Class: Bitcoin::ExtKey

Inherits:
Object
  • Object
show all
Includes:
HexConverter
Defined in:
lib/bitcoin/ext_key.rb

Overview

BIP32 Extended private key

Direct Known Subclasses

PaymentCode

Constant Summary collapse

MAX_DEPTH = 
255
MASTER_FINGERPRINT = 
'00000000'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from HexConverter

#to_hex

Instance Attribute Details

#chain_code ⇒ Object

Returns the value of attribute chain_code.



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# File 'lib/bitcoin/ext_key.rb', line 17

def chain_code
  @chain_code
end

#depth ⇒ Object

Returns the value of attribute depth.



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# File 'lib/bitcoin/ext_key.rb', line 15

def depth
  @depth
end

#key ⇒ Object

Bitcoin::Key



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# File 'lib/bitcoin/ext_key.rb', line 18

def key
  @key
end

#number ⇒ Object

Returns the value of attribute number.



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# File 'lib/bitcoin/ext_key.rb', line 16

def number
  @number
end

#parent_fingerprint ⇒ Object

Returns the value of attribute parent_fingerprint.



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# File 'lib/bitcoin/ext_key.rb', line 19

def parent_fingerprint
  @parent_fingerprint
end

#ver ⇒ Object

Returns the value of attribute ver.



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# File 'lib/bitcoin/ext_key.rb', line 14

def ver
  @ver
end

Class Method Details

.from_base58(base58) ⇒ Object

import private key from Base58 private key address



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# File 'lib/bitcoin/ext_key.rb', line 164

def self.from_base58(base58)
  ExtKey.parse_from_payload(ExtPubkey.validate_base58(base58))
end

.generate_master(seed) ⇒ Object

generate master key from seed.



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# 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
  l_priv = ECDSA::Format::IntegerOctetString.encode(left, 32)
  ext_key.key = Bitcoin::Key.new(priv_key: l_priv.bth, key_type: Bitcoin::Key::TYPES[:compressed])
  ext_key.chain_code = l[32..-1]
  ext_key
end

.parse_from_payload(payload) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/bitcoin/ext_key.rb', line 144

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) ⇒ Boolean

check whether version is supported version bytes.

Returns:

  • (Boolean) 


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# File 'lib/bitcoin/ext_key.rb', line 182

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) ⇒ Object

get version bytes from purpose’ value.



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# File 'lib/bitcoin/ext_key.rb', line 169

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

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/bitcoin/ext_key.rb', line 140

def ==(other)
  to_payload == other.to_payload
end

#addr ⇒ Object

get address



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# File 'lib/bitcoin/ext_key.rb', line 74

def addr
  ext_pubkey.addr
end

#derive(number, harden = false) ⇒ Bitcoin::ExtKey

derive new key

Parameters:

  • number (Integer) —

    a child index

  • harden (Boolean) (defaults to: false) —

    whether hardened key or not. If true, 2^31 is added to number.

Returns:

Raises:

  • (IndexError) 


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# File 'lib/bitcoin/ext_key.rb', line 97

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
  child_priv = ECDSA::Format::IntegerOctetString.encode(child_priv, 32)
  new_key.key = Bitcoin::Key.new(priv_key: child_priv.bth, key_type: key_type)
  new_key.chain_code = l[32..-1]
  new_key.ver = version
  new_key
end

#ext_pubkey ⇒ Object

get ExtPubkey from priv_key



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# File 'lib/bitcoin/ext_key.rb', line 37

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 ⇒ Object

get fingerprint



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# File 'lib/bitcoin/ext_key.rb', line 84

def fingerprint
  identifier.slice(0..7)
end

#hardened? ⇒ Boolean

whether hardened key.

Returns:

  • (Boolean) 


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# File 'lib/bitcoin/ext_key.rb', line 89

def hardened?
  number >= Bitcoin::HARDENED_THRESHOLD
end

#hash160 ⇒ Object 



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# File 'lib/bitcoin/ext_key.rb', line 69

def hash160
  Bitcoin.hash160(pub)
end

#identifier ⇒ Object

get key identifier



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# File 'lib/bitcoin/ext_key.rb', line 79

def identifier
  Bitcoin.hash160(key.pubkey)
end

#key_type ⇒ Object

get key type defined by BIP-178 using version.



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# File 'lib/bitcoin/ext_key.rb', line 128

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 ⇒ Object

get private key(hex)



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# File 'lib/bitcoin/ext_key.rb', line 60

def priv
  key.priv_key
end

#priv_ver_to_pub_ver ⇒ Object

convert privkey version to pubkey version



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# File 'lib/bitcoin/ext_key.rb', line 188

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 ⇒ Object

get public key(hex)



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# File 'lib/bitcoin/ext_key.rb', line 65

def pub
  key.pubkey
end

#to_base58 ⇒ Object

Base58 encoded extended private key



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# File 'lib/bitcoin/ext_key.rb', line 55

def to_base58
  ExtPubkey.encode_base58(to_hex)
end

#to_payload ⇒ Object

serialize extended private key



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# File 'lib/bitcoin/ext_key.rb', line 49

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 ⇒ Object

get version bytes using serialization format



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# File 'lib/bitcoin/ext_key.rb', line 122

def version
  return ExtKey.version_from_purpose(number) if depth == 1
  ver ? ver : Bitcoin.chain_params.extended_privkey_version
end