Module: TOTP

Defined in:
lib/totp.rb

Class Method Summary collapse

Class Method Details

.passwords(secret, time = Time.now) ⇒ Object

Generate passwords based on the secret and time



34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
 
# File 'lib/totp.rb', line 34

def self.passwords(secret, time = Time.now)

  interval = time.to_i / 30

  hmac = OpenSSL::HMAC.new(
    Base32.decode(secret),
    OpenSSL::Digest::SHA1.new,
  )

  # Cover three 30 second intervals
  return [
    totp(hmac, interval.pred),
    totp(hmac, interval),
    totp(hmac, interval.succ),
  ]
end

.secret ⇒ Object

Generate a random secret



7
8
9
 
# File 'lib/totp.rb', line 7

def self.secret
  return Base32.encode((0...10).map { rand(255).chr }.join)
end

.totp(hmac, time) ⇒ Object 



16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
 
# File 'lib/totp.rb', line 16

def self.totp(hmac, time)
  bytes = [time].pack('>q').reverse

  hmac.reset
  hmac.update(bytes)

  code = hmac.digest
  offs = code[-1].ord & 0x0F
  hash = code[offs...offs + 4]

  pass = hash.reverse.unpack('L')[0]
  pass &= 0x7FFFFFFF
  pass %= 1000000

  return pass
end

.valid?(secret, pass, time = Time.now) ⇒ Boolean

Return whether or not the key is valid for the given secret

Returns:

  • (Boolean) 


12
13
14
 
# File 'lib/totp.rb', line 12

def self.valid?(secret, pass, time = Time.now)
  return self.passwords(secret, time).include?(pass)
end