Secure Seed-Based Messaging

A seed-driven “book cipher” that hides your message in a deterministic pseudo-random text stream. Instead of sending encrypted files, you share a short hex pointer plus an encrypted phrase. With the same seed, the recipient regenerates just the right block of text, forces in the phrase, and extracts it.

---

How It Works

1. Agree on a seed
   You and your correspondent pick a secret string (the seed).

2. Generate text blocks

   • Each block (default 1024 characters) is created by hashing seed + block_index.
   • A pseudo-random generator uses that hash to produce the block on demand.

3. Map phrase to location

   • Hash phrase + seed to pick a block index and offset within it.
   • Compute a numeric location = block_index * block_size + offset.

4. Create an opaque pointer

   • XOR that location with a 64-bit key derived from the seed hash.
   • Encode the result in hex.

5. Encrypt the phrase

   • XOR each byte of your phrase with a repeating key from SHA-256(seed).
   • Convert to hex and append after the pointer, separated by :.

6. Retrieve the message

   • Split the pointer and encrypted phrase by :.
   • Reverse the XOR on the location to get block_index and offset.
   • Regenerate that block, overwrite it with the decrypted phrase, and extract your message.

---

Installation

Use the provided scripts to install Python and Tkinter dependencies.

Linux or macOS

./install.sh            # install dependencies
./install.sh --dry-run  # show commands without executing

Windows

Run the PowerShell script:

.\install.ps1
# or
.\install.ps1 -DryRun  # show commands without executing

---

Graphical Interface

Run the simple Tkinter GUI to search for a phrase or decode a pointer:

python gui.py

---

Requirements
Python 3.7 or later
Uses only standard library modules (hashlib, random, etc.)

License
All rights reserved. See LICENSE.