BattleZips-Halo2

Code

x86_64-unknown-linux-gnu was the development target for this codebase.

Unit test the board and shot circuits

cargo test

Build the wasm for (BattleZipV2-Frontend)[https://github.com/BattleZips/BattleZipsV2-Frontend]:

cargo build --release --target=wasm32-unknown-unknown
# find the outputted wasm artifacts
ls ./target/wasm32-unknown-unknown/release

Circuits

Board Circuit

Inputs array of 10 private ship commitments corresponding to [H5, V5, H4, V4, H3a, V3a, H3b, V3b, H2, V2]
For each pair ex: (H5, V5) constrain at least one of the values to be equal to 0
Constrained binary decomposition of all ship commitments into bits
For each pair of decomposed bits, constrain individual ship placement via PlacementChip
Once all placements pass, constrained transposition all decomposed ship commitments into one decomposed board commitment
Constrained binary recomposition of board commitment bits into a single board state value
Constrained pedersen commitment of board state into board commitment
Publicly export board commitment from zero knowledge proof

Shot Circuit

Inputs board_state, board_commitment, shot_commitment, hit_assertion
- board_state - private 100-bit number (constrained in Board Circuit) with flipped bits representing shot placements
- board_commitment - the pedersen comitment of board_state
- shot_commitment - public 100-bit number constrained to have only 1 bit flipped representing serialized shot coordinate
- hit_assertion - public boolean statement on whether shot_commitment's flipped bit is also flipped in board_state
Constrains hit_assertion to be equal to either 0 or 1
Constrains shot_commitment to have exactly 1 flipped (true) bit when decomposed into binary
Constrains hit_assertion to be equal to the number of rows where shot_commitment and board_state both have a flipped bit
Constrains the proper computation of the Pedersen commitment of board_state
Constrains board_commitment input advice to equal to the computed pedersen commitment of board_state
Publicly export board_commitment, shot_commitment, hit_assertion from the zero knowledge proof

License

BattleZipsV2 is license under GNU GPLv3. Go nuts.

Contact Project Maintainer

Join the BattleZips Discord channel

Motivation

Battleships is an adversarial, two-player board game centered around a hidden information mechanic. BattleZips-Halo2 demonstrates how one constrains computations for a Battleship game with the intent that developers can extrapolate their own projects in the zcash/Halo2 proving scheme.

On ZK State Channels

Halo2 recursion eluded us. After quickly putting together a PCD-based recursion prototype in Plonky2, we received feedback that IVC-based accumulation would be sufficient for this case. We will revisit in the future with the KZG fork.

Todo:

figure out KZG fork
determine how to make circuit more efficient
determine how to use accumulation to build IVC state channel

BattleZips / BattleZips-Halo2