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QuantaMail

Post-Quantum Encrypted Email, Built From Scratch

Python Flask SQLite Gmail API bcrypt LWE NIST PQC License: MIT

Encrypt your emails with an algorithm that even quantum computers can't break.

Features · How It Works · Architecture · Run Locally · Security


📸 Screenshots

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✨ Features

  • 🔒 LWE post-quantum encryption — message body encrypted before it ever leaves your machine
  • 📬 Gmail integration — send via SMTP, read via Gmail API OAuth 2.0
  • 🧑‍💼 User accounts — sign up, log in, sessions managed securely
  • 🛡 bcrypt password hashing — passwords never stored in plaintext
  • 🗄 Zero-setup database — SQLite, no database server needed
  • 🌑 Dark quantum UI — custom-built dark theme with animated grid background
  • 📦 Portable — runs on any machine with Python 3.10+

🔬 How the Encryption Works

Based on independent research into lattice-based cryptography and post-quantum security.

The Problem With Today's Encryption

Every email you send with standard Gmail is encrypted in transit using RSA or Elliptic Curve Cryptography (ECC). These algorithms are secure today — but they have a fatal flaw: their security rests on how hard it is for a computer to factor large numbers or solve the discrete logarithm problem.

In 1994, mathematician Peter Shor proved that a sufficiently powerful quantum computer could solve both of these problems in polynomial time — making RSA and ECC completely breakable.

Classical computer attacking RSA-2048:
  Time estimate: ~300 trillion years ✅ Safe

Quantum computer (Shor's algorithm) attacking RSA-2048:
  Time estimate: ~hours ❌ Completely broken

QuantaMail uses a fundamentally different class of cryptography that remains hard even for quantum computers.


Learning With Errors (LWE)

LWE is a lattice-based cryptographic primitive first formalised by Oded Regev in 2005. Its security is based on the hardness of a completely different problem — one that has no known quantum speedup.

The core idea: Given a system of linear equations with small random errors added to each result, it is computationally infeasible to recover the original secret — even with a quantum computer.

Without errors (easy to solve — just linear algebra):
  a₁·s = b₁
  a₂·s = b₂
  a₃·s = b₃

With errors added (hard — this is LWE):
  a₁·s + e₁ = b₁   where e₁ ∈ {0, 1}
  a₂·s + e₂ = b₂   where e₂ ∈ {0, 1}
  a₃·s + e₃ = b₃   where e₃ ∈ {0, 1}

The noise terms e are tiny, but they destroy the clean linear structure that would let an attacker solve the system. No known classical or quantum algorithm can efficiently recover s.


QuantaMail's LWE Implementation

Key generation:

Parameters:
  n = 1024       (vector dimension)
  q = 65536      (modulus, 2¹⁶)
  e ∈ {0, 1}     (small error values)

1. Sample random public vector:   a ← Zqⁿ
2. Sample secret key:             s ← Zqⁿ
3. Sample error vector:           e ← {0,1}ⁿ
4. Compute public key:            b = (a·s + e) mod q

Encrypting one bit m (0 or 1):

1. Sample ephemeral vector:   r ← {0,1}ⁿ
2. Compute ciphertext pair:
     c₁ = r·a         mod q
     c₂ = r·b + m·(q/2)  mod q

Decrypting:

1. Compute:   v = c₂ - c₁·s   mod q
2. Round:     if |v - 0| < |v - q/2|  → m = 0
              else                    → m = 1

The rounding works because the error e is small relative to q/2. The noise shifts v slightly away from 0 or q/2, but not enough to push it past the halfway threshold — so we can always recover the correct bit.

For full messages, each character is encoded as 8 bits, each bit is encrypted independently, and messages longer than 128 characters are split into blocks:

"Hello, World!" (13 chars)
       ↓
  104 bits (13 × 8)
       ↓
  104 separate LWE encryptions
       ↓
  c1[104], c2[104]  — the ciphertext
       ↓
  Transmitted as a Python dict string over email body

Why LWE Is Quantum-Resistant

The reason LWE resists quantum attacks comes down to the geometry of high-dimensional lattices. Finding the secret s in an LWE instance is equivalent to solving the Shortest Vector Problem (SVP) in a lattice — finding the shortest non-zero vector in a high-dimensional grid.

Security comparison across attack models:

Algorithm        Classical Attack    Quantum Attack (Grover/Shor)
─────────────────────────────────────────────────────────────────
RSA-2048         ~2¹¹² ops          ~polynomial  ← BROKEN
ECC-256          ~2¹²⁸ ops          ~polynomial  ← BROKEN
AES-256          ~2²⁵⁶ ops          ~2¹²⁸ ops    ✓ Still ok
LWE (n=1024)     ~2¹⁰⁰ ops          ~2¹⁰⁰ ops    ✓ Quantum-safe
─────────────────────────────────────────────────────────────────

For LWE, the best known quantum algorithm offers no asymptotic advantage over classical attacks — the hardness of the lattice problem is preserved.


Performance Profile

Encryption is more expensive than RSA for short messages, but scales predictably. Here's the approximate cost per character on a standard laptop CPU:

Encryption time vs message length (approx, Python, n=1024):

  10 chars  | ████░░░░░░░░░░░░░░░░  ~0.3s
  50 chars  | ████████░░░░░░░░░░░░  ~1.4s
 100 chars  | ████████████░░░░░░░░  ~2.8s
 200 chars  | ████████████████░░░░  ~5.5s  (crosses block boundary)
 500 chars  | ████████████████████  ~14s

Note: This implementation is pure Python for transparency/education.
A production system (e.g. CRYSTALS-Kyber in C) runs ~1000× faster.

