ZKP / Commitment Guarantees

The buy flow binds custody proofs to contract issuance.

Bound tuple

• witness_proof: public commitment for contract ID
• encrypted_witness_secret: seller-targeted encrypted custody secret
• witness_zkp: signed commitment payload/hash proof

Verification goals

• contract ID consistency
• commitment hash integrity
• signer binding to buyer identity
• seller-targeted encrypted secret integrity

Non-repudiation checkpoints

1. Buy request: immutable witness commitment recorded.
2. Accept request: seller acceptance recorded with signature proof.
3. Replace request: witness state proves ownership transfer.
4. Deliver request: requires currently valid seller-held witness secret.

Together, these block denial claims about acceptance and custody state.