defmodule BitcoinLib.Key.PublicKey do
@moduledoc """
Bitcoin extended public key management module
"""
require Integer
@enforce_keys [:key]
defstruct [
:key,
:uncompressed_key,
:chain_code,
depth: 0,
index: 0,
parent_fingerprint: <<0::32>>,
fingerprint: <<0::32>>
]
alias BitcoinLib.Key.PublicKey.{
ChildFromIndex,
ChildFromDerivationPath,
Serialization,
Deserialization
}
alias BitcoinLib.{Address, Crypto}
alias BitcoinLib.Key.{PrivateKey, PublicKey}
alias BitcoinLib.Key.HD.{DerivationPath, Fingerprint}
@doc """
Derives an extended public key from an extended private key. Happens to be the same process
as for regular keys.
Inspired by https://learnmeabitcoin.com/technical/hd-wallets#master-private-key
## Examples
iex> %BitcoinLib.Key.PrivateKey{
...> key: <<0x081549973BAFBBA825B31BCC402A3C4ED8E3185C2F3A31C75E55F423E9629AA3::264>>,
...> chain_code: <<0x1D7D2A4C940BE028B945302AD79DD2CE2AFE5ED55E1A2937A5AF57F8401E73DD::256>>
...> }
...> |> BitcoinLib.Key.PublicKey.from_private_key()
%BitcoinLib.Key.PublicKey{
fingerprint: <<0xED104CB8::32>>,
key: <<0x0343B337DEC65A47B3362C9620A6E6FF39A1DDFA908ABAB1666C8A30A3F8A7CCCC::264>>,
uncompressed_key: <<0x0443b337dec65a47b3362c9620a6e6ff39a1ddfa908abab1666c8a30a3f8a7ccccfc24a7914950b6405729a9313cec6ae5bb4a082f92d05ac49df4b6dd8387bfeb::520>>,
chain_code: <<0x1D7D2A4C940BE028B945302AD79DD2CE2AFE5ED55E1A2937A5AF57F8401E73DD::256>>,
depth: 0,
index: 0,
parent_fingerprint: <<0::32>>
}
"""
@spec from_private_key(%PrivateKey{}) :: %PublicKey{}
def from_private_key(%PrivateKey{} = private_key) do
{uncompressed, compressed} =
private_key.key
|> extract_from_private_key()
%PublicKey{
key: compressed,
uncompressed_key: uncompressed,
chain_code: private_key.chain_code,
depth: private_key.depth,
index: private_key.index,
parent_fingerprint: private_key.parent_fingerprint
}
|> add_fingerprint()
end
@doc """
Converts the public key to an address of the type specified as the second parameter
Defaults to bech32 address type
## Examples
iex> %BitcoinLib.Key.PublicKey{
...> key: <<0x3EB181FB7B5CF63D82307188B20828B83008F2D2511E5C6EDCBE171C63DD2CBC1::264>>,
...> chain_code: <<0x581F15490635CF8CD0AEEF556562F52C60179E0E87E0EA92977E364D949DC2E4::256>>,
...> depth: 0x5,
...> index: 0x0
...> }
...> |> BitcoinLib.Key.PublicKey.to_address(:p2pkh)
"1BRjWnoAVg3EASJHex5YeyDWC1zZ4CA5vc"
"""
@spec to_address(%PublicKey{}, :p2pkh | :p2sh | :p2wpkh) :: binary()
def to_address(%PublicKey{} = public_key, type \\ :p2wpkh, network \\ :mainnet) do
public_key
|> Address.from_public_key(type, network)
end
@doc """
Creates a public key hash
## Examples
iex> %BitcoinLib.Key.PublicKey{
...> key: <<0x02b4632d08485ff1df2db55b9dafd23347d1c47a457072a1e87be26896549a8737::264>>
...> }
...> |> BitcoinLib.Key.PublicKey.hash()
<<0x93ce48570b55c42c2af816aeaba06cfee1224fae::160>>
"""
@spec hash(%PublicKey{}) :: <<_::160>>
def hash(%PublicKey{key: key}) do
Crypto.hash160(key)
end
@doc """
Serialization of a master public key into its xpub version
