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module ROTP
class Base32
class Base32Error < RuntimeError; end
CHARS = "abcdefghijklmnopqrstuvwxyz234567".each_char.to_a
class << self
def decode(str)
output = []
str.scan(/.{1,8}/).each do |block|
char_array = decode_block(block).map{|c| c.chr}
output << char_array
end
output.join
end
def random_base32(length=16)
b32 = ''
OpenSSL::Random.random_bytes(length).each_byte do |b|
b32 << CHARS[b % 32]
end
b32
end
private
def decode_block(block)
length = block.scan(/[^=]/).length
quints = block.each_char.map {|c| decode_quint(c)}
bytes = []
bytes[0] = (quints[0] << 3) + (quints[1] ? quints[1] >> 2 : 0)
return bytes if length < 3
bytes[1] = ((quints[1] & 3) << 6) + (quints[2] << 1) + (quints[3] ? quints[3] >> 4 : 0)
return bytes if length < 4
bytes[2] = ((quints[3] & 15) << 4) + (quints[4] ? quints[4] >> 1 : 0)
return bytes if length < 6
bytes[3] = ((quints[4] & 1) << 7) + (quints[5] << 2) + (quints[6] ? quints[6] >> 3 : 0)
return bytes if length < 7
bytes[4] = ((quints[6] & 7) << 5) + (quints[7] || 0)
bytes
end
def decode_quint(q)
CHARS.index(q.downcase) or raise(Base32Error, "Invalid Base32 Character - '#{q}'")
end
end
end
end
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