Deep dive into API concepts

Deep dive into API concepts

This page provides information on how to generate the following API headers and params:

Header / Param	Used in:
IMX-Timestamp IMX-Signature	createCollection updateCollection addMetadataSchemaToCollection updateMetadataSchemaByName createProject
x-imx-eth-signature	Get a list of metadata refreshes Requesting a metadata refresh Get metadata refresh results Get metadata refresh errors createOrder cancelOrder createTransferV1 createTransfer createWithdrawal createTrade createExchangeTransfer
stark_signature	createOrder cancelOrder createTransferV1 createTransfer createWithdrawal createTrade createExchangeTransfer
auth_signature	mintTokens

UPGRADE YOUR SDK TO AVOID GENERATING THESE HEADERS

If you are using the Core SDK or the JS SDK, you will generally not need to provide these headers as long as you upgrade to the following versions:

• Core SDK: >= 1.0.0-beta.2

• JS SDK: >= 1.17

IMX-Timestamp (string)​

The IMX-Timestamp can be generated by this example Javascript function:

Javascript

const timestamp = Math.floor(Date.now() / 1000).toString();

x-imx-eth-address (string)​

This is the public Ethereum address of the user executing the transaction.

IMX-Signature (string), x-imx-eth-signature (string), auth_signature (string)​

💡STEPS:

• Get Ethereum signer

• Get message to be signed

• Serialize the signature

1. Get Ethereum signer​

Signers are abstractions of user accounts that can be used to sign transactions. A user's private key is required to generate them. Read more here.

In order to generate the IMX-Signature and x-imx-eth-signature headers, we need an Ethereum signer for the user.

See here on how to generate these signers.

2. Get message​

Different messages are required by the different attributes:

Param	Message
IMX-Signature	IMX-Timestamp
x-imx-eth-signature	The message to be signed depends on each transaction. Typically, it contains information about the transaction that requires the user signature. The messages required for the following endpoints are: Get a list of metadata refreshes - expects a message of IMX timestamp Requesting a metadata refresh - expects a message of IMX timestamp Get metadata refresh results - expects a message of IMX timestamp Get metadata refresh errors - expects a message of IMX timestamp createOrder - expects a message of getSignableOrder cancelOrder - expects a message of getSignableOrder createTransferV1 - expects a message of getSignableTransfer createTransfer - expects a message of getSignableTransfer createWithdrawal - expects a message of getSignableWithdrawal createTrade - expects a message of getSignableTrade createExchangeTransfer - expects a message of getExchangeSignableTransfer
auth_signature	See below

How to get the message for the auth_signature?​

The auth_signature param is used in the mintTokens request.

1. Put together an object like the following Javascript example:

Javascript

const object = {
  contract_address: "string",
  royalties: [ // Optional
    {
      recipient: "string",
      percentage: "string",
    },
  ]
  users: [
    {
      ether_key: "string",
      tokens: [
        {
          id: "string",
          blueprint: "string",
          royalties: [ // Optional
            {
              recipient: "string",
              percentage: "string",
            },
          ]
        }
      ]
    }
  ],
};

1. Create a hash of that object that becomes the message to be signed to get the auth_signature:

Javascript

import { keccak256 } from '@ethersproject/keccak256';
import { toUtf8Bytes } from '@ethersproject/strings';

const message = keccak256(toUtf8Bytes(JSON.stringify(object)));

3. Serialize the signature​

Implement a function using the signer and message obtained in the previous steps like the following Typescript example:

Typescript

export async function signRaw(
  message: string,
  signer: Signer
): Promise<string> {
  const signature = deserializeSignature(await signer.signMessage(message));
  return serializeEthSignature(signature);
}

Where deserializeSignature() looks like:

Typescript

import BN from 'bn.js'; // https://www.npmjs.com/package/bn.js
import * as encUtils from 'enc-utils'; // https://www.npmjs.com/package/enc-utils

type SignatureOptions = {
  r: BN;
  s: BN;
  recoveryParam: number | null | undefined;
};

function importRecoveryParam(v: string): number | undefined {
  return v.trim()
    ? new BN(v, 16).cmp(new BN(27)) !== -1
      ? new BN(v, 16).sub(new BN(27)).toNumber()
      : new BN(v, 16).toNumber()
    : undefined;
}

function deserializeSignature(sig: string, size = 64): SignatureOptions {
  sig = encUtils.removeHexPrefix(sig);
  return {
    r: new BN(sig.substring(0, size), 'hex'),
    s: new BN(sig.substring(size, size * 2), 'hex'),
    recoveryParam: importRecoveryParam(sig.substring(size * 2, size * 2 + 2)),
  };
}

and serializeEthSignature() looks like:

Typescript

function serializeEthSignature(sig: SignatureOptions): string {
  // This is because golang appends a recovery param
  // https://github.com/ethers-io/ethers.js/issues/823
  return encUtils.addHexPrefix(
    encUtils.padLeft(sig.r.toString(16), 64) +
      encUtils.padLeft(sig.s.toString(16), 64) +
      encUtils.padLeft(sig.recoveryParam?.toString(16) || '', 2)
  );
}

stark_signature (string)​

The stark_signature is required in the request body params of certain endpoints. It is obtained by using a Stark signer to sign the payload_hash produced in the response of the following corresponding endpoints:

Action	Endpoint(s) requiring stark_signature	Endpoint(s) providing payload_hash to be signed
Create orders	createOrder	getSignableOrderV1 getSignableOrder
Cancel orders	cancelOrder	getSignableCancelOrder
Create transfers	createTransfer createTransferV1	getSignableTransfer getSignableTransferV1
Create withdrawals	createWithdrawal	getSignableWithdrawal
Create trades	createTrade	getSignableTrade
Create exchange transfers	createExchangeTransfer	getExchangeSignableTransfer

💡STEPS:

• Get message to be signed

• Generate StarkSigner and sign the message

1. Get message to be signed​

Call the corresponding endpoint to the one requiring the stark_signature that gets the payload_hash to be signed (ie. the endpoint that provides the payload_hash for the createWithdrawal endpoint is the getSignableWithdrawal endpoint).

2. Generate Stark signer and sign the message​

Use the Core SDK to generate the Stark signers. See instructions here.

Use the Stark signer to sign the payload_hash in Step 1:

• Typescript Core SDK

• Kotlin (JVM) Core SDK

• Swift Core SDK

• Golang Core SDK

const starkSignature = await starkSigner.signMessage(payloadHash);