Security margin vs key size:

LWE Dimension (n)  |  Security Level   |  Used In
───────────────────────────────────────────────────────
     256           |   ~80-bit         |  Lightweight IoT
     512           |   ~100-bit        |  General use
    1024  ◄ours    |   ~128-bit        |  QuantaMail
    2048           |   ~192-bit        |  CRYSTALS-Kyber (NIST)
    4096           |   ~256-bit        |  High-security applications

NIST Post-Quantum Cryptography Standardisation

In 2022, NIST completed a 6-year evaluation of post-quantum cryptographic algorithms. The primary encryption standard they selected was CRYSTALS-Kyber — a Key Encapsulation Mechanism (KEM) built directly on top of LWE (specifically a variant called Module-LWE).

NIST PQC Standards (2024):

  Encryption/KEM:
    ✅ CRYSTALS-Kyber (ML-KEM)   ← Module-LWE — same family as QuantaMail

  Digital Signatures:
    ✅ CRYSTALS-Dilithium (ML-DSA)
    ✅ FALCON (FN-DSA)
    ✅ SPHINCS+ (SLH-DSA)

  Evaluated but not selected:
    ✗ NTRU        (lattice, different problem)
    ✗ Classic McEliece  (code-based)
    ✗ SIKE        (isogeny-based, later broken)

QuantaMail's algorithm.py implements the foundational LWE scheme that underpins the NIST standard — built from scratch to demonstrate understanding of the underlying mathematics.


🏗 Architecture

┌─────────────────────────────────────────────────────────────┐
│                     Browser / Client                        │
└─────────────────────────┬───────────────────────────────────┘
                          │  HTTP
┌─────────────────────────▼───────────────────────────────────┐
│                    Flask (app.py)                           │
│                                                             │
│  GET /          → login.html                               │
│  POST /login    → verify_user() → session                  │
│  GET /dashboard → fetch + decrypt → dashboard.html         │
│  POST /send_mail→ encrypt → SMTP send                      │
│  GET /logout    → session.clear()                          │
└──────┬──────────────────┬──────────────────┬───────────────┘
       │                  │                  │
┌──────▼──────┐  ┌────────▼───────┐  ┌──────▼──────────────┐
│ database.py │  │ algorithm.py   │  │  gmail_service.py   │
│             │  │                │  │                     │
│ SQLite      │  │ LWE Encrypt    │  │  Gmail OAuth 2.0    │
│ bcrypt      │  │ LWE Decrypt    │  │  Token caching      │
│ users table │  │ Block chunking │  │  Message parsing    │
└─────────────┘  └────────┬───────┘  └──────────────────── ┘
                          │
                 ┌────────▼───────┐
                 │    smtp.py     │
                 │                │
                 │ Gmail SMTP     │
                 │ .env creds     │
                 └────────────────┘

File structure:

quantamail/
├── app.py               ← Flask app, all routes
├── algorithm.py         ← LWE post-quantum encryption
├── database.py          ← SQLite + bcrypt user management
├── gmail_service.py     ← Gmail API OAuth wrapper
├── smtp.py              ← Email sending via SMTP
├── requirements.txt     ← Python dependencies
├── .env.example         ← Secrets template (copy → .env)
├── .gitignore
├── templates/
│   ├── login.html
│   ├── signup.html
│   └── dashboard.html
└── static/
    ├── style.css        ← Auth pages (dark theme)
    ├── dashboard.css    ← Dashboard layout
    └── 2.jpeg           ← Logo

🚀 Running Locally

Prerequisites

1 — Clone & create virtual environment

git clone https://github.com/YOUR_USERNAME/quantamail.git
cd quantamail

python3 -m venv venv
source venv/bin/activate        # Windows: venv\Scripts\activate

2 — Install dependencies

pip install -r requirements.txt

3 — Configure environment

cp .env.example .env

Open .env and fill in:

SECRET_KEY=any-long-random-string
SMTP_USER=your-gmail@gmail.com
SMTP_PASSWORD=your-app-password

4 — Run

python app.py

Visit http://localhost:8000

5 — (Optional) Enable inbox reading

To read encrypted emails in the inbox tab, you need a Gmail API credential:

  1. Go to Google Cloud Console → create a project
  2. Enable the Gmail API
  3. Create OAuth 2.0 credentials → download as credentials.json
  4. Place credentials.json in the project root
  5. On first inbox load, a browser window will open to authenticate — after that, the token is cached

🛡 Security

Layer Implementation
Message encryption LWE (Learning With Errors), n=1024, q=2¹⁶
Password storage bcrypt (cost factor 12)
Session management Flask server-side sessions with secret key
SMTP credentials Environment variables via .env, never hardcoded
Gmail OAuth Token cached in token.pickle, excluded from Git
.gitignore Excludes .env, credentials.json, token.pickle, venv/

Note on the LWE parameters: The parameters n=1024, q=65536 provide approximately 128-bit classical security. This implementation is written in pure Python for readability and demonstration. A production deployment would use a compiled library like liboqs implementing CRYSTALS-Kyber.


📦 Tech Stack

Layer Technology
Language Python 3.10+
Web framework Flask 3.0
Cryptography Custom LWE (algorithm.py)
Database SQLite via sqlite3
Password hashing bcrypt
Email send smtplib (Gmail SMTP)
Email read Google Gmail API v1 (OAuth 2.0)
HTML parsing BeautifulSoup4
Frontend HTML5, CSS3 (custom dark theme)
Secrets management python-dotenv

📄 License

MIT — see LICENSE


Built to explore post-quantum cryptography applied to real-world communication. The encryption algorithm in this project belongs to the same mathematical family as the 2024 NIST post-quantum standard.

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