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Crypto SDK Guide

This guide will show you how Yellow Submarine allows users to convert an asset to a private asset and transfer it to a brand new wallet address by Findora Triple Masking.

It conducts two ZKP operations:

  • transfer asset to anonymous wallet from wallet A. (bar to abar)
  • transfer asset to wallet B from anonymous wallet. (abar to bar)

The combination of these two operations is the key to removing the trace.

Installing the Findora SDK​

To install the Findora SDK we only need to run one single command:

yarn add @findora-network/findora-sdk.js

1. Setup the Findora SDK​

  // Top-level await
const findoraSdk = await import('@findora-network/findora-sdk.js');
const findoraWasm = await findoraSdk.getWebLedger();

const { Network: NetworkApi, Transaction: TransactionApi } = findoraSdk.Api;

2. Create two Findora Wallet​

  // create a Findora Wallet, this wallet will be the source wallet
const keypairA = findoraWasm.new_keypair();
const walletA = {
keypair: keypairA,
keyStore: findoraWasm.keypair_to_str(keypairA),
privateKey: findoraWasm.get_priv_key_str(keypairA).replace(/\"/g, ''),
publickey: findoraWasm.get_pub_key_str(keypairA).replace(/\"/g, ''),
address: findoraWasm.public_key_to_bech32(findoraWasm.get_pk_from_keypair(keypairA)),
};

// create another Findora Wallet, this wallet will be the destination wallet
const keypairB = findoraWasm.new_keypair();
const walletB = {
keypair: keypairB,
keyStore: findoraWasm.keypair_to_str(keypairB),
privateKey: findoraWasm.get_priv_key_str(keypairB).replace(/\"/g, ''),
publickey: findoraWasm.get_pub_key_str(keypairB).replace(/\"/g, ''),
address: findoraWasm.public_key_to_bech32(findoraWasm.get_pk_from_keypair(keypairB)),
};

3. Create a Findora Anonymous Wallet​

  // create a Findora Anonymous Wallet
const anonKeys = findoraWasm.gen_anon_keys();
const anonWallet = {
axfrPublicKey: anonKeys.axfr_public_key,
axfrSecretKey: anonKeys.axfr_secret_key,
decKey: anonKeys.dec_key,
encKey: anonKeys.enc_key,
};

// release the anonymous keys instance
anonKeys.free();

4. Bar to Abar​

  // create an instance of the transaction builder
const transactionBuilder = await TransactionApi.getTransactionBuilder();

// get the informance of the UTXO by specific sid
const { response: [sid] } = await NetworkApi.getOwnedSids(walletA.address);
const { response: utxo } = await NetworkApi.getUtxo(sid);
const { response: ownerMemoData } = await NetworkApi.getOwnerMemo(sid);

const ownerMemo = ownerMemoData ? findoraWasm.OwnerMemo.from_json(ownerMemoData) : null;
const assetRecord = findoraWasm.ClientAssetRecord.from_json(utxo);

// the destination anonymous wallet
const axfrPublicKey = findoraWasm.axfr_pubkey_from_string(anonWallet.axfrPublicKey);
const encKey = findoraWasm.x_pubkey_from_string(anonWallet.encKey);

const keypair = findoraWasm.keypair_from_str(walletA.keyStore as string);

// add_operation_bar_to_abar will return a instance of the transactionBuilder, which would be used to submit the generated tx to the network
transactionBuilder = transactionBuilder.add_operation_bar_to_abar(
keypair,
axfrPublicKey,
BigInt(sid),
assetRecord,
ownerMemo?.clone(),
encKey,
);

// The only way to get access to the funds from the `abar` is to ensure that commitment is saved
// after the operation is completed and transaction is broadcasted.
// `commitments` MUST be saved in order to get access to the funds later.
const commitments = transactionBuilder?.get_commitments();

// Finally, broadcast this transaction to the network
await TransactionApi.submitTransaction(transactionBuilder.transaction());

5. Abar to Bar​

  // create an instance of the transaction builder
const transactionBuilder = await TransactionApi.getTransactionBuilder();

// the destination wallet
const receiverXfrPublicKey = findoraWasm.public_key_from_base64(walletB.publickey);

// the source anonymous wallet
const aXfrKeyPairSender = findoraWasm.axfr_keypair_from_string(anonWallet.axfrSecretKey);
const secretDecKeySender = findoraWasm.x_secretkey_from_string(anonWallet.decKey);

// we need to provide a commitment string which we would `transfer` to the destination wallet
const commitment = 'YOUR_COMMITMENT';

// `Abar to Bar` operation would require instances of abar, which will be created (restored)
// using the commitment strings
const { response: ownedAbarsResponse } = await NetworkApi.getOwnedAbars(commitment);
const [atxoSid, _ownedAbar] = ownedAbarsResponse;
// instances of abar
const ownedAbar = findoraWasm.abar_from_json(_ownedAbar);

// get the informance of the abar
const { response: abarOwnerMemoData } = await NetworkApi.getAbarOwnerMemo(atxoSid);
const { response: mtLeafInfoData } = await NetworkApi.getMTLeafInfo(atxoSid);
const abarOwnerMemo = findoraWasm.OwnerMemo.from_json(abarOwnerMemoData);
const mTLeafInfo = findoraWasm.MTLeafInfo.from_json(mtLeafInfoData);

// add_operation_abar_to_bar will return a instance of the transactionBuilder, which would be used to submit the generated tx to the network
transactionBuilder = transactionBuilder.add_operation_abar_to_bar(
ownedAbar,
abarOwnerMemo,
mTLeafInfo,
aXfrKeyPairSender,
secretDecKeySender,
receiverXfrPublicKey,
false,
false,
);

// Finally, broadcast this transaction to the network
await TransactionApi.submitTransaction(transactionBuilder.transaction());
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