Convert Dash BIP32 extended public key version prefix from 'xpub' to 'drkv'

conv.rb

#! /usr/bin/env ruby

# Utility converting BIP32 extended key version bytes

require './dashutil'

xkey = ARGV.shift
pref = ARGV.shift

# xpub661MyMwAqRbcFnEEbFf8idiyo8QGKiqhTujUmaJsDhAEZ82cEQPMq69Y4V27vGc5rJnxsd26kyHpBJDW72YMjntsmASbdBy1awfGMsUvLCa
puts DashUtil.swap_prefix(xkey, pref)

convert-xpub-to-drkv.rb

#! /usr/bin/env ruby

# Example of converting Dash BIP32 extended public key (incorrectly) beginning
# with 'xpub' to correct prefix 'drkv'.
#

require 'bitcoin'

# test extended pub key
xpub = 'xpub661MyMwAqRbcF3jZGiw3QBt7nD13a7k8jVt9me27BL1vSeSpviDj6udJ5cnFyr2q2ofw7kMKGUepVhVsbLVsckxGzDmvnpGPr88CJAz1Ab5'

# Dash extended public key prefix
drkv_prefix = '02fe52f8'

# decode base58 pubkey
bin = Bitcoin.decode_base58(xpub)

# replace 4-byte version prefix
bin[0..7] = drkv_prefix
version            = bin[0..7]    # 0488b21e
depth              = bin[8..9]    # 00
parent_fingerprint = bin[10..17]  # 00000000
child              = bin[18..25]  # 00000000
chain_code         = bin[26..89]  # 32bdad605aae059ae99303a1b74c8492630a0bf9f3b45680dfe82b03f8174365
key_data           = bin[90..155] # 03906d7e79f8b55ce4d7720bbd478dff3f11f832459d2890e2c8fb2b3316e18455

# checksum...
# b43167ec


puts "version: #{version}"
puts "depth: #{depth}"
puts "parent_fingerprint: #{parent_fingerprint}"
puts "child: #{child}"
puts "chain_code: #{chain_code}"
puts "key_data: #{key_data}"

# add the checksum to the 78-byte xkey
drkbin = bin[0..155] + Bitcoin.checksum(bin[0..155])

# base58 encode again
drk = Bitcoin.encode_base58(drkbin)

# result has proper 'drkv' prefix and generates same addresses
puts drk
# => drkvjJe5sJgqomjLnD39LKGdme64zzL4d38fDEhkveYsjvqDZzEZSoq6VEE5znetSRvSB6pYAxhTViXJdZ5QygKogD4nsa31hQ8aVuW6psczteC

dashutil.rb

# Dash BIP32 utilities

require 'bitcoin'
require 'byebug'
require 'pp'

class DashUtil
  VERSION_BYTES = {
    'drkv' => '02fe52f8',
    'drkp' => '02fe52cc',
    'DRKV' => '3a8061a0',
    'DRKP' => '3a805837',
    'xpub' => '0488b21e',
    'xprv' => '0488ade4',
    'tpub' => '043587cf',
    'tprv' => '04358394',
  }

  def self.swap_version_bytes(xkey, version_bytes)
    hex = Bitcoin.decode_base58(xkey)
    hex[0..7] = version_bytes
    hex = hex[0..155] + Bitcoin.checksum(hex[0..155])
    new_xkey = Bitcoin.encode_base58(hex)
    return new_xkey
  end

  def self.swap_prefix(xkey, prefix)
    swap_version_bytes(xkey, VERSION_BYTES[prefix])
  rescue StandardError => ex
    throw ex
  end
end

gen-electrum-pubkeys.rb

#! /usr/bin/env ruby

# Utility converting BIP32 extended key version bytes

require 'dashruby'
require 'dashruby/extensions'
require './dashutil'

def gen_electrum_public_keys(xkey, type = :receive, num = 10)
  path_prefix = (:change == type) ? "1" : "0"

  # TODO: validation, also parsing pub/priv, etc.
  if !xkey.match(/^drk[pv]/)
    # TODO: determine prefix based on pub/priv key data (not version bytes)

    # this assumes public key, which is a bad assumption.
    xkey = DashUtil.swap_prefix(xkey, 'drkv')
  end

  public_keys = []
  kc = Dash::Keychain.new(extended_key: xkey)
  (0..(num-1)).each do |n|
    path = "#{path_prefix}/#{n}"
    pubkey = kc.derived_key(path).public_key.to_hex
    public_keys.push( pubkey )
  end

  return public_keys
end

xkey = ARGV.shift
type = ARGV.shift || 'receive'
num  = ARGV.shift || '5'

type = type.to_sym
num  = num.to_i   || 5

print "\n\n"
gen_electrum_public_keys(xkey, type, num).each do |pubkey|
  puts pubkey
end

notes.txt

# original incorrect 'xpub' key:
xpub661MyMwAqRbcF3jZGiw3QBt7nD13a7k8jVt9me27BL1vSeSpviDj6udJ5cnFyr2q2ofw7kMKGUepVhVsbLVsckxGzDmvnpGPr88CJAz1Ab5

# First two receiving addresses generated by Electrum:
XfodG6PGyXksxznJXzKFPgU1q9QdPBNYB2
Xb4AKDUJBkjUSYVzuMXxLAxkUJaWomozGT

# ----------------------------------------------------------------------

# correctly convert 'drkv' key:
drkvjJe5sJgqomjLnD39LKGdme64zzL4d38fDEhkveYsjvqDZzEZSoq6VEE5znetSRvSB6pYAxhTViXJdZ5QygKogD4nsa31hQ8aVuW6psczteC

# First two receiving addresses generated by Electrum:
XfodG6PGyXksxznJXzKFPgU1q9QdPBNYB2
Xb4AKDUJBkjUSYVzuMXxLAxkUJaWomozGT

test.rb

#! /usr/bin/env ruby

require 'dashruby'
require 'dashruby/extensions'

# test extended pub key
xkey = 'drkvjJe5sJgqomjLnwXpeqzj65vw1ujHNeEDweZ5vaqdnHyXgTpLkVzjDQkKyetkNrVgzbwZvqNEzDAJK9o3VNNHoF1PeWhgXmqCEj3AtcMrX1c'

path = '0/0'
kc = Dash::Keychain.new(extended_key: xkey)
derived = kc.derived_key(path)
pubkey = derived.public_key.to_hex
addr = derived.address.to_s

puts "      Path: m/#{path}"
puts "Public Key: #{pubkey}"
puts "   Address: #{addr}"
print "\n"