todo

• automated sudoku solver
• cache pk/vk
• clean up code
• bitcoin transaction stuff

circuit description for some NxN puzzle:

primary inputs: sodoku puzzle P, key commitment C, encrypted solution E

auxillary inputs: solution S, key K

properties:

• puzzle subset: S must be a subset of P (the solution must complete the puzzle)
• solution closure: S must be closed under rows, columns and groups of the solution (the solution must be correct)
• encryption correctness: E must be S encrypted with K (using a stream cipher produced from SHA256)
• solution commitment: C must be SHA256(K)

usage:

Alice produces puzzle P and sends Bob P and the zk-SNARK proving key. Bob finds a solution S for the puzzle and constructs K, C, and E. Bob constructs a Proof. Bob sends Alice (Proof, C, E). Alice verifies the proof. Alice sends a CLTV transaction over the blockchain to Bob with the added constraint that Bob must produce the preimage of C (aka K). After Bob redeems the TxOut, Alice uses K to decrypt E, producing S. If Bob does not redeem the TxOut, Alice recovers her value but does not obtain S.

todo:

• write better tests
• write interface for interacting with the snark