defmodule BitcoinLib.Address do
@moduledoc """
Bitcoin address management
Inspired by https://learnmeabitcoin.com/technical/public-key-hash
"""
require Logger
alias BitcoinLib.Crypto
alias BitcoinLib.Key.PublicKey
alias BitcoinLib.Address.{P2PKH, P2SH, Bech32}
@doc """
Turns a public key into an address of the specified format
## Examples
iex> %BitcoinLib.Key.PublicKey{
...> key: <<0x0343B337DEC65A47B3362C9620A6E6FF39A1DDFA908ABAB1666C8A30A3F8A7CCCC::264>>
...> }
...> |> BitcoinLib.Address.from_public_key(:p2wpkh, :mainnet)
"bc1qa5gyew808tdta3wjh6qh3jvcglukjsnfg0qx4u"
"""
@spec from_public_key(%PublicKey{}, :p2pkh | :p2sh | :p2wpkh, :mainnet | :testnet) ::
binary()
def from_public_key(public_key, script_type, network \\ :mainnet)
def from_public_key(%PublicKey{} = public_key, :p2pkh, :mainnet),
do: P2PKH.from_public_key(public_key)
def from_public_key(%PublicKey{} = public_key, :p2pkh, :testnet),
do: P2PKH.from_public_key(public_key, :testnet)
def from_public_key(%PublicKey{} = public_key, :p2sh, :mainnet),
do: P2SH.from_public_key(public_key)
def from_public_key(%PublicKey{} = public_key, :p2sh, :testnet),
do: P2SH.from_public_key(public_key, :testnet)
def from_public_key(%PublicKey{} = public_key, :p2wpkh, :mainnet),
do: Bech32.from_public_key(public_key)
def from_public_key(%PublicKey{} = public_key, :p2wpkh, :testnet),
do: Bech32.from_public_key(public_key, :testnet)
@doc """
Convert public key hash into a P2PKH Bitcoin address.
Details can be found here: https://en.bitcoin.it/wiki/Technical_background_of_version_1_Bitcoin_addresses
## Examples
iex> <<0x6ae201797de3fa7d1d95510f50c1a9c50ce4cc36::160>>
...> |> BitcoinLib.Address.from_public_key_hash()
"1Ak9NVPmwCHEpsSWvM6cNRC7dsYniRmwMG"
"""
@spec from_public_key_hash(binary(), :mainnet | :testnet) :: bitstring()
def from_public_key_hash(public_key_hash, network \\ :mainnet) do
P2PKH.from_public_key_hash(public_key_hash, network)
end
def from_script_hash(public_key_hash, network \\ :mainnet) do
P2SH.from_script_hash(public_key_hash, network)
end
@doc """
Applies the address's checksum to make sure it's valid
## Examples
iex> "tb1qxrd42xz49clfrs5mz6thglwlu5vxmdqxsvpnks"
...> |> BitcoinLib.Address.valid?()
true
"""
@spec valid?(binary()) :: boolean()
def valid?("1" <> _ = address) do
P2PKH.valid?(address)
end
def valid?("m" <> _ = address) do
P2PKH.valid?(address)
end
def valid?("2" <> _ = address) do
P2SH.valid?(address)
end
def valid?("3" <> _ = address) do
P2SH.valid?(address)
end
def valid?("tb1" <> _ = address) do
Bech32.valid?(address)
end
def valid?("bc1" <> _ = address) do
Bech32.valid?(address)
end
def valid?(address) do
Logger.error("#{address} is of an unknown address type")
end
@doc """
Extracts the public key hash from an address, and make sure the checkum is ok
## Examples
iex> address = "tb1qxrd42xz49clfrs5mz6thglwlu5vxmdqxsvpnks"
...> BitcoinLib.Address.destructure(address)
{:ok, <<0x30db5518552e3e91c29b1697747ddfe5186db406::160>>, :p2wpkh, :testnet}
iex> address = "mwYKDe7uJcgqyVHJAPURddeZvM5zBVQj5L"
...> BitcoinLib.Address.destructure(address)
{:ok, <<0xafc3e518577316386188af748a816cd14ce333f2::160>>, :p2pkh, :testnet}
"""
@spec destructure(binary()) ::
{:ok, <<_::272>> | <<_::160>>, :p2pkh | :p2sh | :p2wpkh, :mainnet | :testnet}
| {:error, binary()}
def destructure("bc1" <> _ = bech32_address), do: Bech32.destructure(bech32_address)
def destructure("tb1" <> _ = bech32_address), do: Bech32.destructure(bech32_address)
def destructure(address) do
<<prefix::8, public_key_hash::bitstring-160, checksum::bitstring-32>> =
address
|> Base58.decode()
{address_type, network} = get_address_type_from_prefix(prefix)
case test_checksum(prefix, public_key_hash, checksum) do
{:ok} -> {:ok, public_key_hash, address_type, network}
{:error, message} -> {:error, message}
end
end
@spec test_checksum(integer(), bitstring(), bitstring()) :: {:ok} | {:error, binary()}
defp test_checksum(prefix, public_key_hash, original_checksum) do
calculated_checksum =
<<prefix::8, public_key_hash::bitstring-160>>
|> Crypto.checksum()
case calculated_checksum do
^original_checksum -> {:ok}
_ -> {:error, "checksums don't match"}
end
end
# example 17VZNX1SN5NtKa8UQFxwQbFeFc3iqRYhem
defp get_address_type_from_prefix(0), do: {:p2pkh, :mainnet}
# example 3EktnHQD7RiAE6uzMj2ZifT9YgRrkSgzQX
defp get_address_type_from_prefix(5), do: {:p2sh, :mainnet}
# example mipcBbFg9gMiCh81Kj8tqqdgoZub1ZJRfn
defp get_address_type_from_prefix(111), do: {:p2pkh, :testnet}
# example 2MzQwSSnBHWHqSAqtTVQ6v47XtaisrJa1Vc
defp get_address_type_from_prefix(196), do: {:p2sh, :testnet}
defp get_address_type_from_prefix(_), do: :unknown
end