SDK overview

The SDK is the client half of shh. It builds the exact witness inputs the circuits expect, manages notes and the Merkle tree, and (in Node) generates Groth16 proofs formatted for the Solidity verifiers.

#Two entry points

#What the main entry exports

// from "@shh/sdk"
export * from "./constants";   // FIELD_SIZE, LEVELS, ZERO_VALUE
export * from "./poseidon";    // poseidon([...])
export * from "./random";      // randomField()
export * from "./merkleTree";  // MerkleTree
export * from "./proof";       // formatProof()
export * from "./pool";        // PoolNote, buildPoolWithdrawInput
export * from "./utxo";        // Keypair, Utxo, buildTransactionInput, hashExtData

#Foundations

poseidon(inputs)

Promise-returning Poseidon hash over field elements — the one hash used everywhere.

randomField()

Cryptographically secure random F_p (Web Crypto getRandomValues, reduced into the field).

FIELD_SIZE / LEVELS / ZERO_VALUE

The constants from the cryptographic core.

#A typical client flow

1. 1
   Reconstruct the treeFetch leaves from the backend and build a local MerkleTree.
2. 2
   Build the witnessCall buildPoolWithdrawInput or buildTransactionInput with your note(s).
3. 3
   ProveRun Groth16 — @shh/sdk/node in Node, or a snarkjs Web Worker in the browser.
4. 4
   SubmitSend the formatted proof to the contract directly, or to the relayer for a gasless withdrawal.

Continue with the model that matches your profile: Privacy Pool notes or Shielded UTXO.