Class: Base58::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/base58-alphabets/base.rb

Direct Known Subclasses

Bitcoin, Flickr

Constant Summary collapse

BASE =

ALPHABET.length == 58 ## 58 chars/letters/digits

58
HEX_RE =

check if it is a hex (string)

- allow optiona 0x or 0X  and allow abcdef and ABCDEF

/\A(?:0x)?[0-9a-f]+\z/i

Class Method Summary collapse

Class Method Details

._bytes(num, base: BASE) ⇒ Object

(private) helper - note: leading underscore in name e.g. _bytes



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# File 'lib/base58-alphabets/base.rb', line 92

def self._bytes( num, base: BASE )   ## num_to_bytes

  ## note: 0 leads to empty []  and NOT [0] !!!!

  b = []
  while num > 0
    num, mod = num.divmod( base )
    b << mod
  end
  b = b.reverse
  b
end

._pack(bytes) ⇒ Object

bytes_to_num



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# File 'lib/base58-alphabets/base.rb', line 104

def self._pack( bytes )   ## bytes_to_num

  num = 0
  bytes.reverse.each_with_index do |byte,index|
    num += byte * (BASE**(index))
  end
  num
end

._strip0x(str) ⇒ Object

todo/check: add alias e.g. strip_hex_prefix or such - why? why not?



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# File 'lib/base58-alphabets/base.rb', line 113

def self._strip0x( str )    ## todo/check: add alias e.g. strip_hex_prefix or such - why? why not?

  (str[0,2] == '0x' || str[0,2] == '0X') ?  str[2..-1] : str
end

.decode_bin(str) ⇒ Object 



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# File 'lib/base58-alphabets/base.rb', line 69

def self.decode_bin( str )
  num = decode_num( str )

  ## use base 256 for characters to binary conversion!!!

  data = _bytes( num, base: 256 ).pack( 'C*' )

  ## check for leading zeros

  str.bytes.each do |byte|
    break if byte != alphabet[0].ord
    data = "\x00" + data
  end
  data
end

.decode_hex(str) ⇒ Object 



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# File 'lib/base58-alphabets/base.rb', line 83

def self.decode_hex( str )
  decode_bin( str ).unpack( 'H*' )[0]
end

.decode_num(str) ⇒ Object

Converts a base58 string to a base10 integer.



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# File 'lib/base58-alphabets/base.rb', line 58

def self.decode_num( str )     ## todo/check: add alias base58_to_num / base58_to_int

  bytes = str.each_char.reduce([]) do |bytes,char|
               byte = number[char]
               raise ArgumentError, "Value passed not a valid base58 string - >#{char}< not found in alphabet"  if byte.nil?
               bytes << byte
               bytes
          end
  _pack( bytes )
end

.encode_bin(data) ⇒ Object

Converts binary string into its Base58 representation. If string is empty returns an empty string.



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# File 'lib/base58-alphabets/base.rb', line 27

def self.encode_bin( data )   ## todo/check: add alias such as bin_to_base58 / data_to_base58 - why? why not?

  leading_zeroes = 0
  num = 0
  base = 1
  data.bytes.reverse_each do |byte|
      if byte == 0
        leading_zeroes += 1
      else
        leading_zeroes = 0
        num += base*byte
      end
      base *= 256
  end

  (alphabet[0]*leading_zeroes) + encode_num( num )
end

.encode_hex(str) ⇒ Object

Converts hex string into its Base58 representation.

Raises:

  • (ArgumentError) 


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# File 'lib/base58-alphabets/base.rb', line 46

def self.encode_hex( str )
  ## todo/check: allow empty string ("") - why? why not?

  raise ArgumentError, "expected hex string (0-9a-f) - got >#{str}< - can't pack string; sorry"   unless str =~ HEX_RE || str.empty?

  str = _strip0x( str )  ##  check if input starts with 0x or 0X if yes - (auto-)cut off!!!!!

  encode_bin( [str].pack('H*') )
end

.encode_num(num) ⇒ Object

Converts a base10 integer to a base58 string.



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# File 'lib/base58-alphabets/base.rb', line 17

def self.encode_num( num )   ## num_to_base58 / int_to_base58

  _bytes( num ).reduce( String.new ) do |buf, byte|
    buf << alphabet[byte]
    buf
  end
end