Module: Bitcoin::Base58

Defined in:
lib/bitcoin/base58.rb

Overview

Base58Check encoding https://en.bitcoin.it/wiki/Base58Check_encoding

Constant Summary collapse

ALPHABET = 
'123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
SIZE = 
ALPHABET.size
MAX_LENGTH =

Upper bound for #decode. Decoding is quadratic in the length of the input, and the longest value Bitcoin encodes with Base58 is an extended key, at 111 characters.

256

Class Method Summary collapse

Class Method Details

.decode(base58_val) ⇒ String

decode base58 string to hex value. which is not in the alphabet.

Parameters:

  • base58_val (String) —

    Base58 string.

Returns:

  • (String) —

    Decoded value with hex format.

Raises:

  • (ArgumentError) —

    If base58_val is longer than MAX_LENGTH or holds a character



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# File 'lib/bitcoin/base58.rb', line 32

def decode(base58_val)
  if base58_val.length > MAX_LENGTH
    raise ArgumentError, "Base58 string must not be longer than #{MAX_LENGTH} characters."
  end
  int_val = 0
  base58_val.each_char do |char|
    char_index = ALPHABET.index(char)
    raise ArgumentError, 'Value passed not a valid Base58 String.' if char_index.nil?
    int_val = int_val * SIZE + char_index
  end
  s = int_val.to_even_length_hex
  s = '' if s == '00'
  leading_zero_bytes = (base58_val.match(/^([1]+)/) ? $1 : '').size
  s = ('00' * leading_zero_bytes) + s if leading_zero_bytes > 0
  s
end

.encode(hex) ⇒ Object

encode hex value to base58 string.



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# File 'lib/bitcoin/base58.rb', line 16

def encode(hex)
  leading_zero_bytes = (hex.match(/^([0]+)/) ? $1 : '').size / 2
  int_val = hex.to_i(16)
  base58_val = ''
  while int_val > 0
    int_val, remainder = int_val.divmod(SIZE)
    base58_val = ALPHABET[remainder] + base58_val
  end
  ('1' * leading_zero_bytes) + base58_val
end