WIF Private Key

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# ---------
# Functions
# ---------

require 'digest'

# hash256 function (checksums use hash256)
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

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

# base58 encode function
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

  # 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

# ----------
# WIF Encode
# ----------

# 1. start with a 32-byte hexadecimal private key
privatekey = "ef235aacf90d9f4aadd8c92e4b2562e1d9eb97f0df9ba3b508258739cb013db2" # example, do not use

# 2. add prefix (80 = mainet, ef = testnet)
data = "80" + privatekey

# 3. add compression byte (optional)
data = data + "01"

# 4. add checksum
data = data + checksum(data)

# 5. base58 encode
wif = base58_encode(data)

# result
puts wif #=> L5EZftvrYaSudiozVRzTqLcHLNDoVn7H5HSfM9BAN6tMJX8oTWz6

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import hashlib # SHA-256 hash function

# 1. start with a 32-byte hexadecimal private key
privatekey = "ef235aacf90d9f4aadd8c92e4b2562e1d9eb97f0df9ba3b508258739cb013db2" # example, do not use

# 2. add prefix (80 = mainet, ef = testnet)
data = "80" + privatekey

# 3. add compression byte (optional)
data = data + "01"

# 4. add checksum (hash256 the prefix+data+checksum, then take the first 4 bytes)
hash1 = hashlib.sha256(bytes.fromhex(data)).digest() # convert hex string to raw bytes before hashing
hash2 = hashlib.sha256(hash1).hexdigest() # return result as hex string
checksum = hash2[0:8] # checksum is the first 4 bytes
data = data + checksum # add checksum to the end of the data

# 5. set base58 characters
characters = ['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']

# 6. convert hex data to integer so we can convert it to base58
i = int(data, 16)

# 7. create a buffer for holding the base58 string
base58 = ''

# 8. keep dividing the integer by 58 and taking the remainder to work out each base58 character
while i > 0:
  i, remainder = divmod(i, 58) # divide and get the remainder
  base58 = characters[remainder] + base58 # use the remainder to get the character, and add it to the start of the string

# note: during normal base58 encoding you convert leading 00 bytes in hex to 1s in base58, but leading zero bytes will not be present when creating a wif private key so we're skipping that step here

# 9. show result (wif private key)
print(base58) #=> L5EZftvrYaSudiozVRzTqLcHLNDoVn7H5HSfM9BAN6tMJX8oTWz6

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# ---------
# Functions
# ---------

# base58 decode function
def base58_decode(base58_string)

  # base58 characters
  base58_chars = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

  # set starting integer value
  integer = 0

  # run through each character in the string from right to left
  base58_string.reverse.each_char.with_index do |char, index|
  
    # get the position of the character in the list of base58 characters
    char_index = base58_chars.index(char)
    
    # check its a valid base58 character
    if !char_index
     puts "Not a valid Base58 character: #{char}"
     exit
    end
    
    # multiply the position of the character by a power of 58 (increasing for the index of each character)
    integer += char_index * (58**index)
  end
  
  # convert the integer to a hexadecimal string
  hexadecimal = integer.to_s(16)
  
  # pad out to make sure it's an even number of bytes
  if hexadecimal.bytesize.odd?
    hexdecimal = "0" + hexadecimal
  end
  
  # ignore empty base58 strings
  if hexadecimal == "00"
    hexadecimal = ""
  end
  
  # count the number of leading 1's
  leading_zero_bytes = (base58_string.match(/^([1]+)/) ? $1 : '').size
  
  # convert leading 1's to leading 00's
  if leading_zero_bytes > 0
    hexadecimal = ("00" * leading_zero_bytes) + hexadecimal
  end
  
  # return hexadecimal bytes
  return hexadecimal
end

# ----------
# WIF Decode
# ----------

# 1. start with a wif private key
wif = "L5EZftvrYaSudiozVRzTqLcHLNDoVn7H5HSfM9BAN6tMJX8oTWz6" # example, do not use

# 2. base58 decode
data = base58_decode(wif)

# 3. extract the private key (bytes 1 to 33)
privatekey = data[2...66]

# result
puts privatekey #=> ef235aacf90d9f4aadd8c92e4b2562e1d9eb97f0df9ba3b508258739cb013db2

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# 1. start with a wif private key
wif = "L5EZftvrYaSudiozVRzTqLcHLNDoVn7H5HSfM9BAN6tMJX8oTWz6" # example, do not use

# 2. set base58 characters
characters = ['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']

# 3. convert base58 string to integer

# 3a. reverse the base58 string so we can work from right to left
wif = wif[::-1]

# 3b. set starting value
sum = 0

# 3c. run through each character in the wif private key (the base58 string)
for i, c in enumerate(wif):

  # 3d. get the index number of this character from the list of base58 characters
  for index, base58_character in enumerate(characters): # this is a basic way to find the key from the list, but it works
    if (c == base58_character):
      character_index = index
      break # stop looking

  # 3e. multiply the index of the character by a power of 58 (increasing the power based on the position of the character in the base58 string), then add this to the sum
  sum += character_index * (58**i)

# 4. convert integer to a hexadecimal
hexadecimal = hex(sum)[2:] # remove the 0x prefix using [2:]

# note: during normal base58 decoding you convert leading 1s in base58 to leading 00 bytes in hex, but wif private keys never start with a 1 so we're skipping that step here

# 5. extract the private key (ignore the prefix, compression byte, and checksum)
privatekey = hexadecimal[2:66]

# 6. pad out the private key so it always shows as 32 bytes (64 hexadecimal characters)
privatekey = privatekey.zfill(64) # zfill pads with zeros at the start to the desired length

# 6. show result
print(privatekey) #=> ef235aacf90d9f4aadd8c92e4b2562e1d9eb97f0df9ba3b508258739cb013db2