Zero-knowledge password manager
Security Model & Architecture
Comprehensive overview of how Passary protects your most sensitive data through zero-knowledge architecture and military-grade encryption.
Our Security Philosophy
Security isn't about promises—it's about mathematical guarantees. Passary is built on the principle that we should never have the ability to access your data, even if we wanted to, even if legally compelled.
This zero-knowledge architecture means your passwords are protected by cryptography, not trust. We've eliminated single points of failure and designed a system where you alone hold the keys to your vault.
Security Architecture
Local-Only Storage
Your encrypted vault resides exclusively on your device. No cloud storage, no servers, noSync—just your data, your device, your control.
Client-Side Encryption
All cryptographic operations execute in your browser. Encryption, decryption, key derivation—everything stays local.
Zero-Knowledge Design
We mathematically cannot access your master password or decrypted vault data. It's not a policy—it's cryptographic certainty.
Privacy by Design
No accounts, no analytics, no tracking. Check your network tab—zero requests during vault operations.
Cryptographic Implementation
Passary uses industry-leading cryptographic algorithms with carefully chosen parameters to ensure maximum security.
Argon2id Key Derivation
Winner of the Password Hashing Competition. Argon2id is a memory-hard function that derives your encryption key from your master password.
Memory
64 MB
Iterations
3
Output
256 bits
AES-256-GCM Encryption
Military-grade authenticated encryption. Used by the US government for TOP SECRET information. Provides both confidentiality and integrity.
- 256-bit keys — Quantum-resistant security
- GCM mode — AEAD (Authenticated Encryption with Associated Data)
- Hardware-accelerated — AES-NI instructions on modern CPUs
Web Crypto API
All cryptographic operations use the browser's native Web Crypto API—a W3C standard that provides secure, constant-time implementations resistant to timing attacks.
Want the technical details? Visit our Encryption Details page for algorithm specifications, parameters, implementation code, and security analysis.
Threat Model & Protection
Understanding what threats Passary protects against—and what remains your responsibility.
Protected Threats
Server Compromise
If our website infrastructure is breached, attackers gain nothing—your vault isn't on our servers.
Legal Demands
Even if compelled by law enforcement or government, we genuinely cannot provide vault access.
Insider Threats
Malicious employees or compromised admin accounts cannot access user vaults.
Mass Surveillance
No centralized database to monitor or intercept—all data is local and encrypted.
Network Eavesdropping
Vault data never transmitted over the network—nothing to intercept.
Brute-Force Attacks
Argon2id + AES-256 makes brute-forcing computationally infeasible (billions of years).
Your Responsibility
- Device Security: Protect your device with strong passwords, full-disk encryption, and security updates
- Master Password: Choose a strong, unique master password and never reuse it elsewhere
- Backups: Regularly export and back up your vault file to prevent data loss
- Browser Security: Keep your browser updated and avoid malicious extensions
- Phishing: Always verify you're on passary.com before entering your master password
Attack Resistance
Brute-Force Resistance
With AES-256, there are 2^256 possible keys ≈ 1.15 × 10^77 combinations.
Quantum Resistance
Grover's algorithm reduces AES-256 to effective 128-bit security—still far beyond brute-force reach.
- AES-256 chosen for quantum resistance
- Argon2id memory-hardness also quantum-resistant
- 128-bit effective security = 2^128 operations still impossible
Side-Channel Protection
Web Crypto API and Argon2id designed to resist timing and cache-based attacks.
- Constant-time cryptographic operations
- Argon2id hybrid mode prevents cache-timing leaks
- Browser sandboxing limits attack surface
Password Cracking Defense
Argon2id's memory-hard design makes GPU/ASIC attacks economically infeasible.
- 64MB memory requirement per attempt
- Unique salt prevents rainbow table attacks
- Parallel cracking limited by memory bandwidth
Trust Model
Understanding what you must trust—and what you don't need to trust—when using Passary.
What You Don't Need to Trust
✓ Passary's servers
Your vault never touches our infrastructure
✓ Our administrators
No access to your encrypted data or keys
✓ Network security
Vault data never transmitted over network
✓ Cloud providers
No cloud storage or third-party services
What You Must Trust
→ Your browser
Crypto operations run in your browser environment
→ Your device
Vault stored locally; device security crucial
→ JavaScript delivery
Code served from passary.com must be authentic
→ Cryptographic libraries
Web Crypto API and Argon2 implementation
Future: Open Source & Reproducible Builds
We plan to open-source Passary and provide reproducible builds, allowing you to verify the code running in your browser matches our public repository. This will minimize trust requirements further.
Verify Our Claims
Don't just trust us—verify our zero-knowledge and local-first architecture yourself.
Network Inspection
Open your browser's DevTools → Network tab while using your vault. You'll see zero requests to external servers during vault operations.
Local Storage Check
Open DevTools → Application → IndexedDB. Your encrypted vault is stored locally—looks like random gibberish without your master password.
Offline Test
Load Passary, then disconnect from the internet. Your vault still works fully—proof that it's entirely local-first.
Source Code Review (Planned)
Our code will be open source, allowing security researchers to audit our cryptographic implementation.
Security Model Comparison
| Security Aspect | Passary (Zero-Knowledge) | Cloud Password Manager |
|---|---|---|
| Provider can access passwords | ✗ Impossible | ✓ Technically possible |
| Server breach impact | ✓ Zero impact | ⚠ High risk |
| Legal/govt. data request | ✓ Cannot comply | ⚠ Must hand over data |
| Password recovery | ✗ Not possible | ✓ Email reset available |
| Trust requirement | ✓ Minimal | ⚠ Must trust provider |
| Data location | Your device only | Provider's cloud |
| Backup responsibility | ⚠ User manages | ✓ Automatic |