Module: Nano::Base32

Extended by:
Base32
Included in:
Base32
Defined in:
lib/nano/base32.rb

Overview

This module performs encoding and decoding of Base32 as specified by the Nano protocol.

Constant Summary collapse

ALPHABET =

The Base32 alphabet of characters.

"13456789abcdefghijkmnopqrstuwxyz".freeze

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.read_char(chr) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/nano/base32.rb', line 79

def read_char(chr)
  idx = ALPHABET.index(chr)
  raise ArgumentError, "Character #{chr} not base32 compliant" if idx.nil? 
  idx
end

Instance Method Details

#decode(str) ⇒ Object

Decodes a Base32 encoded string into a hex string

Parameters:

  • str (String) —

    The base32 encoded string



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# File 'lib/nano/base32.rb', line 51

def decode(str)
  length = str.length
  leftover = (length * 5) % 8
  offset = leftover == 0 ? 0 : 8 - leftover

  bits = 0
  value = 0

  output = Array.new

  length.times do |i|
    value = (value << 5) | read_char(str[i])
    bits += 5

    if bits >= 8
      output.push((value >> (bits + offset - 8)) & 255)
      bits -= 8
    end
  end

  if bits > 0
    output.push((value << (bits + offset - 8)) & 255)
  end

  output = output.drop(1) unless leftover == 0
  Nano::Utils.bytes_to_hex(output)
end

#encode(bytes) ⇒ String

Encode an array of bytes into Base32 string.

Parameters:

  • bytes (Array<Int8>) —

    The byte array to encode.

Returns:

  • (String) —

    The base32 encoded representation of the bytes



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# File 'lib/nano/base32.rb', line 20

def encode(bytes)
  length = bytes.length
  leftover = (length * 8) % 5
  offset = leftover == 0 ? 0 : 5 - leftover
  value = 0
  output = ""
  bits = 0

  length.times do |i|
    value = (value << 8) | bytes[i]
    bits += 8

    while bits >= 5
      output += ALPHABET[(value >> bits + offset - 5) & 31]
      bits -= 5
    end
  end

  if bits > 0
    output += ALPHABET[(value << (5 - (bits + offset))) & 31]
  end

  output
end