> ## Documentation Index
> Fetch the complete documentation index at: https://docs.molpha.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Verifier Overview

> One signed payload, three VM families. Identical verification pipeline everywhere.

Every Molpha verifier runs the **same** [verification pipeline](/protocol/cryptography#the-verification-pipeline) over the same domain-separated hashes: derive the selection set from `(feedId, registryVersion, canonicalTimestamp)`, reconstruct the coalition key as the plain EC sum of the actual signers, and check one Schnorr signature over the canonical message. No `chainId` is in the message — that is what makes a single signature valid on every chain.

## The three implementations

|                     | Solana                                                                              | EVM                                               | Starknet                                            |
| ------------------- | ----------------------------------------------------------------------------------- | ------------------------------------------------- | --------------------------------------------------- |
| Role                | Canonical settlement + Rust verifier crate                                          | Stateless verifier                                | Stateless verifier                                  |
| Entrypoint          | `submit_data_update` writes the `Feed`; `molpha-verifier` verifies directly in Rust | `verify(dataUpdate, schnorrData) → bool` (`view`) | `verify(data_update, schnorr_data) → bool`          |
| Node-key storage    | `Node` PDAs (`molpha_node`)                                                         | SSTORE2 snapshot per version                      | per-`(version, index)` coordinate maps              |
| Schnorr final check | `molpha-verifier` uses the EVM-compatible Schnorr→ECDSA recovery path               | `ecrecover` trick (recovers `s·G − e·P`)          | native secp256k1 syscalls, computes `s·G + (Q−e)·P` |

The Starknet contract is a bit-for-bit port of the EVM pipeline, proven by parity tests that verify **unmodified EVM-produced signatures** on Cairo.

## What every verifier enforces

1. The `registryVersion` exists and has nodes.
2. Structural guards: non-zero `signaturesRequired`, `signersBitmap`, `signature`, `commitment`.
3. `popcount(signersBitmap) >= signaturesRequired`.
4. Signers ⊆ the deterministically derived selection set (`groupSize = min(signaturesRequired + redundancyBuffer, nodeCount)`).
5. The aggregate Schnorr signature over the canonical message.

## What no verifier enforces

Freshness, replay protection, and value bounds. A valid payload verifies forever (historical registry versions are intentionally kept verifiable). These policies belong to the consumer — see the integration checklists in each chain guide.