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Self-Custody Use Case (BTC-like)

This guide illustrates the creation of secrets, address synchronization, balance retrieval, and transaction sending from a client wallet application within Self-Custody using Spatium Signer Service.

Initialization

To interact with Spatium Signer Client, you need to provide the following data:

import { uuid, randomBytes, MemoryStorageDriver, SpatiumCrypto } from '@spatium/sdk';
import { AuthorizationSession, ServiceStorage, SignerClient } from '@spatium/signer-client';

export const createSignerClient = () => {
  const auth = new AuthorizationSession('https://cloud.spatium.net/authorization/v1', uuid(randomBytes), ['read', 'secret']);
  const storage = new ServiceStorage('https://cloud.spatium.net/storage/v1', auth);

  const cache = new MemoryStorageDriver()
  const crypto = new SpatiumCrypto(cache, storage)

  return new SignerClient('https://cloud.spatium.net/signer/v1', auth, crypto, 10 * 1000);
};

import SpatiumSDKSwift
import SignerClientSwift

func createSignerClient() -> SignerClient {
    let auth = AuthorizationSession(
        url: "https://cloud.spatium.net/authorization/v1",
        tokenId: UUID().uuidString,
        permissions: ["read", "secret"]
    )

    let clientCache = MemoryStorageDriver()
    let clientStorage = MemoryStorageDriver()

    let clientCrypto = SpatiumCrypto(cache: clientCache, storage: clientStorage)

    let clientProtocol = SignerClient(
        url: "https://cloud.spatium.net/signer/v1",
        auth: auth,
        crypto: clientCrypto,
        timeout: 10 * 1000
    )

    return clientProtocol
}

Important! In the TypeScript example, ServiceStorage is used as storage, which stores both secrets at Spatium. Using this format implies that the wallet is custodial. It's not recommended for production use.

Secret Generation

To use a distributed wallet, you need to generate a permanent pair of client and server secrets and ensure their secure storage. On the Spatium Signer Service side, secret management is automated, while on the client side, the developer must implement a stableStorageDriver on their own. In both cases, the secret is bound to its identifier (secretId) and is accessible through it after creation. A user can have any number of secrets, but to ensure their security and recoverability, it is recommended to use one secret per user.

To backup secrets in case of StorageDriver content loss, it is recommended to use export and import features.

export const ensureSecret = async (signerClient: SignerClient, secretId: string) => {
  if (await signerClient.crypto.checkSecret(secretId)) {
    return;
  }

  try {
    // Wait for the actual connection to be established
    await signerClient.connect(10 * 1000);

    await signerClient.generateDistributedSecret(secretId);
  } finally {
    await signerClient.disconnect();
  }
};

func ensureSecret(signerClient: SignerClient, secretId: String) async throws {
    if (await signerClient.crypto.checkSecret(secretId: secretId)) {
        return;
    }

    // Wait for the actual connection to be established
    try await signerClient.connect(timeout: 10 * 1000);
    defer {
        signerClient.disconnect()
    }
    try await signerClient.generateDistributedSecret(secretId: secretId);
};

Important! At this stage of SDK development, it is recommended to use a similar approach when interacting with the service, i.e., connecting immediately before interaction and disconnecting afterwards. This will help to avoid common network errors until they are fully resolved.

Synchronizing Currency Addresses

A currency address is required to receive assets and request balance information, so it is recommended to synchronize it immediately when creating a wallet.

To reduce synchronization time and improve user experience, it is recommended to use a single public key (sync parameters) for all currencies within the same cryptographic system. To do so, first synchronize one public key for the corresponding cryptographic system and then generate the desired currencies' addresses with it.

Each new synchronization procedure is bound to a unique identifier, and its results are recorded in the provided StorageDriver, which allows (with a saved syncSessionId) to synchronize the key once and then use the results permanently. However, loss of the synchronization data does not have long-term consequences, as it is possible to perform synchronization again and obtain the same public key and addresses.

The following data is required for the synchronization procedure:

