@shakesco/bitcoin_base

Flutter/Dart SDK - This guide uses our Dart package for mobile and Flutter applications. For JavaScript/Node.js, see the JavaScript SDK.

Built With

Special thanks to Cake Wallet for their excellent Bitcoin base library.

Installation

Add to your pubspec.yaml:

dependencies:
  bitcoin_base:
    git:
      url: https://github.com/shakesco/bitcoin_base
      ref: cake-update-v5

Import the package:

import 'package:bitcoin_base/bitcoin_base.dart' as bitcoin_base;

Integration Workflow

Generate silent payment address

Create a reusable address for receiving payments

Create taproot destination

Generate unique address for each payment

Scan blockchain for funds

Detect incoming transactions

Spend received funds

Derive private keys and transfer Bitcoin

Step 1: Generate Silent Payment Address

From Private Keys
From Mnemonic (Wallets)

Best for: Apps where users control their own keys

void main() {
  final b_scan = ""; // Scan private key
  final b_spend = ""; // Spend private key

  final paymentOwner = bitcoin_base.SilentPaymentOwner.fromPrivateKeys(
    network: bitcoin_base.BitcoinNetwork.testnet,
    version: 0,
    b_scan: bitcoin_base.ECPrivate.fromHex(b_scan),
    b_spend: bitcoin_base.ECPrivate.fromHex(b_spend)
  );

  print(paymentOwner.toAddress());
}

Derive from signatures: Have users sign a message, then use the ECDSA signature components:

r → b_scan
s → b_spend

This ensures cryptographically secure randomness.

If not using signature derivation, ensure your random number generator is cryptographically secure.

Best for: Wallet applications managing user funds

void main() {
  final mnemonic = ""; // 12, 15, or 24 word phrase

  final paymentOwner = bitcoin_base.SilentPaymentOwner.fromMnemonic(mnemonic);
  print(paymentOwner.toAddress());
}

Alternative: From HD key

void main() {
  final paymentOwner = bitcoin_base.SilentPaymentOwner.fromHd();
  print(paymentOwner.toAddress());
}

Step 2: Create Taproot Destination

Generate a one-time taproot address for the payment:

void main() {
  // Parse recipient's silent payment address
  final B_scan = bitcoin_base.SilentPaymentAddress
      .fromAddress(paymentOwner.toAddress()).B_scan;
  final B_spend = bitcoin_base.SilentPaymentAddress
      .fromAddress(paymentOwner.toAddress()).B_spend;

  // Your UTXO details
  final tx_hash = "";
  final tx_id_output_index = 0;
  final sender_privateKey = "";
  final amount = 1000; // Satoshis

  // Build the destination
  final payto = bitcoin_base.SilentPaymentBuilder(
    vinOutpoints: [
      bitcoin_base.Outpoint(
        txid: tx_hash,
        index: tx_id_output_index
      )
    ]
  ).createOutputs(
    [
      bitcoin_base.ECPrivateInfo(
        bitcoin_base.ECPrivate.fromHex(sender_privateKey),
        false // Set true if UTXO is from taproot
      )
    ],
    [
      bitcoin_base.SilentPaymentDestination(
        amount: amount,
        network: bitcoin_base.BitcoinNetwork.testnet,
        version: 0,
        scanPubkey: B_scan,
        spendPubkey: B_spend
      )
    ]
  );

  // Get the taproot address
  final destinationAddress = payto.values.first.first.address
      .toAddress(bitcoin_base.BitcoinNetwork.testnet);
  print("Send $amount sats to: $destinationAddress");
}

Required inputs:

UTXO transaction hash and output index
UTXO private key
Amount in satoshis (1 BTC = 100,000,000 sats)
Recipient’s scan and spend public keys

Step 3: Scan for Incoming Funds

Scanning overhead: This is the main limitation of silent payments - you must scan the blockchain to detect incoming transactions.

Check if a transaction belongs to you:

void main() {
  final tx_hash = "";
  final tx_id_output_index = 0;
  final senders_pubKey = "";
  final amount = 1000;
  final Script = "";

  Map<String, bitcoin_base.SilentPaymentScanningOutput> output =
      bitcoin_base.SilentPaymentBuilder(
    vinOutpoints: [
      bitcoin_base.Outpoint(
        txid: tx_hash,
        index: tx_id_output_index
      )
    ],
    pubkeys: [
      bitcoin_base.ECPublic.fromHex(senders_pubKey),
    ],
  ).scanOutputs(
    paymentOwner.b_scan,    // Your scan private key
    paymentOwner.B_spend,   // Your spend public key
    [
      bitcoin_base.BitcoinScriptOutput(
        script: bitcoin_base.Script(script: [Script]),
        value: BigInt.from(amount)
      )
    ]
  );

  final scannedAddress = payto.values.first.first.address
      .toAddress(bitcoin_base.BitcoinNetwork.testnet);
  print("Found address: $scannedAddress");
}

If scannedAddress matches the taproot output → funds are yours! 🎉

What you need for scanning

Required data:

Transaction input’s txid and output_index
Sender’s public key from the output
Script and amount from the taproot address

Learn more: BIP-352 Scanning Specification

Step 4: Spend the Funds

Once confirmed, derive the private key to spend:

void main() {
  final tx_hash = "";
  final tx_id_output_index = 0;
  final senders_pubKey = "";

  bitcoin_base.ECPrivate spendPrivKey = bitcoin_base.SilentPaymentBuilder(
    vinOutpoints: [
      bitcoin_base.Outpoint(
        txid: tx_hash,
        index: tx_id_output_index
      ),
    ],
    pubkeys: [
      bitcoin_base.ECPublic.fromHex(senders_pubKey)
    ],
  ).spendOutputs(
    paymentOwner.b_scan,   // Your scan private key
    paymentOwner.b_spend   // Your spend private key
  );

  print("Private key: ${spendPrivKey}");
  // Use this to build and sign a Bitcoin transaction
}

Use spendPrivKey with Bitcoin transaction builders to create and broadcast your spending transaction.

Complete

Your Flutter app now supports Bitcoin silent payments with:

✅ Reusable static addresses
✅ Transaction privacy
✅ No notification fees
✅ Cross-platform compatibility

Additional Resources

JavaScript SDK

Node.js implementation for backend services

BIP-352 Specification

Complete technical specification

Getting started

Loyalty Program

Payment Links

Auto-Payments (Beta)

Pay Team (Beta)

Silent Payments

Stealth Addresses

Smart Contracts

@shakesco/bitcoin_base

Built With

Installation

Integration Workflow

Step 1: Generate Silent Payment Address

Step 2: Create Taproot Destination

Step 3: Scan for Incoming Funds

Step 4: Spend the Funds

Complete

Additional Resources

JavaScript SDK

BIP-352 Specification

Built With

​Installation

​Integration Workflow

​Step 1: Generate Silent Payment Address

​Step 2: Create Taproot Destination

​Step 3: Scan for Incoming Funds

​Step 4: Spend the Funds

​Complete

​Additional Resources

JavaScript SDK

BIP-352 Specification

Installation

Integration Workflow

Step 1: Generate Silent Payment Address

Step 2: Create Taproot Destination

Step 3: Scan for Incoming Funds

Step 4: Spend the Funds

Complete

Additional Resources