Module: Bech32

Defined in:
lib/bech32.rb,
lib/bech32/version.rb,
lib/bech32/segwit_addr.rb

Defined Under Namespace

Modules: Encoding Classes: SegwitAddr

Constant Summary collapse

SEPARATOR = 
'1'
CHARSET = 
%w(q p z r y 9 x 8 g f 2 t v d w 0 s 3 j n 5 4 k h c e 6 m u a 7 l)
BECH32M_CONST = 
0x2bc830a3
VERSION = 
'1.3.0'

Class Method Summary collapse

Class Method Details

.convert_bits(data, from, to, padding = true) ⇒ Array

Convert a data where each byte is encoding from bits to a byte slice where each byte is encoding to bits.

Parameters:

  • data (Array)
  • from (Integer)
  • to (Integer)
  • padding (Boolean) (defaults to: true)

Returns:

  • (Array) 


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# File 'lib/bech32.rb', line 95

def convert_bits(data, from, to, padding=true)
  acc = 0
  bits = 0
  ret = []
  maxv = (1 << to) - 1
  max_acc = (1 << (from + to - 1)) - 1
  data.each do |v|
    return nil if v < 0 || (v >> from) != 0
    acc = ((acc << from) | v) & max_acc
    bits += from
    while bits >= to
      bits -= to
      ret << ((acc >> bits) & maxv)
    end
  end
  if padding
    ret << ((acc << (to - bits)) & maxv) unless bits == 0
  elsif bits >= from || ((acc << (to - bits)) & maxv) != 0
    return nil
  end
  ret
end

.create_checksum(hrp, data, spec) ⇒ Object

Returns computed checksum values of hrp and data



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# File 'lib/bech32.rb', line 63

def create_checksum(hrp, data, spec)
  values = expand_hrp(hrp) + data
  const = (spec == Bech32::Encoding::BECH32M ? Bech32::BECH32M_CONST : 1)
  polymod = polymod(values + [0, 0, 0, 0, 0, 0]) ^ const
  (0..5).map{|i|(polymod >> 5 * (5 - i)) & 31}
end

.decode(bech, max_length = 90) ⇒ Object

Returns the Bech32 decoded hrp and data.

require 'bech32'

addr = 'BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4'
hrp, data, spec = Bech32.decode(addr)

<i>Generates:</i>
'bc' # hrp
[0, 14, 20, 15, 7, 13, 26, 0, 25, 18, 6, 11, 13, 8, 21, 4, 20, 3, 17, 2, 29, 3, 12, 29, 3, 4, 15, 24, 20, 6, 14, 30, 22] # data
1 # spec see Bech32::Encoding



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# File 'lib/bech32.rb', line 44

def decode(bech, max_length = 90)
  # check uppercase/lowercase
  return nil if bech.bytes.index{|x| x < 33 || x > 126}
  return nil if (bech.downcase != bech && bech.upcase != bech)
  bech = bech.downcase
  # check data length
  pos = bech.rindex(SEPARATOR)
  return nil if pos.nil? || pos + 7 > bech.length || bech.length > max_length
  # check valid charset
  bech[pos+1..-1].each_char{|c|return nil unless CHARSET.include?(c)}
  # split hrp and data
  hrp = bech[0..pos-1]
  data = bech[pos+1..-1].each_char.map{|c|CHARSET.index(c)}
  # check checksum
  spec = verify_checksum(hrp, data)
  spec ? [hrp, data[0..-7], spec] : nil
end

.encode(hrp, data, spec) ⇒ Object

Returns the encoded Bech32 string.

require 'bech32'

bech = Bech32.encode('bc', [], Bech32::Encoding::BECH32)

<i>Generates:</i>
'BC1QW508D6QEJXTDG4Y5R3ZARVARY0C5XW7KV8F3T4' # bech



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# File 'lib/bech32.rb', line 27

def encode(hrp, data, spec)
  checksummed = data + create_checksum(hrp, data, spec)
  hrp + SEPARATOR + checksummed.map{|i|CHARSET[i]}.join
end

.verify_checksum(hrp, data) ⇒ Integer

Verify a checksum given Bech32 string

Parameters:

  • hrp (String) —

    hrp part.

  • data (Array[Integer]) —

    data array.

Returns:

  • (Integer) —

    spec



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# File 'lib/bech32.rb', line 74

def verify_checksum(hrp, data)
  const = polymod(expand_hrp(hrp) + data)
  case const
  when 1
    Encoding::BECH32
  when BECH32M_CONST
    Encoding::BECH32M
  end
end