  • secretId - identifier of the secret, serving as the entropy for this wallet. Secrets must have already been generated by the time of synchronization;
  • syncSessionId - synchronization session identifier. In case of a match, the previous session with such identifier will be overwritten;
  • curve - the elliptic curve. For all currencies of this example it is secp256k1;
  • derivationCoin - HD key derivation parameter that directly affects the address generation result. Unique values lead to the generation of unique keys. It is recommended to use a fixed value for a specific cryptographic system and vary the key value using the next parameter;
  • derivationAccount - HD key derivation parameter that directly affects the address generation result. Unique values lead to the generation of unique keys.
import { syncDistributedEcdsaKey, getEcdsaPublicKey } from '@spatium/sdk';

export const ensureEcdsaPublicKey = async (signerClient: SignerClient, secretId: string, syncSessionId: string, derivationCoin: number, derivationAccount: number): Promise<string> => {
  const publicKey = await getEcdsaPublicKey(signerClient, secretId, syncSessionId).catch(() => null);
  if (publicKey) {
    return publicKey;
  }

  try {
    // Wait for the actual connection to be established
    await signerClient.connect(10 * 1000);

    const distributedEcdsaKey = await syncDistributedEcdsaKey(signerClient, secretId, syncSessionId, 'secp256k1', derivationCoin, derivationAccount);
    return distributedEcdsaKey
  } finally {
    await signerClient.disconnect();
  }
};

func ensureEcdsaPublicKey(signerClient: SignerClient, secretId: String, syncSessionId: String, derivationCoin: UInt32, derivationAccount: UInt32) async throws -> String {

    let publicKey = try await getEcdsaPublicKey(driver: signerClient, secretId: secretId, syncSessionId: syncSessionId) 

  if !publicKey.isEmpty {
    return publicKey
  }

  // Wait for the actual connection to be established
  try await signerClient.connect(timeout: 10 * 1000)

  let distributedEcdsaKey = try await syncDistributedEcdsaKey(
    driver: signerClient,
    secretId: secretId,
    syncSessionId: syncSessionId,
    curve: .secp256k1,
    derivationCoin: derivationCoin,
    derivationAccount: derivationAccount
  )

  return distributedEcdsaKey
}

To obtain an address in a specific blockchain from a public key, it is recommended to use Blockchain Connector Service.

import axios from 'axios';
import { randomBytes, uuid } from '@spatium/sdk';

type BtcLikeGetAddressRequest = {
  network?: 'livenet' | 'testnet';
  publicKey: string;
  type?: 'p2pkh' | 'p2wpkh';
  prefix?: boolean;
};
type BtcLikeGetAddressResponse = {
  requestId: string;
  data: { address: string };
};

export const btcLikeGetAddress = async (
  auth: AuthorizationSession,
  chain: BTCLikeChain,
  { network, publicKey, type, prefix }: BtcLikeGetAddressRequest,
): Promise<BtcLikeGetAddressResponse['data']> => {
  const token = await auth.getPermissionToken();

  const response = await axios.post(
    `https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/get-address/${chain}`,
    {
      publicKey,
      network,
      type,
      prefix,
    },
    {
      headers: {
        'request-id': uuid(randomBytes),
        'authorization': `Bearer ${token}`,
      },
    },
  ).then((result) => result.data);

  return response.data;
};

enum BTCLikeChain: String, Codable {
    case btc
    case ltc
    case bch
    case doge
}

struct BtcLikeGetAddressRequest: Codable {
    enum Network: String, Codable {
        case livenet
        case testnet
    }

    enum AddressType: String, Codable {
        case p2pkh
        case p2wpkh
    }

    let network: Network?
    let publicKey: String
    let type: AddressType
    let prefix: Bool?
}

struct BtcLikeGetAddressResponse: Decodable {
  let requestId: String
  let data: DataResponse
}

struct DataResponse: Decodable {
  let address: String
}

func btcLikeGetAddress(auth: AuthorizationSession, chain: BTCLikeChain, addressRequest: BtcLikeGetAddressRequest) async throws -> String? {
    guard let url = URL(string: "https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/get-address/\(chain)") else { throw CustomError.urlError }

    let token = try await auth.getPermissionToken()

    let headers: [String: String] = [
        "request-id": UUID().uuidString,
        "authorization": "Bearer \(token)"
    ]

    var request = URLRequest(url: url)
    request.httpMethod = "POST"

    headers.forEach { (key, value) in
        request.addValue(value, forHTTPHeaderField: key)
    }
    request.addValue("application/json", forHTTPHeaderField: "Content-Type")

    guard let body = try? JSONEncoder().encode(addressRequest) else {
        throw CustomError.configurationError
    }

    request.httpBody = body

    let (data,_) = try await URLSession.shared.data(for: request)
    guard let address = try? JSONDecoder().decode(BtcLikeGetAddressResponse.self, from: data) else {
        throw CustomError.codingError
    }

    return address.data.address
}

Important! In order to be able to restore all addresses with user funds in case of data loss in the StorageDriver, it is necessary to ensure backup of a client secret and an external storage of address generation parameters, specifically:

  • secretId - generation data, also needs to be stored along with the secret backup
  • curve - generation data
  • derivationCoin - generation data
  • derivationAccount - generation data

Retrieving Address Information

Having a synchronized address (or any other address), you can access the Address Info Service to retrieve detailed information about the address, including various assets' balances and transaction history.

