class Bitcoin::ExtKey

BIP32 Extended private key

Constants

MASTER_FINGERPRINT
MAX_DEPTH

Attributes

chain_code[RW]
depth[RW]
key[RW]
number[RW]
parent_fingerprint[RW]
ver[RW]

Public Class Methods

from_base58(base58) click to toggle source

import private key from Base58 private key address

# File lib/bitcoin/ext_key.rb, line 163
def self.from_base58(base58)
  ExtKey.parse_from_payload(ExtPubkey.validate_base58(base58))
end
generate_master(seed) click to toggle source

generate master key from seed. @params [String] seed a seed data with hex format.

# File lib/bitcoin/ext_key.rb, line 23
def self.generate_master(seed)
  ext_key = ExtKey.new
  ext_key.depth = ext_key.number = 0
  ext_key.parent_fingerprint = MASTER_FINGERPRINT
  l = Bitcoin.hmac_sha512('Bitcoin seed', seed.htb)
  left = l[0..31].bth.to_i(16)
  raise 'invalid key' if left >= CURVE_ORDER || left == 0
  ext_key.key = Bitcoin::Key.new(priv_key: l[0..31].bth, key_type: Bitcoin::Key::TYPES[:compressed])
  ext_key.chain_code = l[32..-1]
  ext_key
end
parse_from_payload(payload) click to toggle source
# File lib/bitcoin/ext_key.rb, line 143
def self.parse_from_payload(payload)
  buf = StringIO.new(payload)
  ext_key = ExtKey.new
  ext_key.ver = buf.read(4).bth # version
  raise ArgumentError, Errors::Messages::INVALID_BIP32_VERSION unless ExtKey.support_version?(ext_key.ver)
  ext_key.depth = buf.read(1).unpack1('C')
  ext_key.parent_fingerprint = buf.read(4).bth
  ext_key.number = buf.read(4).unpack1('N')
  if ext_key.depth == 0
    raise ArgumentError, Errors::Messages::INVALID_BIP32_FINGERPRINT unless ext_key.parent_fingerprint == ExtKey::MASTER_FINGERPRINT
    raise ArgumentError, Errors::Messages::INVALID_BIP32_ZERO_INDEX if ext_key.number > 0
  end
  raise ArgumentError, Errors::Messages:: INVALID_BIP32_ZERO_DEPTH if ext_key.parent_fingerprint == ExtKey::MASTER_FINGERPRINT && ext_key.depth > 0
  ext_key.chain_code = buf.read(32)
  raise ArgumentError, Errors::Messages::INVALID_BIP32_PRIV_PREFIX unless buf.read(1).bth == '00' # 0x00
  ext_key.key = Bitcoin::Key.new(priv_key: buf.read(32).bth, key_type: Bitcoin::Key::TYPES[:compressed])
  ext_key
end
support_version?(version) click to toggle source

check whether version is supported version bytes.

# File lib/bitcoin/ext_key.rb, line 181
def self.support_version?(version)
  p = Bitcoin.chain_params
  [p.bip49_privkey_p2wpkh_p2sh_version, p.bip84_privkey_p2wpkh_version, p.extended_privkey_version].include?(version)
end
version_from_purpose(purpose) click to toggle source

get version bytes from purpose' value.

# File lib/bitcoin/ext_key.rb, line 168
def self.version_from_purpose(purpose)
  v = purpose - Bitcoin::HARDENED_THRESHOLD
  case v
    when 49
      Bitcoin.chain_params.bip49_privkey_p2wpkh_p2sh_version
    when 84
      Bitcoin.chain_params.bip84_privkey_p2wpkh_version
    else
      Bitcoin.chain_params.extended_privkey_version
  end
end

Public Instance Methods

==(other) click to toggle source
# File lib/bitcoin/ext_key.rb, line 139
def ==(other)
  to_payload == other.to_payload
end
addr() click to toggle source

get address

# File lib/bitcoin/ext_key.rb, line 73
def addr
  ext_pubkey.addr
end
derive(number, harden = false) click to toggle source

derive new key @param [Integer] number a child index @param [Boolean] harden whether hardened key or not. If true, 2^31 is added to number. @return [Bitcoin::ExtKey] derived new key.

