Module: OpenLoam::Base32

Defined in:
lib/open_loam/base32.rb

Overview

RFC 4648 Base32 — the encoding authenticator apps expect for a TOTP secret. Ruby ships Base64 but not Base32, and this is ~15 lines, so no dependency. No padding on encode (authenticators don't want it); decode ignores case, spaces and = padding so a secret pasted from anywhere still works.

Constant Summary collapse

ALPHABET = 
"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567".freeze

Class Method Summary collapse

Class Method Details

.decode(string) ⇒ Object 



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# File 'lib/open_loam/base32.rb', line 16

def self.decode(string)
  clean = string.to_s.upcase.gsub(/[^A-Z2-7]/, "")
  bits = clean.each_char.map { |char| ALPHABET.index(char).to_s(2).rjust(5, "0") }.join
  # Only whole bytes are data; the trailing <8 bits are encoding padding.
  bits.scan(/.{8}/).map { |byte| byte.to_i(2).chr }.join.b
end

.encode(bytes) ⇒ Object 



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# File 'lib/open_loam/base32.rb', line 9

def self.encode(bytes)
  bits = bytes.bytes.map { |byte| byte.to_s(2).rjust(8, "0") }.join
  # Pad the bit string up to a multiple of 5, then map each 5 bits to a char.
  bits += "0" * ((5 - bits.length % 5) % 5)
  bits.scan(/.{5}/).map { |chunk| ALPHABET[chunk.to_i(2)] }.join
end