How genereate pub key from priv key ? algo

Question

How to generate pub key from prive key ? All examples and explain skip this. but i dont need steps to address etc . i only need steps from priv to pub ( compressed or not ) what using at that. if possible example or python , or simple algo what used. example i hv priv key 981F3AF336E23EEFF4384A939065C4C623E394F1AE7E4D922C045CEDC3F258D2 i want make from them pub key , (i not need generation priv key i have them!) compressed or uncompressed . what steps i need to do for make valid public key for bitcoin address .

Update sorry for my qustion , i cannot undestand this logic. i try make pub key as example with 04 uncompresed from priv key 0x64hex, i not need steps for make it base58. i stuck at that step. as example i hv some words i make from them hex 0x64digits. how i can do from them not public key as example 049f35c793522be1fdcfd50c3fb15f455cda37fb3fb779b9e4707c89a49cdf47242c3dc34778f7361a44c074a6a21e5972bbf5ca5265c9ea121ce4f2a5dc4964b6

Answer 1

Private key used in the example: a84860187211d36cddfb77fc7638c996b8b8a77d3e16f2e47a5172fe6e8e2be6

Converting Private Key to WIF (Ruby)

require 'digest'

# Checksums use hash256 (where data is hashed twice through sha256)
def hash256(hex)
    binary = [hex].pack("H*")
    hash1 = Digest::SHA256.digest(binary)
    hash2 = Digest::SHA256.digest(hash1)
    result = hash2.unpack("H*")[0]
    return result
end

def checksum(hex)
  hash = hash256(hex) # Hash the data through SHA256 twice
  return hash[0...8]  # Return the first 4 bytes (8 characters)
end

def base58_encode(hex)
  @chars = %w[
      1 2 3 4 5 6 7 8 9
    A B C D E F G H   J K L M N   P Q R S T U V W X Y Z
    a b c d e f g h i j k   m n o p q r s t u v w x y z
]
  @base = @chars.length

  i = hex.to_i(16)
  buffer = String.new

  while i > 0
    remainder = i % @base
    i = i / @base
    buffer = @chars[remainder] + buffer
  end

  #! Is it just the 00, or does 05 get converted to 3, etc.
  # add '1's to the start based on number of leading bytes of zeros
  leading_zero_bytes = (hex.match(/^([0]+)/) ? $1 : '').size / 2

  ("1"*leading_zero_bytes) + buffer
end


# Convert Private Key to WIF
privatekey = "a84860187211d36cddfb77fc7638c996b8b8a77d3e16f2e47a5172fe6e8e2be6"
extended = "80" + privatekey + "01"
extendedchecksum = extended + checksum(extended)
wif = base58_encode(extendedchecksum)

puts wif

Get Public Key from WIF (Python)

from bitcoinutils.setup import setup
from bitcoinutils.keys import PrivateKey, PublicKey

def main():
    # setup the network
    setup('mainnet')

    # existing WIF key
    priv = PrivateKey.from_wif('L2rq82XD1P9bwnyithBaRYn7v91WxRCSraTrfbu6g86VLYsnCmbt')


    # get the public key
    pub = priv.get_public_key()

    # compressed public key
    print("Public key:", pub.to_hex(compressed=True))

if __name__ == "__main__":
      main()

Source:

https://github.com/in3rsha/learnmeabitcoin-code/blob/master/keygenerator.rb

https://github.com/karask/python-bitcoin-utils/blob/master/examples/keys_addresses.py