Private Transfers

This guide covers sending tokens privately between privacy addresses using the Privacy Boost React Native SDK.

Basic Transfer

import { PrivacyBoost } from '@sunnyside-io/privacy-boost-react-native';

const result = await sdk.send(
  '0x...token-address',
  '250000000000000000', // 0.25 tokens
  '0x04...recipient-privacy-address' // 194-char privacy address
);
console.log('Transfer TX:', result.txHash);

Transfer Parameters

Parameter	Type	Required	Description
`tokenAddress`	`string`	Yes	Token contract address
`amount`	`string`	Yes	Amount in wei (smallest unit)
`recipientPrivacyAddress`	`string`	Yes	Recipient’s 194-character privacy address

Transfer Result

interface TransferResult {
  txHash: string;  // Transaction hash
  fee: string;     // Fee paid (in wei)
}

Paying Several Recipients at Once

sendBatch pays every recipient from one set of input notes, in a single request: one fee instead of one per recipient, and one epoch slot instead of several. Output order follows the list, and the same recipient may appear more than once.

const result = await sdk.sendBatch('0x...token-address', [
  { recipient: '0x04...alice', amount: '400000000000000000' },
  { recipient: '0x04...bob', amount: '500000000000000000' },
]);
console.log('Transfer TX:', result.txHash);

How many recipients fit

The server proves a fixed set of (inputs, outputs) shapes, and a transfer has to fit inside one of them. Its output count is your recipient count plus a change note, so a longer recipient list leaves room for fewer input notes:

Outputs (recipients + change)	Input notes that can be spent
1-2	up to 15
3-11	up to 4

So 5 inputs by 3 outputs is not provable, even though 15 inputs and 11 outputs are each individually fine. In practice: past two recipients, the transfer has to be coverable by at most four notes. Consolidate fragmented notes first if a batch is rejected with UNSUPPORTED_TRANSFER_SHAPE, or split the payout across two batches.

Privacy Address Validation

Always validate the recipient’s privacy address before sending:

const isValid = sdk.isValidPrivacyAddress(recipientAddress);
if (!isValid) {
  console.log('Invalid privacy address');
  return;
}

const result = await sdk.send(tokenAddress, amount, recipientAddress);

Complete Example

import React, { useState } from 'react';
import { View, Text, TextInput, Button, ActivityIndicator } from 'react-native';
import { SdkError } from '@sunnyside-io/privacy-boost-react-native';

function TransferScreen({ sdk, tokenAddress }: { sdk: PrivacyBoost; tokenAddress: string }) {
  const [recipient, setRecipient] = useState('');
  const [amount, setAmount] = useState('');
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  const handleTransfer = async () => {
    if (!sdk.isValidPrivacyAddress(recipient)) {
      setError('Invalid privacy address');
      return;
    }

    setLoading(true);
    setError(null);

    try {
      const weiAmount = sdk.parseAmount(amount, 18);
      await sdk.send(tokenAddress, weiAmount, recipient);
      setRecipient('');
      setAmount('');
    } catch (err: any) {
      if (SdkError.SignatureRejected.instanceOf(err)) return;
      setError(err?.inner?.message ?? err?.message ?? 'Transfer failed');
    } finally {
      setLoading(false);
    }
  };

  return (
    <View style={{ padding: 16 }}>
      <TextInput
        value={recipient}
        onChangeText={setRecipient}
        placeholder="Recipient privacy address"
        editable={!loading}
      />
      <TextInput
        value={amount}
        onChangeText={setAmount}
        placeholder="Amount (e.g. 1.0)"
        keyboardType="decimal-pad"
        editable={!loading}
      />
      {error && <Text style={{ color: 'red' }}>{error}</Text>}
      {loading ? (
        <ActivityIndicator />
      ) : (
        <Button
          title="Send"
          onPress={handleTransfer}
          disabled={!recipient || !amount}
        />
      )}
    </View>
  );
}

Error Handling

try {
  await sdk.send(tokenAddress, amount, recipientPrivacyAddress);
} catch (error: any) {
  switch (error.tag) {
    case 'SignatureRejected':
      return;
    case 'InsufficientBalance':
      console.log('Not enough shielded balance');
      break;
    case 'InvalidAddress':
      console.log('Invalid privacy address');
      break;
    case 'NetworkError':
      console.log('Network error:', error.message);
      break;
    default:
      console.log('Transfer error:', error);
  }
}

Best Practices

1. Validate Inputs Before Sending

Always validate the privacy address before attempting a transfer.

2. Refresh After Transfer

await sdk.send(tokenAddress, amount, recipientPrivacyAddress);
const updatedBalance = await sdk.getBalance(tokenAddress);
console.log('Remaining shielded:', updatedBalance.shieldedBalance);

Quickstart

Setup

SDKs

Transfers

Private Transfers

Basic Transfer

Transfer Parameters

Transfer Result

Paying Several Recipients at Once

How many recipients fit

Privacy Address Validation

Complete Example

Error Handling

Best Practices

1. Validate Inputs Before Sending

2. Refresh After Transfer

Next Steps

​Private Transfers

​Basic Transfer

​Transfer Parameters

​Transfer Result

​Paying Several Recipients at Once

​How many recipients fit

​Privacy Address Validation

​Complete Example

​Error Handling

​Best Practices

​1. Validate Inputs Before Sending

​2. Refresh After Transfer

​Next Steps

Private Transfers

Basic Transfer

Transfer Parameters

Transfer Result

Paying Several Recipients at Once

How many recipients fit

Privacy Address Validation

Complete Example

Error Handling

Best Practices

1. Validate Inputs Before Sending

2. Refresh After Transfer

Next Steps