import axios from 'axios';
import { randomBytes, uuid } from '@spatium/sdk';

type AddressInfo = {
  address: string;
  chain: string;
  balances: [
    {
      asset: { chain: string, kind: string },
      balance: { amount: string, decimals: number }
    }
  ];
  transactions: [];
}
type BtcLikeGetAddressInfoRequest = {
  network?: 'livenet' | 'testnet';
  address: string;
};
type BtcLikeGetAddressInfoResponse = {
  requestId: string;
  data: AddressInfo;
};

export const btcLikeGetAddressInfo = async (
  auth: AuthorizationSession,
  chain: BTCLikeChain,
  { network, address }: BtcLikeGetAddressInfoRequest,
): Promise<BtcLikeGetAddressInfoResponse['data']> => {
  const token = await auth.getPermissionToken();

  const result = await axios.get(
    `https://cloud.spatium.net/address-info-btc-like/v1/api/${chain}`,
    {
      params: { network, address },
      headers: {
        'request-id': uuid(randomBytes),
        'authorization': `Bearer ${token}`,
      },
    },
  ).then((result) => result.data);

  return result.data;
};

struct AddressInfo: Codable {
  let address: String
  let chain: String
  let balances: [Balance]
  // let transactions: [Transaction]
}

struct Balance: Codable {
  let asset: Asset
  let balance: BalanceAmount
}

struct Asset: Codable {
  let chain: String
  let kind: String
}

struct BalanceAmount: Codable {
  let amount: String
  let decimals: Int
}

//    struct Transaction {
//      // properties
//    }

struct BtcLikeGetAddressInfoRequest {
    enum Network: String, Codable {
        case livenet
        case testnet
    }
    let network: Network?
    let address: String
}

struct BtcLikeGetAddressInfoResponse: Codable {
  let requestId: String
  let data: AddressInfo
}

func btcLikeGetAddressInfo(auth: AuthorizationSession,
                           chain: BTCLikeChain,
                           addressInfoRequest: BtcLikeGetAddressInfoRequest) async throws -> AddressInfo {
    let token = try await auth.getPermissionToken()
    var url = URLComponents(string: "https://cloud.spatium.net/address-info-btc-like/v1/api/\(chain)")!
    let params = [
        "address": addressInfoRequest.address,
        "network": addressInfoRequest.network?.rawValue
    ]

    url.queryItems = params.map { (key, value) in
        URLQueryItem(name: key, value: value)
    }

    var request = URLRequest(url: url.url!)
    request.httpMethod = "GET"
    request.addValue(UUID().uuidString, forHTTPHeaderField: "request-id")
    request.addValue("Bearer \(token)", forHTTPHeaderField: "authorization")

    let (data, _) = try await URLSession.shared.data(for: request)

    let result = try JSONDecoder().decode(BtcLikeGetAddressInfoResponse.self, from: data)

    return result.data
}

Transaction Signing

Transaction signing includes several steps:

  • Gathering current data from a blockchain, such as UTXO or nonce.
  • Estimating a transaction fee.
  • Generating a transaction hash.
  • Signing a transaction hash.
  • Creating a signed transaction.
  • Sending the transaction to the blockchain.

Of all these stages, only the signing of the transaction hash is performed using the SDK, the rest is provided through the Blockchain Connector Service API.

UTXO Gathering

Bitcoin-like currencies require up-to-date Unspent Transaction Outputs (UTXO) for transaction formation.

import axios from 'axios';
import { randomBytes, uuid } from '@spatium/sdk';

type BtcLikeGetUTXORequest = {
  network?: 'livenet' | 'testnet';
  address: string;
};
type UTXO = {
  txid: string;
  vout: number;
  value: string;
};
type BtcLikeGetUTXOResponse = {
  requestId: string;
  data: { utxo: UTXO[] };
};

export const btcLikeGetUTXO = async (
  auth: AuthorizationSession,
  chain: BTCLikeChain,
  { network, address }: BtcLikeGetUTXORequest,
): Promise<BtcLikeGetUTXOResponse['data']> => {
  const token = await auth.getPermissionToken();

  const response = await axios.get(
    `https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/prepare-transaction/utxo-list/${chain}`,
    {
      params: { network, address },
      headers: {
        'request-id': uuid(randomBytes),
        'authorization': `Bearer ${token}`,
      },
    },
  ).then((result) => result.data);

  return response.data;
};

struct BtcLikeGetUTXORequest {
    enum Network: String, Codable {
        case livenet
        case testnet
    }
    let network: Network?
    let address: String
}

struct UTXO: Codable {
    let txid: String
    let vout: Int
    let value: String
}

struct UTXData: Codable {
    let utxo: [UTXO]
}

struct BtcLikeGetUTXOResponse: Codable {
  let requestId: String
  let data: UTXData
}

func btcLikeGetUTXO(auth: AuthorizationSession, chain: BTCLikeChain, request: BtcLikeGetUTXORequest) async throws -> [UTXO] {
    let token = try await auth.getPermissionToken()

    var url = URLComponents(string:"https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/prepare-transaction/utxo-list/\(chain)")!