values from https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#test-vector-1
## Examples
iex> %BitcoinLib.Key.PublicKey{
...> key: <<0x339A36013301597DAEF41FBE593A02CC513D0B55527EC2DF1050E2E8FF49C85C2::264>>,
...> chain_code: <<0x873DFF81C02F525623FD1FE5167EAC3A55A049DE3D314BB42EE227FFED37D508::256>>,
...> depth: 0,
...> index: 0,
...> parent_fingerprint: <<0::32>>
...> }
...> |> BitcoinLib.Key.PublicKey.serialize()
{
:ok,
"xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8"
}
"""
@spec serialize(%PublicKey{}, :mainnet | :testnet, :bip32 | :bip49 | :bip84) ::
{:ok, binary()} | {:error, binary()}
def serialize(public_key, network \\ :mainnet, format \\ :bip32) do
Serialization.serialize(public_key, network, format)
end
@doc """
Serialization of a master public key into its xpub version
values from https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#test-vector-1
## Examples
iex> %BitcoinLib.Key.PublicKey{
...> key: <<0x339A36013301597DAEF41FBE593A02CC513D0B55527EC2DF1050E2E8FF49C85C2::264>>,
...> chain_code: <<0x873DFF81C02F525623FD1FE5167EAC3A55A049DE3D314BB42EE227FFED37D508::256>>,
...> depth: 0,
...> index: 0,
...> parent_fingerprint: <<0::32>>
...> }
...> |> BitcoinLib.Key.PublicKey.serialize!()
"xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8"
"""
@spec serialize!(%PublicKey{}, :mainnet | :testnet, :bip32 | :bip49 | :bip84) :: binary()
def serialize!(public_key, network \\ :mainnet, format \\ :bip32) do
case serialize(public_key, network, format) do
{:ok, serialized} -> serialized
{:error, message} -> raise message
end
end
@doc """
Deserialization of a public key from its xpub version
values from https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#test-vector-1
## Examples
iex> "xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8"
...> |> BitcoinLib.Key.PublicKey.deserialize()
{
:ok,
%BitcoinLib.Key.PublicKey{
fingerprint: <<0x3442193E::32>>,
key: <<0x339A36013301597DAEF41FBE593A02CC513D0B55527EC2DF1050E2E8FF49C85C2::264>>,
chain_code: <<0x873DFF81C02F525623FD1FE5167EAC3A55A049DE3D314BB42EE227FFED37D508::256>>,
depth: 0,
index: 0,
parent_fingerprint: <<0::32>>
},
:mainnet,
:bip32
}
"""
@spec deserialize(binary()) ::
{:ok, %PublicKey{}, :mainnet | :testnet, :bip32 | :bip49 | :bip84}
| {:error, String.t()}
def deserialize(serialized_public_key) do
case Deserialization.deserialize(serialized_public_key) do
{:ok, public_key, network, format} ->
{:ok, public_key |> add_fingerprint(), network, format}
{:error, message} ->
{:error, message}
end
end
@doc """
Deserialization of a public key from its xpub version
values from https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#test-vector-1
## Examples
iex> "xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8"
...> |> BitcoinLib.Key.PublicKey.deserialize!()
%BitcoinLib.Key.PublicKey{
fingerprint: <<0x3442193E::32>>,
key: <<0x339A36013301597DAEF41FBE593A02CC513D0B55527EC2DF1050E2E8FF49C85C2::264>>,
chain_code: <<0x873DFF81C02F525623FD1FE5167EAC3A55A049DE3D314BB42EE227FFED37D508::256>>,
