NIST FIPS 203 · ML-KEM-768 · AES-256-GCM

pqguard
Post-Quantum Encryption

Encrypt files with NIST-standardized algorithms that resist both classical and quantum computer attacks. One command. Quantum-safe.

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pqguard — post-quantum file encryption

$ pqguard keygen 🔐 Generating post-quantum keypair... ✅ Keypair generated: Public key: alice.pqg.pub Private key: alice.pqg.key $ pqguard encrypt secret.txt -r alice.pqg.pub 🔒 Encrypting 'secret.txt' with ML-KEM-768... Size: 1048576 bytes → 1048689 bytes (100.0%) KEM: ML-KEM-768 | Cipher: AES-256-GCM ✅ Encrypted → secret.pqg $ pqguard decrypt secret.pqg -k alice.pqg.key 🔓 Decrypting 'secret.pqg'... Decrypted: 1048576 bytes | Algorithm: ML-KEM-768 ✅ Decrypted → secret.txt

Why post-quantum?

Classical cryptography (RSA, ECDH) will be broken by quantum computers. "Harvest now, decrypt later" is happening today.

🔐

ML-KEM-768 (Kyber768)

NIST FIPS 203 — the post-quantum key encapsulation standard. 192-bit quantum security. Resists Shor's algorithm on quantum computers.

⚡

AES-256-GCM

Authenticated encryption with associated data. Industry-standard symmetric cipher. Quantum-resistant at 256-bit key size.

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HKDF-SHA256

Hierarchical key derivation from shared secrets. Each encryption uses unique salt for complete key separation.

🛡️

Harvest Now, Decrypt Later

Adversaries store encrypted data today to decrypt with future quantum computers. pqguard makes this impossible.

Algorithm Stack

Component	Algorithm	Standard	Security
Key Exchange	ML-KEM-768	NIST FIPS 203	192-bit quantum
Key Derivation	HKDF-SHA256	RFC 5869	128-bit
Symmetric Cipher	AES-256-GCM	NIST SP 800-38D	256-bit
Encoding	Base64	RFC 4648	—

How encryption works

Generate random salt + nonce

32-byte salt for key derivation, 12-byte nonce for AES-GCM. Unique per encryption.

ML-KEM-768 encapsulate

Generate shared secret + ciphertext using recipient's public key. Only they can recover the secret.

Derive symmetric key

HKDF-SHA256(shared_secret, salt) → 256-bit AES key. Domain-separated per file.

AES-256-GCM encrypt

Authenticated encryption of file contents. Tamper-evident ciphertext with 128-bit auth tag.

Write PQGR envelope

Magic bytes + version + KEM ciphertext + nonce + salt + encrypted data. Self-contained file.

Get started in 30 seconds

One command. Quantum-safe encryption.

# Install
$ cargo install pqguard

# Generate keypair
$ pqguard keygen
🔐 Generating post-quantum keypair...
✅ Keypair generated:
   Public key:  default.pqg.pub
   Private key: default.pqg.key

# Encrypt a file
$ pqguard encrypt document.pdf -r default.pqg.pub
🔒 Encrypting 'document.pdf' with ML-KEM-768...
✅ Encrypted → document.pqg

# Decrypt
$ pqguard decrypt document.pqg -k default.pqg.key
🔓 Decrypting 'document.pqg'...
✅ Decrypted → document.pdf
  

pqguardPost-Quantum Encryption