    var params = [
        "address": request.address
    ]

    if let network = request.network {
        params["network"] = network.rawValue
    }

    url.queryItems = params.map { (key, value) in
        URLQueryItem(name: key, value: value)
    }

    let uuid = UUID().uuidString
    let headers = [
        "request-id": uuid,
        "authorization": "Bearer \(token)"
    ]

    var request = URLRequest(url: url.url!)
    request.httpMethod = "GET"

    headers.forEach { (key, value) in
        request.addValue(value, forHTTPHeaderField: key)
    }

    let (data, _) = try await URLSession.shared.data(for: request)
    let decodedResponse = try JSONDecoder().decode(BtcLikeGetUTXOResponse.self, from: data)

    return decodedResponse.data.utxo
}

Transaction Size Estimation

To estimate the transaction fee in Bitcoin-like blockchains, the transaction size in bytes is used, which requires knowledge of UTXO as well.

import axios from 'axios';
import { randomBytes, uuid } from '@spatium/sdk';

type BtcLikeGetTXSizeRequest = {
  network?: 'livenet' | 'testnet';
  publicKey: string;
  type?: 'p2pkh' | 'p2wpkh';
  utxo: { txid: string; vout: number; value: string }[];
  to: string;
  amount: string;
};
type BtcLikeGetTXSizeResponse = { 
  requestId: string;
  data: { size: number };
};

export const btcLikeGetTXSize = async (
  auth: AuthorizationSession,
  chain: BTCLikeChain,
  { network, publicKey, type, utxo, to, amount }: BtcLikeGetTXSizeRequest,
): Promise<BtcLikeGetTXSizeResponse['data']> => {
  const token = await auth.getPermissionToken();

  const response = await axios.post(
    `https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/prepare-transaction/size/${chain}`,
    {
      publicKey,
      network,
      type,
      utxo,
      to,
      amount,
    },
    {
      headers: {
        'request-id': uuid(randomBytes),
        'authorization': `Bearer ${token}`,
      },
    },
  ).then((result) => result.data);

  return response.data;
};

struct BtcLikeGetTXSizeRequest: Codable {
    enum Network: String, Codable {
        case livenet
        case testnet
    }
    enum AddressType: String, Codable {
        case p2pkh
        case p2wpkh
    }

    let network: Network?
    let publicKey: String
    let type: AddressType?
    let utxo: [UTXO]
    let to: String
    let amount: String
}

struct UTXO: Codable {
    let txid: String
    let vout: Int
    let value: String
}

struct BtcLikeGetTXSizeResponse: Codable {
    let requestId: String
    let data: SizeResponse
}

struct SizeResponse: Codable {
    let size: Int
}

func btcLikeGetTXSize(auth: AuthorizationSession, chain: BTCLikeChain, sizeRequest: BtcLikeGetTXSizeRequest) async throws -> SizeResponse {
    let token = try await auth.getPermissionToken()
    guard let url = URL(string: "https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/prepare-transaction/size/\(chain)")
                      else { throw CustomError.urlError}

    let headers = [
        "request-id": UUID().uuidString,
        "authorization": "Bearer \(token)",
        "Content-Type": "application/json"
    ]

    var request = URLRequest(url: url)
    request.httpMethod = "POST"

    headers.forEach { (key, value) in
        request.addValue(value, forHTTPHeaderField: key)
    }

    guard let body = try? JSONEncoder().encode(sizeRequest) else {
        throw CustomError.configurationError
    }

    request.httpBody = body

    let (data, _) = try await URLSession.shared.data(for: request)

    let result = try JSONDecoder().decode(BtcLikeGetTXSizeResponse.self, from: data)

    return result.data
}

Getting Information about an Average Network Commission

import axios from 'axios';
import { randomBytes, uuid } from '@spatium/sdk';

type BtcLikeGetBytePricesRequest = {
  network?: 'livenet' | 'testnet';
};
type BtcLikeGetBytePricesResponse = {
  data: {[key: string] : {
    date: number,
    feeInfo: {
      fast: string,
      normal: string,
      slow: string,
    }
  }}
}