depth: 0,
index: 0,
parent_fingerprint: <<0::32>>
}
"""
@spec deserialize!(binary()) :: %PublicKey{}
def deserialize!(serialized_public_key) do
with {:ok, public_key, _network, _format} <- deserialize(serialized_public_key) do
public_key
else
{:error, message} -> raise message
end
end
@doc """
Derives the nth child of a HD public key
Takes a public key, its chain code and the child's index
Returns the child's public key and it's associated chain code
Inspired by https://learnmeabitcoin.com/technical/extended-keys#child-extended-key-derivation
## Examples
iex> public_key = %BitcoinLib.Key.PublicKey{
...> key: <<0x252C616D91A2488C1FD1F0F172E98F7D1F6E51F8F389B2F8D632A8B490D5F6DA9::264>>,
...> chain_code: <<0x463223AAC10FB13F291A1BC76BC26003D98DA661CB76DF61E750C139826DEA8B::256>>
...> }
...> index = 0
...> BitcoinLib.Key.PublicKey.derive_child(public_key, index)
{
:ok,
%BitcoinLib.Key.PublicKey{
key: <<0x30204D3503024160E8303C0042930EA92A9D671DE9AA139C1867353F6B6664E59::264>>,
chain_code: <<0x05AAE71D7C080474EFAAB01FA79E96F4C6CFE243237780B0DF4BC36106228E31::256>>,
depth: 1,
index: 0,
parent_fingerprint: <<0x18C1259::32>>,
fingerprint: <<0x9680603F::32>>
}
}
"""
@spec derive_child(%PublicKey{}, integer()) :: {:ok, %PublicKey{}} | {:error, binary()}
def derive_child(public_key, index) do
ChildFromIndex.get(public_key, index)
end
@doc """
Simply calls from_derivation_path and directly returns the public key whatever the outcome.any()
Will crash if the index is negative or greater than 0x7FFFFFFF
## Examples
iex> public_key = %BitcoinLib.Key.PublicKey{
...> key: <<0x252C616D91A2488C1FD1F0F172E98F7D1F6E51F8F389B2F8D632A8B490D5F6DA9::264>>,
...> chain_code: <<0x463223AAC10FB13F291A1BC76BC26003D98DA661CB76DF61E750C139826DEA8B::256>>
...> }
...> index = 0
...> BitcoinLib.Key.PublicKey.derive_child!(public_key, index)
%BitcoinLib.Key.PublicKey{
key: <<0x30204D3503024160E8303C0042930EA92A9D671DE9AA139C1867353F6B6664E59::264>>,
chain_code: <<0x05AAE71D7C080474EFAAB01FA79E96F4C6CFE243237780B0DF4BC36106228E31::256>>,
depth: 1,
index: 0,
parent_fingerprint: <<0x18C1259::32>>,
fingerprint: <<0x9680603F::32>>
}
"""
@spec derive_child!(%PublicKey{}, integer()) :: %PublicKey{}
def derive_child!(public_key, index) do
derive_child(public_key, index)
|> elem(1)
end
@doc """
Derives a child public key, following a derivation path
## Examples
iex> public_key = %BitcoinLib.Key.PublicKey{
...> key: <<0x252C616D91A2488C1FD1F0F172E98F7D1F6E51F8F389B2F8D632A8B490D5F6DA9::264>>,
...> chain_code: <<0x463223AAC10FB13F291A1BC76BC26003D98DA661CB76DF61E750C139826DEA8B::256>>
...> }
...> {:ok, derivation_path} = BitcoinLib.Key.HD.DerivationPath.parse("M/44'/0'/0'/0/0")
...> BitcoinLib.Key.PublicKey.from_derivation_path(public_key, derivation_path)
{
:ok,
%BitcoinLib.Key.PublicKey{
key: <<0x29DCAFD0D7D67B13657CC9EE7C8976E141F20F0684BF3FC83CAF068E74186BCDC::264>>,
chain_code: <<0x162EEE68F7C3823CAF8BD2615A4A33633673CAAB66FF6F338FB0653FC59D462D::256>>,
depth: 5,
index: 0,
