Zanzibar

Distributed cryptographic protocol.

Overview

Run

To run the tests:

cargo test

To run the benchmarks:

cargo bench

To generate documentation:

cargo doc --open

Demo

To run a demo we need:

• A shared key
• 3 mix nodes
• 1 client

There's a key already configured in mix-node/config/crypto.json. However, the secret_key will be different for each node, this will be overriden with environment variables later.

Keys

• Participant 0: secret_key = "D7W4K_1QPjuoEQNsTeyWT92yHSPp67-sApmGksw9EQo"
• Participant 1: secret_key = "XGaup1prWoijF91au13Qv2OgqGjo-uE74szhzGbXUgw"
• Participant 2: secret_key = "qRekI7iFdtWeHbdJKc8JMOqNM67nCQTLwQA9BwFxlA4"

If you want to generate keys yourself (optional)

To generate a new set of keys:

# 3 participants with 2 minimum threshold
cargo run --bin gen_keys -- 2 3

Copy the resulting key_set into the crypto.json config file.

Running Mix Nodes

We can spin up the 3 mix nodes like so:

# For more detailed logs, run these before starting the servers:
# export RUST_LOG=info,mix_node=trace,tower_http=debug

# Participant 0
APP_CRYPTO__SECRET_KEY="D7W4K_1QPjuoEQNsTeyWT92yHSPp67-sApmGksw9EQo" \
APP_CRYPTO__WHOAMI="0" \
APP_APPLICATION__PORT="6000" \
cargo run --bin rest --release

# Participant 1
APP_CRYPTO__SECRET_KEY="XGaup1prWoijF91au13Qv2OgqGjo-uE74szhzGbXUgw" \
APP_CRYPTO__WHOAMI="1" \
APP_APPLICATION__PORT="6001" \
cargo run --bin rest --release

# Participant 2
APP_CRYPTO__SECRET_KEY="qRekI7iFdtWeHbdJKc8JMOqNM67nCQTLwQA9BwFxlA4" \
APP_CRYPTO__WHOAMI="2" \
APP_APPLICATION__PORT="6002" \
cargo run --bin rest --release

Running the Client

Now that the network of mix-nodes is up and running, we can run the client that will request a comparison:

# two codes of length 10
cargo run --example demo -- 10

# two codes of length 12800
cargo run --example demo -- 12800

Note: Because the servers are running on the same machine and the operations are very CPU heavy, the performance is not truly representative of a real-world deployment.

How it Works

The client:

1. Requests the public key to encrypt the codes (instead of hardcoding it)
2. Generates a random code with the given length and clones it (both codes will be identical)
3. Encrypts both codes and sends a request to "http://localhost:6000/hamming"
4. Since the codes are identical, the expected hamming distance is 0

Testing Threshold Decryption

To test threshold decryption:

1. Shutdown the mix-node on port 6002 and run the client again - it should still compute the hamming distance
2. Shutdown another mix-node (port 6001) - the network can no longer compute the hamming distance because the number of nodes is below the threshold, returning an error

The code for the client can be found at mix-node/examples/demo.