export const btcLikeGetBytePrices = async (
  auth: AuthorizationSession,
  { network }: BtcLikeGetBytePricesRequest,
): Promise<BtcLikeGetBytePricesResponse['data']> => {

  const token = await auth.getPermissionToken();

  const response = await axios.get(
    `https://cloud.spatium.net/fee-info-btc-like/v1/static/fee-info-${network}.json`, {
      params: { network },
      headers: {
        'request-id': uuid(randomBytes),
        'authorization': `Bearer ${token}`,
      },
    },
  ).then((result) => result.data);

  return response;
};

enum Network: String, Codable {
    case livenet
    case testnet
}

struct BtcLikeGetBytePricesResponse: Codable {
    let data: [String: BtcLikeFeeInfo]
}

struct BtcLikeFeeInfo: Codable {
    let date: Date
    let feeInfo: BtcLikeFeeDetails
}

struct BtcLikeFeeDetails: Codable {
    let fast: String
    let normal: String
    let slow: String
}

func btcLikeGetBytePrices(auth: AuthorizationSession, network: Network) async throws -> [String: BtcLikeFeeInfo] {
    let token = try await auth.getPermissionToken()

    let url = URL(string: "https://cloud.spatium.net/fee-info-btc-like/v1/static/fee-info-\(network?.rawValue ?? "livenet").json")!

    var request = URLRequest(url: url)
    request.httpMethod = "GET"

    request.addValue(UUID().uuidString, forHTTPHeaderField: "request-id")
    request.addValue("Bearer \(token)", forHTTPHeaderField: "authorization")

    let (data, _) = try await URLSession.shared.data(for: request)

    let response = try JSONDecoder().decode([String: BtcLikeFeeInfo].self, from: data)

    return response
}

Calculating Transaction Fee

The final value of the optimal fee is determined by the transaction size and the average cost per byte. Additionally, you can manually input the total fee amount, disregarding both the size and estimation.

const fee = (Number(prices.normal) * size).toFixed();

let normalFee = Double(prices.feeInfo.normal)! 
let fee = (normalFee * Double(size)).rounded()

Transaction Hash

With all the preliminary data, it is possible to form a signing hash (in this case, a set of hashes).

import axios from 'axios';
import { randomBytes, uuid } from '@spatium/sdk';

type BtcLikeGetHashRequest = {
  network?: 'livenet' | 'testnet';
  publicKey: string;
  type?: 'p2pkh' | 'p2wpkh';
  utxo: { txid: string; vout: number; value: string }[];
  to: string;
  amount: string;
  fee: string;
};
type BtcLikeGetHashResponse = {
  requestId: string;
  data: {
    inputIndex: number;
    hash: string;
  }[];
};

export const btcLikeGetHash = async (
  auth: AuthorizationSession,
  chain: BTCLikeChain,
  { network, publicKey, type, utxo, to, amount, fee }: BtcLikeGetHashRequest,
): Promise<BtcLikeGetHashResponse['data']> => {
  const token = await auth.getPermissionToken();

  const response = await axios.post(
    `https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/transaction/get-hash/${chain}`,
    {
      network,
      publicKey,
      type,
      utxo,
      to,
      amount,
      fee,
    },
    {
      headers: {
        'request-id': uuid(randomBytes),
        'authorization': `Bearer ${token}`,
      },
    },
  ).then((result) => result.data);

  return response.data;
};

struct BtcLikeGetHashRequest: Codable {
    var network: Network?
    var publicKey: String
    var type: AddressType?
    var utxo: [UTXO]
    var to: String
    var amount: String
    var fee: String
}

struct UTXO: Codable {
    var txid: String
    var vout: Int
    var value: String
}

struct BtcLikeGetHashResponse: Codable {
    var requestId: String
    var data: DataHashes
}

struct DataHashes : Codable {
    let hashes : [HashData]?
}

struct HashData: Codable {
    var inputIndex: Int
    var hash: String
}

func btcLikeGetHash(auth: AuthorizationSession, chain: BTCLikeChain, request: BtcLikeGetHashRequest) async throws -> [HashData]? {

    let token = try await auth.getPermissionToken()

    let url = "https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/transaction/get-hash/\(chain)"
    var urlRequest = URLRequest(url: URL(string: url)!)
    urlRequest.httpMethod = "POST"
    urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
    urlRequest.addValue(UUID().uuidString, forHTTPHeaderField: "request-id")
    urlRequest.addValue("Bearer \(token)", forHTTPHeaderField: "authorization")

    guard let body = try? JSONEncoder().encode(request) else {
        throw CustomError.configurationError
    }
    urlRequest.httpBody = body

    let (data, _) = try await URLSession.shared.data(for: urlRequest)

    let response = try JSONDecoder().decode(BtcLikeGetHashResponse.self, from: data)

    return response.data.hashes
}

Getting signingToken

import { randomBytes, uuid } from '@spatium/sdk';

export const getSigningToken = async (message: string): Promise<string> => {

  const { data: { permissionToken: { permissionToken: signingToken } } } = await axios.post('https://cloud.spatium.netauthorization/v1/api/permission/issue-by-key', {
    tokenId: uuid(randomBytes),
    permissions: ['sign'],
    payload: message,
    merchantKey: 'your-merchant-key',
  }).then(({ data }) => data);

  return signingToken;
};

