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

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

# add the checksum to the 78-byte xpub key
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

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