TypeScript PoD SDK (CotiPodCrypto, PodContract)

The npm package @coti/pod-sdk ships TypeScript helpers for encrypting and decrypting PoD payloads and for encoding, fee estimation, and sending calls against your host-chain contract through coti-pod-crypto.ts and pod-method-call.ts.

Use these helpers from a wallet script, backend service, or dApp frontend once you have a Signer (or Provider for read-only helpers) and your contract ABI.

Encrypt and decrypt data (CotiPodCrypto)

CotiPodCrypto.encrypt POSTs to the PoD encryption service:

• "testnet" and "mainnet" resolve to SDK defaults.

• You can also pass a full encryption service URL.

• DataType distinguishes plaintext types (Uint64, String, etc.) from it* types that become ciphertext tuples on chain.

CotiPodCrypto.decrypt uses the user's account AES key and @coti-io/coti-sdk-typescript under the hood.

import { CotiPodCrypto, DataType } from "@coti/pod-sdk";

// Encrypt plaintext for Solidity itUint256 parameters
const enc = await CotiPodCrypto.encrypt("42", "testnet", DataType.itUint256);

// Decrypt scalar ciphertext read from contract storage
const plain = CotiPodCrypto.decrypt("0x...", accountAesKeyFromOnboarding, DataType.Uint64);

Gas estimation and method calls (PodContract)

PodContract wraps ethers.Contract with PoD-aware helpers:

• estimateFee for Inbox two-way fee calculation.

• encryptAndCallMethod to encrypt it* plaintext args and send the tx.

• callMethod to send pre-encrypted JSON ciphertext values.

• extractRequestIds(txHash) to parse Inbox MessageSent logs and recover request IDs for async tracking.

import {
  PodContract,
  DataType,
  type PodFeeEstimationConfig,
  type PodMethodArgument,
} from "@coti/pod-sdk";
import { ethers } from "ethers";

const pod = new PodContract(contractAddress, abi, signer, {
  encryptionNetwork: "testnet",
});

const args: PodMethodArgument[] = [
  { type: DataType.itUint256, value: "10", isCallBackFee: false },
  { type: DataType.itUint256, value: "20", isCallBackFee: false },
  { type: DataType.Uint256, value: "0", isCallBackFee: true }, // auto-replaced with callback fee
];

const feeCfg: PodFeeEstimationConfig = {
  forwardGasLimit: 400_000n,
  gasPrice: (await signer.provider!.getFeeData()).gasPrice ?? 0n,
  callBackGasLimit: 250_000n,
  callBackDataSize: 512n,
};

const fee = await pod.estimateFee("add", args, feeCfg);
// fee.totalFee, fee.remoteFee, fee.callBackFee

const txResponse = await pod.encryptAndCallMethod("add", args, feeCfg);
const receipt = await (txResponse as ethers.ContractTransactionResponse).wait();

const requestIds = receipt?.hash ? await pod.extractRequestIds(receipt.hash) : [];

Important fee config rules

• forwardGasLimit and gasPrice are required.

• callBackGasLimit and callBackDataSize must be provided together (or both omitted).

• forwardDataSize is optional; SDK can estimate from argument string sizes.

Choosing encryptAndCallMethod vs callMethod

• Use encryptAndCallMethod when your app currently has plaintext user input.

• Use callMethod when the app already has ciphertext JSON from a prior CotiPodCrypto.encrypt step and you want to submit it directly.

See also

• Tutorial: private Adder on Sepolia — full walkthrough including PodContract and extractRequestIds.

• Tutorial: custom privacy logic with PoD — custom COTI-side pattern.

• TypeScript integration (SDK docs)

• PoD SDK docs index