//    struct PermissionRefreshToken : Codable {
//        let permissionRefreshToken : String?
//        let issuer : String?
//        let expiresAt : Int?
//    }

struct PermissionToken : Codable {
    let permissionToken : String
    let issuer : String?
    let expiresAt : Int?
}

struct TokenModel : Codable {
    //        let permissionRefreshToken : PermissionRefreshToken?
    let permissionToken : PermissionToken
}

struct IssueKeyResponse : Codable {
    let requestId : String
    let data : TokenModel
}

func getSigningToken(message: String) async throws -> String {
    let tokenId = UUID().uuidString

    let url = URL(string: "https://cloud.spatium.net/authorization/v1/api/permission/issue-by-key")!
    var request = URLRequest(url: url)
    request.httpMethod = "POST"

    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    request.addValue(UUID().uuidString, forHTTPHeaderField: "request-id")

    let body: [String: Any] = [
        "tokenId": tokenId,
        "permissions": ["sign"],
        "payload": message,
        "merchantKey": Constants.merchantKey //"your-merchant-key"
    ]

    request.httpBody = try JSONSerialization.data(withJSONObject: body, options: [])

    let (data, _) = try await URLSession.shared.data(for: request)

    guard let tokenModel = try? JSONDecoder().decode(IssueKeyResponse.self, from: data) else {
        throw CustomError.codingError
    }

    return tokenModel.data.permissionToken.permissionToken
}

SMPC Hash Signature

import { randomBytes, uuid } from '@spatium/sdk';

export const signEcdsa = async (signerClient: SignerClient, secretId: string, syncSessionId: string, message: string, signingToken: string): Promise<EcdsaSignature> => {
  const signSessionId = uuid(randomBytes);

  try {
    // Wait for the actual connection to be established
    await signerClient.connect(10 * 1000);

    return await signerClient.signEcdsaMessage(secretId, syncSessionId, signSessionId, message, signingToken);
  } finally {
    await signerClient.disconnect();
  }
};

func signEcdsa(signerClient: SignerClient, secretId: String, syncSessionId: String, message: String, signingToken: String) async throws -> EcdsaSignature {

    let signSessionId = UUID().uuidString

    // Wait for the actual connection to be established
    try await signerClient.connect(timeout: 10 * 1000)

    defer {
        signerClient.disconnect()
    }

    do {
        let signature = try await signerClient.signEcdsaMessage(secretId: secretId,
                                                                syncSessionId: syncSessionId,
                                                                signSessionId: signSessionId,
                                                                message: message,
                                                                signatureToken: signingToken)
        return signature
    } catch {
        throw error
    }
}

Forming a Signed Transaction

A signature (in this case, a set of signatures) needs to be attached to a transaction, thereby obtaining data ready to be sent to the blockchain.

import axios from 'axios';
import { randomBytes, uuid } from '@spatium/sdk';

type BtcLikeAttachSignatureRequest = {
  network?: 'livenet' | 'testnet';
  publicKey: string;
  type?: 'p2pkh' | 'p2wpkh';
  utxo: { txid: string; vout: number; value: string }[];
  to: string;
  amount: string;
  fee: string;
  signatures: { inputIndex: number; signature: EcdsaSignature }[];
};
type BtcLikeAttachSignatureResponse = {
  requestId: string;
  data: { txdata: string };
};

export const btcLikeAttachSignature = async (
  auth: AuthorizationSession,
  chain: BTCLikeChain,
  { network, publicKey, type, utxo, to, amount, fee, signatures }: BtcLikeAttachSignatureRequest,
): Promise<BtcLikeAttachSignatureResponse['data']> => {
  const token = await auth.getPermissionToken();

  const response = await axios.post(
    `https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/transaction/attach-signature/${chain}`,
    {
      publicKey,
      network,
      type,
      utxo,
      to,
      amount,
      fee,
      signatures,
    },
    {
      headers: {
        'request-id': uuid(randomBytes),
        'authorization': `Bearer ${token}`,
      },
    },
  ).then((result) => result.data);

  return response.data;
};