# File lib/bitcoin/ext_key.rb, line 96
def derive(number, harden = false)
  number += Bitcoin::HARDENED_THRESHOLD if harden
  new_key = ExtKey.new
  new_key.depth = depth + 1
  raise IndexError, 'Depth over 255.' if new_key.depth > MAX_DEPTH
  new_key.number = number
  new_key.parent_fingerprint = fingerprint
  if number > (Bitcoin::HARDENED_THRESHOLD - 1)
    data = [0x00].pack('C') << key.priv_key.htb << [number].pack('N')
  else
    data = key.pubkey.htb << [number].pack('N')
  end
  l = Bitcoin.hmac_sha512(chain_code, data)
  left = l[0..31].bth.to_i(16)
  raise 'invalid key' if left >= CURVE_ORDER
  child_priv = (left + key.priv_key.to_i(16)) % CURVE_ORDER
  raise 'invalid key ' if child_priv >= CURVE_ORDER
  new_key.key = Bitcoin::Key.new(
      priv_key: child_priv.to_even_length_hex.rjust(64, '0'), key_type: key_type)
  new_key.chain_code = l[32..-1]
  new_key.ver = version
  new_key
end
ext_pubkey() click to toggle source

get ExtPubkey from priv_key

# File lib/bitcoin/ext_key.rb, line 36
def ext_pubkey
  k = ExtPubkey.new
  k.depth = depth
  k.number = number
  k.parent_fingerprint = parent_fingerprint
  k.chain_code = chain_code
  k.pubkey = key.pubkey
  k.ver = priv_ver_to_pub_ver
  k
end
fingerprint() click to toggle source

get fingerprint

# File lib/bitcoin/ext_key.rb, line 83
def fingerprint
  identifier.slice(0..7)
end
hardened?() click to toggle source

whether hardened key.

# File lib/bitcoin/ext_key.rb, line 88
def hardened?
  number >= Bitcoin::HARDENED_THRESHOLD
end
hash160() click to toggle source
# File lib/bitcoin/ext_key.rb, line 68
def hash160
  Bitcoin.hash160(pub)
end
identifier() click to toggle source

get key identifier

# File lib/bitcoin/ext_key.rb, line 78
def identifier
  Bitcoin.hash160(key.pubkey)
end
key_type() click to toggle source

get key type defined by BIP-178 using version.

# File lib/bitcoin/ext_key.rb, line 127
def key_type
  v = version
  case v
  when Bitcoin.chain_params.bip49_privkey_p2wpkh_p2sh_version
    Bitcoin::Key::TYPES[:p2wpkh_p2sh]
  when Bitcoin.chain_params.bip84_privkey_p2wpkh_version
    Bitcoin::Key::TYPES[:p2wpkh]
  when Bitcoin.chain_params.extended_privkey_version
    Bitcoin::Key::TYPES[:compressed]
  end
end
priv() click to toggle source

get private key(hex)

# File lib/bitcoin/ext_key.rb, line 59
def priv
  key.priv_key
end
priv_ver_to_pub_ver() click to toggle source

convert privkey version to pubkey version

# File lib/bitcoin/ext_key.rb, line 187
def priv_ver_to_pub_ver
  case version
    when Bitcoin.chain_params.bip49_privkey_p2wpkh_p2sh_version
      Bitcoin.chain_params.bip49_pubkey_p2wpkh_p2sh_version
    when Bitcoin.chain_params.bip84_privkey_p2wpkh_version
      Bitcoin.chain_params.bip84_pubkey_p2wpkh_version
    else
      Bitcoin.chain_params.extended_pubkey_version
  end
end
pub() click to toggle source

get public key(hex)

# File lib/bitcoin/ext_key.rb, line 64
def pub
  key.pubkey
end
to_base58() click to toggle source

Base58 encoded extended private key

# File lib/bitcoin/ext_key.rb, line 54
def to_base58
  ExtPubkey.encode_base58(to_hex)
end
to_payload() click to toggle source

serialize extended private key

# File lib/bitcoin/ext_key.rb, line 48
def to_payload
  version.htb << [depth].pack('C') << parent_fingerprint.htb <<
      [number].pack('N') << chain_code << [0x00].pack('C') << key.priv_key.htb
end
version() click to toggle source

get version bytes using serialization format

# File lib/bitcoin/ext_key.rb, line 121
def version
  return ExtKey.version_from_purpose(number) if depth == 1
  ver ? ver : Bitcoin.chain_params.extended_privkey_version
end