Class: Bitcoin::ExtKey

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

Overview

BIP32 Extended private key

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#chain_code ⇒ Object

Returns the value of attribute chain_code.



14
15
16
 
# File 'lib/bitcoin/ext_key.rb', line 14

def chain_code
  @chain_code
end

#depth ⇒ Object

Returns the value of attribute depth.



12
13
14
 
# File 'lib/bitcoin/ext_key.rb', line 12

def depth
  @depth
end

#key ⇒ Object

Bitcoin::Key



15
16
17
 
# File 'lib/bitcoin/ext_key.rb', line 15

def key
  @key
end

#number ⇒ Object

Returns the value of attribute number.



13
14
15
 
# File 'lib/bitcoin/ext_key.rb', line 13

def number
  @number
end

#parent_fingerprint ⇒ Object

Returns the value of attribute parent_fingerprint.



16
17
18
 
# File 'lib/bitcoin/ext_key.rb', line 16

def parent_fingerprint
  @parent_fingerprint
end

#ver ⇒ Object

Returns the value of attribute ver.



11
12
13
 
# File 'lib/bitcoin/ext_key.rb', line 11

def ver
  @ver
end

Class Method Details

.from_base58(address) ⇒ Object

import private key from Base58 private key address



152
153
154
 
# File 'lib/bitcoin/ext_key.rb', line 152

def self.from_base58(address)
  ExtKey.parse_from_payload(Base58.decode(address).htb)
end

.generate_master(seed) ⇒ Object

generate master key from seed.



20
21
22
23
24
25
26
27
28
29
30
 
# File 'lib/bitcoin/ext_key.rb', line 20

def self.generate_master(seed)
  ext_key = ExtKey.new
  ext_key.depth = ext_key.number = 0
  ext_key.parent_fingerprint = '00000000'
  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) ⇒ Object 



137
138
139
140
141
142
143
144
145
146
147
148
149
 
# File 'lib/bitcoin/ext_key.rb', line 137

def self.parse_from_payload(payload)
  buf = StringIO.new(payload)
  ext_key = ExtKey.new
  ext_key.ver = buf.read(4).bth # version
  raise 'An unsupported version byte was specified.' unless ExtKey.support_version?(ext_key.ver)
  ext_key.depth = buf.read(1).unpack('C').first
  ext_key.parent_fingerprint = buf.read(4).bth
  ext_key.number = buf.read(4).unpack('N').first
  ext_key.chain_code = buf.read(32)
  buf.read(1) # 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) 


170
171
172
173
 
# File 'lib/bitcoin/ext_key.rb', line 170

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.



157
158
159
160
161
162
163
164
165
166
167
 
# File 'lib/bitcoin/ext_key.rb', line 157

def self.version_from_purpose(purpose)
  v = purpose - 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

#addr ⇒ Object

get address



72
73
74
 
# File 'lib/bitcoin/ext_key.rb', line 72

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:



95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
 
# File 'lib/bitcoin/ext_key.rb', line 95

def derive(number, harden = false)
  number += HARDENED_THRESHOLD if harden
  new_key = ExtKey.new
  new_key.depth = depth + 1
  new_key.number = number
  new_key.parent_fingerprint = fingerprint
  if number > (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 ⇒ Object

get ExtPubkey from priv_key



33
34
35
36
37
38
39
40
41
42
 
# File 'lib/bitcoin/ext_key.rb', line 33

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



82
83
84
 
# File 'lib/bitcoin/ext_key.rb', line 82

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

#hardened? ⇒ Boolean

whether hardened key.

Returns:

  • (Boolean) 


87
88
89
 
# File 'lib/bitcoin/ext_key.rb', line 87

def hardened?
  number >= HARDENED_THRESHOLD
end

#hash160 ⇒ Object 



67
68
69
 
# File 'lib/bitcoin/ext_key.rb', line 67

def hash160
  Bitcoin.hash160(pub)
end

#identifier ⇒ Object

get key identifier



77
78
79
 
# File 'lib/bitcoin/ext_key.rb', line 77

def identifier
  Bitcoin.hash160(key.pubkey)
end

#key_type ⇒ Object

get key type defined by BIP-178 using version.



125
126
127
128
129
130
131
132
133
134
135
 
# File 'lib/bitcoin/ext_key.rb', line 125

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)



58
59
60
 
# File 'lib/bitcoin/ext_key.rb', line 58

def priv
  key.priv_key
end

#priv_ver_to_pub_ver ⇒ Object

convert privkey version to pubkey version



176
177
178
179
180
181
182
183
184
185
 
# File 'lib/bitcoin/ext_key.rb', line 176

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)



63
64
65
 
# File 'lib/bitcoin/ext_key.rb', line 63

def pub
  key.pubkey
end

#to_base58 ⇒ Object

Base58 encoded extended private key



51
52
53
54
55
 
# File 'lib/bitcoin/ext_key.rb', line 51

def to_base58
  h = to_payload.bth
  hex = h + Bitcoin.calc_checksum(h)
  Base58.encode(hex)
end

#to_payload ⇒ Object

serialize extended private key



45
46
47
48
 
# File 'lib/bitcoin/ext_key.rb', line 45

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



119
120
121
122
 
# File 'lib/bitcoin/ext_key.rb', line 119

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