Module: Base58Block

Defined in:
lib/base58block.rb

Constant Summary collapse

DICTIONARY = 
"123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
REVERSE = 
[
 0,   1,   2,   3,   4,   5,   6,   7,   8, nil, nil, nil, nil, 
    nil, nil, nil,   9,  10,  11,  12,  13,  14,  15,  16, nil,  17, 
18,  19,  20,  21, nil,  22,  23,  24,  25,  26,  27,  28,  29,
30,  31,  32, nil, nil, nil, nil, nil, nil,  33,  34,  35,  36,
37,  38,  39,  40,  41,  42,  43, nil,  44,  45,  46,  47,  48,
49,  50,  51,  52,  53,  54,  55,  56,  57 ]
REVERSE_START = 
49

Class Method Summary collapse

Class Method Details

.decode(text) ⇒ Object 



61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
 
# File 'lib/base58block.rb', line 61

def self.decode text
  text = text.dup
  result = "".force_encoding "binary"

  # operate on blocks of 8 bytes. The last block may less than 8 bytes
  text.each_char.each_slice(11) do |block|
    
    # create an array of the individual base 58 'digits'
    decoded_block = block.map{|c| reverse_dictionary c }
    if decoded_block.include? nil
      return nil
    end

    # decode the byte count, stripping off the flag if needed
    byte_count = 8
    if decoded_block[0] >= 43
      byte_count = c[0] - 43
      decoded_block = decoded_block[1..-1]
    end

    # convert to integer value
    integer = decoded_block.inject{|sum, i| sum * 58 + i }

    # convert integer to 8 byte array (in reverse order)
    data = []
    8.times do
      integer, mod = integer.divmod 256
      data << mod
    end
    # strip off the leading zero bytes if we are a different byte count
    data = data[0...byte_count].reverse

    # pack bytes to a (binary) string and append to result
    result << data.pack("C*")
  end
  result
end

.encode(data) ⇒ Object 



25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
 
# File 'lib/base58block.rb', line 25

def self.encode data
  data = data.dup
  result = ""
  
  # operate on blocks of 8 bytes. The last block may less than 8 bytes
  data.each_byte.each_slice(8) do |block|
    encoded_block = ""
    count = block.length

    #convert input block into an integer using network order
    total = block.inject {|sum, n| sum * 256 + n }

    # repeatedly mod/divide 
    while total > 0 do
      total, index = total.divmod 58
      encoded_block << DICTIONARY[index]
    end

    # if output is less than 11 characters, pad with "1"
    padding = 11 - encoded_block.bytesize
    encoded_block << "1" * padding
    
    # indicate less than eight bytes by changing the high order character
    # (which is always '1' if you have less than eight bytes input) to
    # a value which cannot occur
    if count < 8
      encoded_block[10] = DICTIONARY[43+count]
    end
    
    # We want the data to be in network order, so we reverse it now
    encoded_block = encoded_block.reverse
    result << encoded_block
  end
  result
end