How to generate Bitcoin address in Ruby

Question

I'm trying to generate Bitcoin addresses in ruby.

Here's the class I'm using:

require 'openssl'

require 'ecdsa'

require 'securerandom'

require 'base58'


class BitcoinAddressGenerator


  ADDRESS_VERSION = '00'


  def self.generate_address

    # Bitcoin uses the secp256k1 curve

    curve = OpenSSL::PKey::EC.new('secp256k1')


    # Now we generate the public and private key together

    curve.generate_key


    private_key_hex = curve.private_key.to_s(16)

    puts "private_key_hex: #{private_key_hex}"

    public_key_hex = curve.public_key.to_bn.to_s(16)

    puts "public_key_hex: #{public_key_hex}"


    pub_key_hash = public_key_hash(public_key_hex)

    puts "pub_key_hash: #{pub_key_hash}"


    address = generate_address_from_public_key_hash(public_key_hash(public_key_hex))


    puts "address: #{address}"

  end


  def self.generate_address_from_public_key_hash(pub_key_hash)

    pk = ADDRESS_VERSION + pub_key_hash

    encode_base58(pub_key_hash + checksum(pub_key_hash))

  end


  def self.int_to_base58(int_val, leading_zero_bytes=0)

    alpha = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

    base58_val, base = '', alpha.size

    while int_val > 0

      int_val, remainder = int_val.divmod(base)

      base58_val = alpha[remainder] + base58_val

    end

    base58_val

  end


  def self.encode_base58(hex)

    leading_zero_bytes = (hex.match(/^([0]+)/) ? $1 : '').size / 2

    ("1"*leading_zero_bytes) + int_to_base58( hex.to_i(16) )

  end


  def self.checksum(hex)

    sha256(sha256(hex))[0...8]

  end


  # RIPEMD-160 (160 bit) hash

  def self.rmd160(hex)

    Digest::RMD160.hexdigest([hex].pack("H*"))

  end


  def self.sha256(hex)

   Digest::SHA256.hexdigest([hex].pack("H*"))

  end


  # Turns public key into the 160 bit public key hash

  def self.public_key_hash(hex)

    rmd160(sha256(hex))

  end


end

It returns an invalid address.

Any suggestions?

Answer 1

In your generate_address_from_public_key_hash method, the checksum should be over the hash including the address prefix. You’re not actually using the pk variable at all at the moment after you assign it. The code should look something like:

def self.generate_address_from_public_key_hash(pub_key_hash)

  pk = ADDRESS_VERSION + pub_key_hash

  encode_base58(pk + checksum(pk)) # Using pk here, not pub_key_hash

end