struct BtcLikeAttachSignatureRequest: Encodable {
    let network: Network?
    let publicKey: String
    let type: AddressType?
    let utxo: [UTXO]
    let to: String
    let amount: String
    let fee: String
    let signatures: [Signature]
}

struct UTXO: Encodable {
    let txid: String
    let vout: Int
    let value: String
}

struct Signature: Encodable {
    let inputIndex: Int
    let signature: EcdsaSignature
}

struct BtcLikeAttachSignatureResponse: Decodable {
    let requestId: String
    let data: TransactionData
}

struct TransactionData: Decodable {
    let txdata: String
}

func btcLikeAttachSignature(auth: AuthorizationSession,
                            chain: BTCLikeChain,
                            request: BtcLikeAttachSignatureRequest) async throws -> TransactionData {

    let token = try await auth.getPermissionToken()

    var urlRequest = URLRequest(url: URL(string: "https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/transaction/attach-signature/\(chain)")!)
    urlRequest.httpMethod = "POST"
    urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
    urlRequest.setValue("Bearer \(token)", forHTTPHeaderField: "authorization")
    urlRequest.setValue(UUID().uuidString, forHTTPHeaderField: "request-id")

    guard let body = try? JSONEncoder().encode(request) else {
        throw CustomError.configurationError
    }
    urlRequest.httpBody = body

    let (data, _) = try await URLSession.shared.data(for: urlRequest)

    let response = try JSONDecoder().decode(BtcLikeAttachSignatureResponse.self, from: data)
    return response.data
}

Sending a Transaction to the Network

Blockchain Connector Service is also responsible for sending the transaction to a blockchain

import axios from 'axios';
import { randomBytes, uuid } from '@spatium/sdk';

type BtcLikeSendTXRequest = {
  network?: 'livenet' | 'testnet';
  txdata: string;
};
type BtcLikeSendTXResponse = {
  requestId: string;
  data: { txid: string };
};

export const btcLikeSendTX = async (
  auth: AuthorizationSession,
  chain: BTCLikeChain,
  { network, txdata }: BtcLikeSendTXRequest,
): Promise<BtcLikeSendTXResponse> => {
  const token = await auth.getPermissionToken();

  const response = await axios.post(
    `https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/transaction/send/${chain}`,
    {
      network,
      txdata,
    },
    {
      headers: {
        'request-id': uuid(randomBytes),
        'authorization': `Bearer ${token}`,
      },
    }
  ).then((result) => result.data);

  return response.data;
};

struct BtcLikeSendTXRequest: Encodable {
    let network: String?
    let txdata: String
}

struct BtcLikeSendTXResponse: Decodable {
    let requestId: String
    let data: TransactionIdData
}

struct TransactionIdData: Decodable {
    let txid: String
}

func btcLikeSendTX(auth: AuthorizationSession,
                   chain: BTCLikeChain,
                   request: BtcLikeSendTXRequest) async throws -> BtcLikeSendTXResponse {

    let token = try await auth.getPermissionToken()

    var urlRequest = URLRequest(url: URL(string: "https://cloud.spatium.net/blockchain-connector-btc-like/v1/api/transaction/send/\(chain)")!)
    urlRequest.httpMethod = "POST"
    urlRequest.addValue("application/json", forHTTPHeaderField: "Content-Type")
    urlRequest.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
    urlRequest.setValue(UUID().uuidString, forHTTPHeaderField: "request-id")

    let data = try JSONEncoder().encode(request)
    urlRequest.httpBody = data

    let (responseData, _) = try await URLSession.shared.data(for: urlRequest)
    print("btcLikeSendTX response json \(String(data: responseData, encoding: .utf8) ?? "NADA")")

    let response = try JSONDecoder().decode(BtcLikeSendTXResponse.self, from: responseData)
    return response
}

Complete Procedure

import { AuthorizationSession, SignerClient } from '@spatium/signer-client';
import { randomBytes, uuid } from '@spatium/sdk';

const auth = new AuthorizationSession('https://cloud.spatium.net/authorization/v1', uuid(randomBytes), ['read', 'secret']);

