zkTempo.sol

ZK-verified Tempo finality, settled on Solana.

zkTempo.sol is a cross-VM settlement primitive: a zero-knowledge light client that proves Tempo block finality and makes those proofs verifiable inside Solana programs. Downstream consumers — payment session protocols, cross-chain intent settlement, agent commerce rails — can confirm on Solana that a fact about Tempo is true (e.g. a PaymentIntent was emitted and finalized) without trusting a bridge operator, oracle, or multisig committee.

Status

Draft — v0.1.0-rfc.1. Pre-implementation. No reference code, no testnet deployment. Specs are subject to breaking change until v0.1.0 final.

Why

Cross-chain finality attestation today depends on social trust:

• Multisig bridges (Wormhole, LayerZero) trust a set of guardians.
• Oracle networks (Chainlink CCIP) trust a permissioned node committee.
• Optimistic bridges trust that someone will challenge a fraudulent claim within the window.

zkTempo.sol replaces social trust with cryptographic proof. A Solana program can verify Tempo finality from a ~200-byte Groth16 proof using alt_bn128 syscalls, with no external attestation required.

Architecture

   Tempo                ZK Prover (off-chain)         Solana
 ┌─────────┐         ┌──────────────────────┐      ┌────────────────┐
 │ Simplex │  cert   │ Tempo light client   │ proof│ zkTempo        │
 │ BFT     ├────────►│ inside SP1 zkVM      ├─────►│ verifier (PDA) │
 │ finality│         │ Groth16 wrap (BN254) │      │ alt_bn128      │
 └─────────┘         └──────────────────────┘      └────────┬───────┘
                                                            │
                                                            ▼
                                                   ┌────────────────┐
                                                   │ state root PDA │
                                                   │ + Merkle proof │
                                                   │ inclusion API  │
                                                   └────────────────┘

Three components:

• Light client — a no_std Rust crate that verifies Simplex BFT finality certificates against a known validator set. Deterministic, no I/O.
• Prover — an SP1 program that wraps the light client and produces a Groth16 proof per finalized block, plus an off-chain operator that drives proof generation.
• Verifier — a Solana Anchor program that checks the Groth16 proof via alt_bn128 syscalls and persists (slot, state_root) to a PDA. Downstream programs read this PDA to verify storage proofs.

Scope

In scope:

• Wire format for finality proofs (public inputs, version bytes, canonical encoding).
• Solana verifier program interface and state account layout.
• Light client protocol: initialization, finality updates, validator-set transitions.
• Composition patterns with mppsol_cpi for cross-VM payment settlement.
• Threat model: validator-set rotation, replay protection, cluster confusion.

Out of scope:

• General-purpose EVM→Solana state proving — zkTempo.sol is specific to Tempo's Simplex consensus. Other Reth-based L1s require separate consensus implementations.
• Asset bridging — zkTempo.sol proves finality only. Token semantics are downstream concerns.
• Liveness guarantees — proofs must be produced by an external operator; the verifier is permissionless to call but does not guarantee timely updates.

Specs

Document	Purpose
spec/light-client.md	Simplex finality verification rules; certificate format; validator-set transitions
spec/prover.md	SP1 program contract; input/output layout; Groth16 wrapping
spec/verifier.md	Solana program interface; verification key; state account PDA layout
spec/composition.md	Patterns for downstream programs (mppsol_cpi, payment settlement, intent execution)
spec/security.md	Threat model, validator rotation, replay protection, prover liveness
spec/tempo-chainspec.md	Reverse-engineered Moderato testnet observations: consensus context, 0x76 tx envelope, native stablecoin precompiles, open questions

Components

This repository is a monorepo. Each top-level folder is one component of zkTempo.sol.

Folder	Purpose	Status
spec/	Protocol specifications.	Draft
light-client/	Rust crate: Simplex BFT finality verification. no_std.	Scaffold
prover/	Rust host crate (API pinned) + SP1 guest crate at prover/program/ (compiles via cargo prove build, stub body via unimplemented!()).	Scaffold
solana/	Anchor verifier program (nested workspace).	Scaffold

License

Apache-2.0 (with patent grant). See LICENSE.

Maintainer

psyto.