Send secrets that even quantum computers can't break

PQ Secure is a zero-knowledge messaging platform that uses NIST-standardized post-quantum cryptography. Messages are encrypted in your browser the server never sees your keys or plaintext.

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ML-KEM-768 AES-256-GCM HKDF-SHA256 Zero-Knowledge No CDN Open Source Audited ★ Star on GitHub

🔒 Post-Quantum Encryption

Uses ML-KEM-768 (CRYSTALS-Kyber), the NIST-standardized key encapsulation mechanism. Your data is protected against both classical attacks and future quantum decryption.

📈 Zero Knowledge Architecture

Encryption and decryption happen entirely in your browser. The server stores only ciphertext data indistinguishable from random noise. We never see your keys or content.

🔗 One-Click Sharing

Every message generates a fresh keypair. The secret key is embedded directly in the share link. No pre-shared keys, no setup, no accounts required for basic use.

📄 File & Text Support

Encrypt text messages or files up to 10 MB. Optionally password-protect with AES-256-GCM + PBKDF2 (100k iterations). Support for combined text + file messages.

🕴 Self-Destructing Messages

Set a maximum view limit messages automatically self-destruct after being read. Combined with 7-day expiry, your data doesn't linger on the server.

🚀 No Dependencies

Zero third-party scripts, CDNs, or trackers. Cryptographic operations use the browser's Web Crypto API and WebAssembly. The PHP backend stores only opaque ciphertext.

Common use cases

📩

Share sensitive links & credentials

Send API keys, database passwords, or one-time access links with end-to-end post-quantum protection.

📝

Confidential documents

Encrypt legal documents, contracts, or financial records before sharing via any channel.

💬

Private replies

Enable reply capability to let recipients respond securely all encrypted end-to-end with post-quantum keys.

🛡

Harvest-now, decrypt-later protection

Post-quantum encryption ensures your data stays confidential even when quantum computers become available.

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What is post-quantum encryption?

Nearly all encryption on the internet today relies on RSA or elliptic-curve cryptography (ECC). These systems are secure against classical computers but will be broken by sufficiently powerful quantum computers using Shor's algorithm. Post-quantum cryptography uses mathematical problems that are believed to be hard for both classical and quantum computers.

PQ Secure uses ML-KEM-768 (formerly CRYSTALS-Kyber), the NIST-standardized post-quantum key encapsulation mechanism. It provides security roughly equivalent to AES-192 against quantum attackers.

Cryptographic chain

Every encrypted message passes through three layers:

ML-KEM-768 → HKDF-SHA256 → AES-256-GCM

ML-KEM-768 — Post-quantum key encapsulation. Generates a shared secret that only the intended recipient can recover.
HKDF-SHA256 — Derives a strong symmetric key from the shared secret with domain separation.
AES-256-GCM — Authenticated encryption of the actual message data.

How PQ Secure works

No pre-shared keys needed. Every encryption generates a fresh one-time ML-KEM-768 keypair. The secret key is embedded directly in the share link when the recipient opens it, their browser recovers the key from the URL and decrypts locally.

1 Sender Generates a one-time ML-KEM-768 keypair

2 Sender Encapsulates with the public key → derives an ML-KEM shared secret

3 Sender Encrypts the message with AES-256-GCM using the shared secret

4 Sender POSTs the ciphertext to the server → server stores it and returns an ID

5 Sender Builds a share link with the server ID and one-time secret key embedded

6 Recipient Opens the link → browser extracts the secret key from the URL

7 Recipient Requests ciphertext from the server → decapsulates with the secret key

8 Recipient Decrypts with AES-256-GCM → reads the plaintext

Zero-knowledge architecture

The server never sees your encryption keys, plaintext, or decrypted content. It stores only ciphertext data that is computationally indistinguishable from random noise. Even with full server access, an attacker gains nothing but unbreakable ciphertext.

Key generation, encryption, and decryption all happen in your browser
Cryptographic operations use the Web Crypto API and WebAssembly
The server stores only ciphertext with no access to keys
No third-party scripts, no CDN, no tracking

Why this matters

"Harvest now, decrypt later" attacks are already underway adversaries collect encrypted communications today, waiting for quantum computers to break them retroactively. Post-quantum cryptography protects your data against both current threats and future quantum attacks, especially critical for information with long-term sensitivity.

Technical details

Key encapsulation: ML-KEM-768 via liboqs WebAssembly
Symmetric encryption: AES-256-GCM via Web Crypto API
Key derivation: HKDF-SHA256 via Web Crypto API
File encryption: PBKDF2 (100k iterations) + AES-256-GCM
File size limit: 10 MB
Message expiry: 7 days (auto-cleaned)
Rate limit: 5 requests/minute/IP
Zero external dependencies no CDN, no third-party scripts

View source on GitHub · Open Source (MIT) · Independently audited