// get security tokens
const { data: { securityToken } } = await axios.post('https://cloud.spatium.net/authorization/v1/api/security-factor/credentials', {
    username: 'username', password: 'password',
  }, {
    headers: {
      'request-id': uuid(randomBytes),
    },
  }).then(({ data }) => data);

await auth.establish([securityToken]);

const btcLikeSignTransaction = async (auth: AuthorizationSession, signerClient: SignerClient, syncSessionId: string, 
  chain: BTCLikeChain, publicKey: string, to: string, amount: string) => {

  const { address } = await btcLikeGetAddress(auth, 'btc', { publicKey });

  const { utxo } = await btcLikeGetUTXO(auth, 'btc', { address });

  const { size } = await btcLikeGetTXSize(auth, 'btc', { publicKey, utxo, to, amount });

  const pricePerByte = await btcLikeGetBytePrices(auth, {});

  const fee = (Number(pricePerByte.btc?.feeInfo.normal) * size).toFixed();

  const { hashes } = await btcLikeGetHash(auth, 'btc', { publicKey, utxo, to, amount, fee });

  const signatures: { inputIndex: number; signature: EcdsaSignature }[] = [];


  for (const { inputIndex, hash } of hashes) {

    const signingToken = await getSigningToken(hash)
    const signature = await signEcdsa(signerClient, syncSessionId, hash, signingToken);

    signatures.push({ inputIndex, signature });
  }

  const txdata = await btcLikeAttachSignature(auth, 'btc', { publicKey, utxo, to, amount, fee, signatures });

  const txid = await btcLikeSendTX(auth, 'btc', { txdata });

  return txid;
}

struct SecurityTokenResponseData : Codable, Equatable {
    let securityToken: String
}

struct SecurityTokenResponse : Codable, Equatable {
    let requestId: String
    let data: SecurityTokenResponseData
}

let auth = AuthorizationSession(url: "https://cloud.spatium.net/authorization/v1", tokenId: UUID().uuidString, permissions: ["read", "secret"])

let url = URL(string: "https://cloud.spatium.net/authorization/v1/api/security-factor/credentials")!

var request = URLRequest(url: url)
request.httpMethod = "POST"
guard let body = try? JSONEncoder().encode(["username": "username", "password": "password"])  else {
    throw CustomError.configurationError
}
request.httpBody = body

request.addValue(UUID().uuidString, forHTTPHeaderField: "Content-Type")

let (data,_) = try await URLSession.shared.data(for: request)
// get security tokens
let securityToken = try JSONDecoder().decode(SecurityTokenResponse.self, from: data).data.securityToken

try await auth.establish([securityToken])

struct Signature : Codable {
    let inputIndex : Int?
    let signature : EcdsaSignature?
}

func btcLikeSignTransaction(auth: AuthorizationSession, secretId: String, signerClient: SignerClient, syncSessionId: String, chain: BTCLikeChain, publicKey: String, to: String, amount: String) async throws -> String {
    let address = try await btcLikeGetAddress(auth: auth, chain: chain, addressRequest: BtcLikeGetAddressRequest(network: .testnet, publicKey: publicKey, type: .p2wpkh, prefix: false))

    let utxo = try await btcLikeGetUTXO(auth: auth, chain: .btc, request: BtcLikeGetUTXORequest(network: .testnet, address: address ?? ""))

    let sizeResponse = try await btcLikeGetTXSize(auth: auth, chain: .btc, sizeRequest: BtcLikeGetTXSizeRequest2(network: .testnet, publicKey: publicKey, type: .p2wpkh, utxo: utxo, to: to, amount: amount))
    let size = sizeResponse.size

    let priceResponse = try await btcLikeGetBytePrices(auth: auth, request: BtcLikeGetBytePricesRequest(network: .testnet))

    let pricePerByte = priceResponse[BTCLikeChain.btc.rawValue]?.feeInfo.normal ?? "0"
    let fee = (Double(pricePerByte)! * Double(size)).rounded().description

    guard let hashes = try await btcLikeGetHash(auth: auth, chain: .btc, request: BtcLikeGetHashRequest(publicKey: publicKey, utxo: utxo, to: to, amount: amount, fee: fee)) else {
        throw CustomError.codingError
    }

    var signatures = [Signature]()

    for hash in hashes {
        let inputIndex = hash.inputIndex
        let hash = hash.hash

        let signingToken = try await getSigningToken(message: hash)

        let signature = try await signEcdsa(signerClient: signerClient, secretId: secretId, syncSessionId: syncSessionId, message: hash, signingToken: signingToken)

        signatures.append(Signature(inputIndex: inputIndex, signature: signature))
    }

    let txdata = try await btcLikeAttachSignature(auth: auth,
                                                  chain: .btc,
                                                  request: BtcLikeAttachSignatureRequest(network: .testnet,
                                                                                         publicKey: publicKey,
                                                                                         type: .p2wpkh,
                                                                                         utxo: utxo,
                                                                                         to: to,
                                                                                         amount: amount,
                                                                                         fee: fee,
                                                                                         signatures: signatures
                                                                                        )
    )

    let txid = try await btcLikeSendTX(auth: auth, chain: .btc, request: BtcLikeSendTXRequest(network: .testnet, txdata: txdata.txdata))

    return txid.data.txid
}