POW-Lock Encryption

POW-Lock Encryption is a proof-of-work based encryption system designed to ensure that the client performs significant computational work to decrypt data encrypted by the server. The server performs minimal work, making it efficient for scenarios where the server needs to offload computational effort to the client.

Features

• Minimal Server Work: The server quickly encrypts data using a symmetric key derived from a computational puzzle.
• Client-Side Proof-of-Work: The client must solve a puzzle to derive the symmetric key and decrypt the data.
• Configurable Difficulty: The difficulty of the puzzle can be adjusted to control the computational effort required by the client.
• POW-Lock Chain: An alternative implementation that mitigates parallel processing by requiring the client to solve a series of sequential puzzles, where each solution is dependent on the previous one. This approach is safer against parallel processing but may theoretically be less efficient than the original implementation. This is the recommended implementation.

How It Works

1. Chained Proof-of-Work Implementation

In this more advanced version, the client must solve a series of proof-of-work puzzles in sequence, where each solution depends on the result of the previous step. This makes it harder for the client to optimize the solve process.

Server Setup:

• The server generates a random nonce and selects multiple random starting points within the solution space (for each chain step).
• For each step, the server finds a solution that meets the specified difficulty and uses the hash of the solution to generate the nonce for the next step (solution chaining).
• After the final step, the last solution is used as the symmetric key to encrypt the data.
• The server provides the client with the initial nonce, the encrypted data, and a hash of each solution in the chain.

Client Solve:

• The client receives the initial nonce, the encrypted data, and the hash chain (hash of each solution in the series).
• It performs a sequential search to find the correct solution for each step, where the result of one step is used as the nonce for the next step.
• Once the client finds the final solution, it uses this as the symmetric key to decrypt the data.

3. Performance:
   • On average, the server creates the puzzle 10 times faster than the client resolves them at the default settings. This ensures that the server's workload is minimal while the client performs significant computational work.
   • Due to the random nature, it is possible for the client to solve it faster than the server, although it's rare, and the POW-Lock chain mitigates this.

2. Single Proof-of-Work Implementation

In this simpler implementation, the client performs a single computational task to decrypt the data.

Server Setup:

• The server generates a random nonce and selects a random starting point within a defined solution space.
• It finds a solution that meets a specified difficulty requirement and uses this solution as a symmetric key to encrypt the data.
• The server provides the client with the nonce, encrypted data, and a hash of the solution.

Client Solve:

• The client receives the nonce, encrypted data, and the hash of the solution.
• It performs computational work to find the solution that matches the hash by iterating through possible solutions.
• Once the correct solution is found, the client uses it as a symmetric key to decrypt the data.

Usage

Prerequisites

• Python 3.x
• cryptography library (optional, used for Fernet sym encryption in the example)

Installation

1. Clone the repository:

   git clone https://github.com/Silenttttttt/pow-lock-encryption.git
   cd pow-lock-encryption

2. Install the required Python packages:

   pip install cryptography

Running the Code

1. Open work_lock_chain.py and adjust the difficulty, max_solution, and solution_number parameters as needed.
2. Run the script:

   python work_lock_chain.py

Configuration

• Difficulty: Adjust the difficulty parameter to control the number of leading zeros required in the hash. I recommend leaving it at 4, because the time complexity increases exponentially O(2^k) and becomes nearly impossible for the client. To properly adjust the difficulty, read below.

• Max Solution: Set the max_solution parameter to define the upper bound for the solution space. The default value is genrally is recommended. This should be the value changed to increase the difficulty, due to its linear impact on the resolve time. Or the solution_number as well, for the chain implementation.

• Solution Number: For the pow-lock chain implementation, set the solution_number to define the number of sequential solutions required. This parameter can be experimented with, but a default of 5 is recommended. It should also be linear.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Contributing

Contributions are welcome! Please open an issue or submit a pull request for any improvements or bug fixes, or simply contact me directly.