Silent Payments (BIP352) Testing Guide

This guide assumes you have a basic knowledge of the command line and are familiar with the bitcoin-cli RPC client.

Setup (optional)

While not required, this guide was written using a bendir directory for easier testing. If you want to follow the guide without using bendir, it's recommended you alias bitcoin-cli to bitcoin-cli -named -signet -datadir=<your testing datadir> so you can copy-paste the commands directly from the guide. To use bendir for your testing environment:

git clone https://github.com/josibake/bendir.git
cp -r bendir silent-payments-testing
cd ~/silent-payments-testing
direnv allow

If this is your first time building Bitcoin Core from source, take a look at the build instructions for your system (build-*.md in bitcoin/doc/). Once you're ready to build, checkout and compile #28453:

# in your bitcoin src directory
git fetch upstream pull/28453/head:silent-payments-testing-branch
git checkout silent-payments-testing-branch

# assuming you have the build dependencies installed
./autogen.sh
./configure
make

Once the build has finished, copy the binaries into your testing directory:

cp ~/bitcoin/src/bitcoind ~/silent-payments-testing/bin/
cp ~/bitcoin/src/bitcoin-cli ~/silent-payments-testing/bin/

Start bitcoind on signet/regtest:

cd ~/silent-payments-testing
init signet
bitcoind -daemon

You are now ready to start testing!

Create and fund a silent payments wallet

Create a wallet:

bitcoin-cli createwallet "sp" silent_payments=true

Fund the wallet:

# mine some blocks if using regtest or get some coins from a signet faucet
bitcoin-cli getnewaddress
# can use https://signet.bc-2.jp or your faucet of choice to send coins to the address

Make a silent payment!

# you can use include_unsafe (instead of waiting for a block) if your signet coins are still unconfirmed
bitcoin-cli getnewaddress address_type="silent-payment"
bitcoin-cli sendtoaddress "<your silent payment address>" <amount> include_unsafe=true

Check the transaction:

bitcoin-cli gettransaction "txid" verbose=true

Silent payment usernames

While silent payments is primarily a privacy improvement, it is also a UX improvment for Bitcoin and can enable cool new protocols like usernames for sending Bitcoin. Here is a small script to demonstrate:

#!/bin/bash

# Default to mainnet if no argument is provided
NETWORK="mainnet"

# Help text
display_help() {
    echo "Usage: $0 [OPTION] EMAIL"
    echo "Fetch payment information for a given email address."
    echo ""
    echo "Available options:"
    echo "  -signet, -regtest, -testnet, -mainnet  Specify the network (default: mainnet)"
    echo "  -h, --help                             Display this help and exit"
    exit 0
}

# Function to check and set the network
set_network() {
    case $1 in
        -signet|-regtest|-testnet|-mainnet)
            NETWORK="${1#-}"
            return 0
            ;;
        -h|--help)
            display_help
            ;;
        *)
            return 1
            ;;
    esac
}

# If no arguments are provided, display help
if [ "$#" -eq 0 ]; then
    display_help
fi

# Check the first and second arguments for the network flag or help
if ! set_network $1; then
    set_network $2
    EMAIL_ARG=$1
else
    EMAIL_ARG=$2
fi

read user domain < <(echo $EMAIL_ARG | awk -F@ '{print $1, $2}')

# Fetch the JSON and check if the network exists in the structure
JSON=$(curl --max-time 3 -s -f https://$domain/.well-known/silent-payments/$user)
CURL_EXIT_STATUS=$?

if [ $CURL_EXIT_STATUS -ne 0 ]; then
    echo "Error: Failed to fetch data from https://$domain/.well-known/silent-payments/$user"
    echo "Are you sure $user@$domain has a silent payment address configured?"
    exit 1
fi

if ! echo "$JSON" | jq -e --arg network "$NETWORK" 'has($network)' > /dev/null; then
    echo "Error: $user does not have a $NETWORK silent payment address. Try one of:"
    echo $JSON | jq
    exit 1
fi

# Extract the value for the provided network
echo "$JSON" | jq -r --arg network "$NETWORK" '.[$network]'

If you don't understand the script that's okay. This script takes an email address and a network flag and fetches a silent payment address from the .well-known directory of the domain. To use the script:

# if using bendir, this script is already available in aliases.
# otherwise, save the script in a file called `pay` and make it executable
vim pay
# copy the script
chmod +x pay

If you have a domain, you can put your silent payments address under the well-known directory like so:

# find the .well-known directory on your server and create a file at the following path
USERNAME="your_desired_username"
SILENT_PAYMENT_ADDRESS="your_silent_payment_address_here"
mkdir -p .well-known/silent-payments

# Echo the JSON content into the file
echo "{\"signet\": \"$SILENT_PAYMENT_ADDRESS\"}" > .well-known/silent-payments/$USERNAME

Now you can get your silent payment address with the pay script:

pay user@domain -signet

And you can make payments from the command line:

bitcoin-cli sendtoaddress $(pay [email protected] -signet) <amount>

Further testing

Try using different RPCs, like send
Send to the same silent payment address multiple times and verify the addresses are different each time
Send multiple UTXOs to the same address, then spend from that address multiple times and verify the silent payment outputs are always unique
Verify you can detect an incoming silent payment in the mempool and in a block
Verify you can detect previous silent payments when doing a wallet rescan

If you run into any issues or have questions, feel free to leave a comment on this gist!

josibake/silent-payments-testing.md

Silent Payments (BIP352) Testing Guide

Setup (optional)

Create and fund a silent payments wallet

Silent payment usernames

Further testing