:

• Biometric Password Vault: The original PDF file remains encrypted on disk. Anyone accessing your device storage or copying the file still requires the password. Only you can unlock it using biometric verification in MiygaL.
• Removing PDF Encryption: Exports a separate, unencrypted duplicate file (<filename>_unl.pdf) with password requirements stripped.

User Perspective Use Cases

1. Working Professionals

Managing monthly salary slips, health insurance e-cards, and retirement statements without searching through password cheat sheets or old emails.

2. Investors & Financial Planners

Reviewing daily brokerage contract notes, mutual fund statements, and tax vouchers from multiple institutions in one seamless reading session.

3. Homeowners & Utility Payers

Accessing electricity bills, broadband invoices, and municipal tax receipts protected by customer account numbers with an effortless fingerprint touch.

Capability Comparison: Password Storage Approaches