parent_fingerprint: <<0xCA2A5281::32>>,
fingerprint: <<0xAEAAB1AD::32>>
}
}
"""
@spec from_derivation_path(%PublicKey{}, %DerivationPath{}) :: {:ok, %PublicKey{}}
def from_derivation_path(%PublicKey{} = public_key, %DerivationPath{} = derivation_path) do
ChildFromDerivationPath.get(public_key, derivation_path)
end
@doc """
Checks a signature against a public key
## Examples
iex> message = <<0xf05750d5bd2c2b4bbbd57cb07082ba5aabb41863e33bf2cd187a9adb1443dbc3::256>>
...> public_key = %BitcoinLib.Key.PublicKey{
...> key: <<0x03f0e5a53db9f85e5b2eecf677925ffe21dd1409bcfe9a0730404053599b0901e5::264>>
...> }
...> <<0x30440220032a1544f599bf29981851e826e8a6f7c036958ba3543cf9778a0756dfc425f6022067eec131c0d73825633c0fddce1abfb14bb26bc9e0d6e9d644a77361f74cb55c::560>>
...> |> BitcoinLib.Key.PublicKey.validate_signature(message, public_key)
true
"""
@spec validate_signature(bitstring(), bitstring(), %PublicKey{}) :: boolean()
def validate_signature(signature, message, %PublicKey{} = public_key) do
Crypto.Secp256k1.validate(signature, message, public_key)
end
@doc """
Returns a compressed version of an uncompressed public key
## Examples
iex> <<0x0411DB93E1DCDB8A016B49840F8C53BC1EB68A382E97B1482ECAD7B148A6909A5CB2E0EADDFB84CCF9744464F82E160BFA9B8B64F9D4C03F999B8643F656B412A3::520>>
...> |> BitcoinLib.Key.PublicKey.compress()
<<0x0211db93e1dcdb8a016b49840f8c53bc1eb68a382e97b1482ecad7b148a6909a5c::264>>
"""
@spec compress(<<_::520>>) :: <<_::264>>
def compress(<<prefix::8, x::bitstring-256, _::bitstring-256>>) do
case Integer.is_even(prefix) do
true -> <<2::8, x::bitstring-256>>
false -> <<3::8, x::bitstring-256>>
end
end
defp add_fingerprint(%PublicKey{} = public_key) do
public_key
|> Map.put(:fingerprint, Fingerprint.compute(public_key))
end
defp extract_from_private_key(private_key) when is_bitstring(private_key) do
public_uncompressed = Crypto.secp256k1(private_key)
compressed = get_compressed(public_uncompressed)
{
public_uncompressed,
compressed
}
end
defp get_compressed(public_uncompressed) do
first_char =
public_uncompressed
|> get_first_char
compressed_body =
public_uncompressed
|> Binary.part(1, 32)
first_char <> compressed_body
end
defp get_first_char(public_uncompressed) do
reminder =
public_uncompressed
|> Binary.last()
|> rem(2)
case reminder do
0 -> <<2>>
1 -> <<3>>
end
end
end
defimpl Inspect, for: BitcoinLib.Key.PublicKey do
alias BitcoinLib.Formatting.HexBinary
def inspect(%BitcoinLib.Key.PublicKey{} = public_key, opts) do
%{
public_key
| key: %HexBinary{data: public_key.key},
uncompressed_key:
case public_key.uncompressed_key do
nil -> nil
_ -> %HexBinary{data: public_key.uncompressed_key}
end,
chain_code:
case public_key.chain_code do
nil -> nil
_ -> %HexBinary{data: public_key.chain_code}
end,
fingerprint:
case public_key.fingerprint do
nil -> nil
_ -> %HexBinary{data: public_key.fingerprint}
end,
parent_fingerprint:
case public_key.parent_fingerprint do
nil -> nil
_ -> %HexBinary{data: public_key.parent_fingerprint}
end
}
|> Inspect.Any.inspect(opts)
end
end
