zcash_shield

Instructions

Implementation Reference

• src/tools/shield.ts:4-55 (handler)

  The full implementation of the zcash_shield tool handler. It registers a server tool named 'zcash_shield' that accepts wallet_id, encryption_seed, shielded_address, amount_zatoshis, memo, and sui_private_key parameters. The handler computes the ZEC amount, returns a detailed flow description (UTXO listing, transaction building, sighash computation, Ika 2PC-MPC signing, broadcasting, and attestation), and returns the result as JSON. Error handling is included.

  export function registerShieldTool(server: McpServer) {
    server.tool(
      "zcash_shield",
      "Move ZEC from transparent (MPC custody) to shielded Orchard pool (local custody). " +
        "The transparent side is signed via Ika MPC. The shielded side uses the local Orchard wallet. " +
        "Every custody transition is attested to ZAP1.",
      {
        wallet_id: z.string().describe("dWallet object ID (transparent side)"),
        encryption_seed: z.string().describe("Hex encryption seed from wallet creation"),
        shielded_address: z.string().describe("Zcash unified address (u1...) for the Orchard pool"),
        amount_zatoshis: z.number().int().positive().describe("Amount in zatoshis to shield"),
        memo: z.string().max(512).optional().describe("Optional memo for the shielding transaction"),
        sui_private_key: z.string().describe("Sui private key for the MPC sign transaction"),
      },
      async ({ wallet_id, shielded_address, amount_zatoshis, memo }) => {
        try {
          const zec = amount_zatoshis / 1e8;
  
          const result = {
            status: "shield_flow",
            description: `Shield ${zec} ZEC from MPC custody to Orchard pool`,
            flow: [
              "1. List UTXOs on the t-addr (Zebra: z_listunspent)",
              "2. Build transparent TX: t-addr -> shielded_address",
              "3. Compute sighash (DoubleSHA256)",
              "4. Sign via Ika 2PC-MPC (secp256k1/ECDSA)",
              "5. Attach signature to TX",
              "6. Broadcast via Zebra (sendrawtransaction)",
              "7. Attest custody transition to ZAP1 (AGENT_ACTION)",
            ],
            custody_transition: {
              from: "MPC (split-key, neither party holds full key)",
              to: "Local Orchard wallet (RedPallas, full privacy)",
            },
            wallet_id,
            shielded_address,
            amount_zatoshis,
            memo: memo || null,
            note: "After shielding, ZEC is in the Orchard pool with full Zcash privacy. " +
              "The MPC wallet still exists for receiving new deposits.",
          };
  
          return {
            content: [{ type: "text" as const, text: JSON.stringify(result, null, 2) }],
          };
        } catch (err) {
          const msg = err instanceof Error ? err.message : String(err);
          return { content: [{ type: "text" as const, text: `Error: ${msg}` }], isError: true };
        }
      }
    );
  }

• src/index.ts:50-50 (registration)

  Registration of the shield tool in the main server entry point. registerShieldTool(server) is called to register zcash_shield on the MCP server.

  registerShieldTool(server);