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