Turn Anything Into a Password

Transform memorable objects and photos into complex, cryptographically secure passwords. Your passwords come from your things—hence, Passthing. No master password to remember.

How It Works

Choose Your Passthing
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Choose Your Passthing

Select any physical object or choose a photo from your library. It could be your coffee mug, a book cover, or a plant.

Enroll & Generate
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Enroll & Generate

Frame your object in the viewfinder and capture multiple samples. Passthing generates a unique password based on the visual signature.

Retrieve Anytime
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Retrieve Anytime

When you need your password, simply point your camera at the same object or select the same photo. Your password is instantly retrieved and copied.

Built for Security

Perceptual Hashing

Advanced DCT-based perceptual hashing creates consistent signatures even with lighting or angle variations in camera mode.

Cryptographic Hashing

Image mode uses SHA-256 cryptographic hashing for exact-match security. Only the exact same image file will work.

Local-Only Storage

All data stays on your device. No internet required. No accounts. No data collection. Complete privacy.

Adjustable Strictness

Fine-tune matching sensitivity in camera mode. Balance convenience with security based on your needs.

A Different Approach

Passthing isn't trying to replace traditional password managers—it's a fundamentally different philosophy. Use it alongside your existing manager. If you need autofill, cloud sync, and access from anywhere, traditional managers are great. But if you want to add a zero-storage, zero-cloud solution where physical objects are your keys, Passthing is for you.

Frequently Asked Questions

What is perceptual hashing?

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Perceptual hashing is a technique that creates a "fingerprint" of an image based on its visual content rather than its exact pixels. Unlike traditional cryptographic hashes (where changing a single pixel completely changes the hash), perceptual hashes remain similar for images that look similar to the human eye.

Passthing uses DCT-based (Discrete Cosine Transform) perceptual hashing in Camera mode. When you capture your passthing, the image is downsampled to 32×32 pixels, converted to grayscale, and analyzed to extract visual patterns. This creates a 1,024-bit signature that stays consistent even when lighting changes, angles shift slightly, or the camera is different.

The result: You can point your iPhone at your coffee mug today and your iPad at the same mug tomorrow, and Passthing will recognize it as the same object—even though the exact pixels are different. This is what makes Camera mode practical for everyday use.

Is Passthing secure?

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Passthing uses proven cryptography (HMAC-SHA256, HKDF) to generate passwords deterministically from visual signatures. Your device secret never leaves your device, and passwords are generated on-demand—they don't exist in storage.

Security depends on your choices: Camera mode relies on perceptual hashing (Hamming distance matching with adjustable thresholds), so security depends on choosing visually unique objects. Image mode uses SHA-256 cryptographic hashing—security depends on library size and unpredictable image selection.

Passthing's security model is different from traditional password managers. To generate your passwords, an attacker needs your unlocked device AND knowledge of which objects are your passthings AND what those objects are passthings for AND how you framed them.

Which is more secure: Camera or Image mode?

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Both are secure with different tradeoffs. Camera mode uses perceptual hashing with adjustable strictness—more forgiving but depends on object uniqueness. Image mode uses cryptographic hashing requiring exact file matches—security depends on library size and unpredictable selection.

What happens if I lose my device?

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Passthing offers two backup methods to recover your enrollments on a new device:

  • Image Backup: Export all your enrollments to a photo using steganography. The data is invisibly embedded in the image, which you can store in your photo library or anywhere else. On a new device, simply restore from that image.
  • Device Transfer: Transfer your enrollments directly to another device over a secure local connection (both devices must be on the same WiFi network).

Both methods are accessible from Settings → Backup & Recovery. Without a backup, your passwords are only accessible through your device and physical objects, so creating backups is highly recommended.

Can I sync across devices?

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Yes, but there's no automatic cloud sync. Instead, Passthing offers two manual methods (both in Settings → Backup & Recovery):

  • Device Transfer: Directly transfer your enrollments to another device over a secure local connection. Perfect for setting up a new device.
  • Image Backup: Export to a photo that you can transfer however you like (AirDrop, encrypted messaging, etc.) and restore on any device.

No cloud sync means complete privacy—your data never leaves your control.

Can I use Passthing alongside my existing password manager?

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Absolutely! Many users keep Passthing for their most critical accounts (email, banking, master passwords) while using traditional managers for everyday logins. It's a great hybrid approach—use physics-based security for what matters most.

How do I choose the best passthing?

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In Camera mode, Passthing generates a 32×32 perceptual hash (1,024 bits) from your passthing. Security depends on three key factors:

  • Choose visually unique objects: A complex book cover or textured mug provides high entropy. A plain white wall or generic surface provides very low entropy, regardless of how you frame it.
  • Frame with detail: Capture rich visual information. Zooming too tight on a plain surface reduces uniqueness. Include texture, patterns, or distinctive features.
  • Set appropriate strictness: During enrollment, adjust the matching sensitivity. Higher strictness requires near-exact matches and is more secure. Lower strictness is more forgiving but increases collision risk.

The ROI zoom control helps when switching between devices with different cameras—not for security tuning. Focus on choosing unique, textured objects for the strongest security.

How many passthings can I create?

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There's no limit. Create as many passthings as you need for different accounts and services.

What if I lose my passthing?

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Unfortunately, nothing can be done. Passthing generates passwords from your physical objects—no backup, no recovery, no "forgot password" link. If you lose your passthing, you lose access to that password. Some things aren't meant to last forever.

This is by design. The password is mathematically derived from your passthing and device secret. Without the passthing, the password cannot be recreated. Consider backing up important account recovery codes separately, or use multiple passthings for critical accounts.