Inference Receipts: Lightweight Cryptographic Commitment Chains for Auditable Generative AI

We introduce inference receipts—lightweight cryptographic commitment records generated during generative AI inference that bind model identity, sampling configuration, and output tokens into a tamper-evident artifact. Unlike zero-knowledge proof systems or trusted execution environments, inference receipts operate under an honest-emitter trust model analogous to Certificate Transparency: the emitter commits faithfully, and any deviation is detectable by third-party auditors. This design occupies a distinct point on the cost–trust Pareto frontier—negligible overhead and no specialized hardware, at the cost of weaker guarantees than cryptographic proofs.

We formalize three security properties (receipt binding, tamper detection, chain integrity) via game-based reductions to standard cryptographic assumptions (collision resistance, second-preimage resistance). We describe receipt granularity levels (per-session, per-forward-pass, and per-token), a four-phase orchestration pattern (PLAN, SENSE, DECIDE, PROVE) for bounded AI autonomy, and an oracle mode for opaque cloud models. Ten experiments spanning four model families (1.5B–72B parameters), three quantization levels, three cloud APIs, and three receipt granularity levels on consumer-grade hardware demonstrate: overhead below 0.006% of inference time even at per-token granularity with top-k logit hashing (decreasing to below 0.001% at 72B scale); O(1) amortized chain emission sustained to 10⁶ receipts at 168,860 receipts/sec; 100% tamper detection across 1,200 attempts with zero false positives; perfect within-quantization deterministic replay; and 96% claim recall with 100% chain integrity across 15 multi-step PLAN/SENSE/DECIDE/PROVE workflows, with an honest assessment of gate limitations at 7B model scale. All data, scripts, and a standalone verifier are provided as ancillary files.