Class: ROTP::OTP

Inherits:

Object

• Object
• ROTP::OTP

show all

Defined in:

lib/rotp/otp.rb

Instance Attribute Summary (collapse)

• - (Object) digest readonly

  Returns the value of attribute digest.

• - (Object) digits readonly

  Returns the value of attribute digits.

• - (Object) secret readonly

  Returns the value of attribute secret.

Instance Method Summary (collapse)

• - (Object) byte_secret
• - (Object) generate_otp(count)
• - (OTP) initialize(s, options = {}) constructor

  Params: secret in base32.

• - (Object) int_to_bytestring(int, padding = 8)

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# File 'lib/rotp/otp.rb', line 6

def initialize(s, options = {})
  @digits = options[:digits] || 6
  @digest = options[:digest] || "sha1"
  @secret = s
end

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# File 'lib/rotp/otp.rb', line 3

def digest
  @digest
end

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# File 'lib/rotp/otp.rb', line 3

def digits
  @digits
end

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# File 'lib/rotp/otp.rb', line 3

def secret
  @secret
end

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# File 'lib/rotp/otp.rb', line 27

def byte_secret
  Base32.decode(@secret)
end

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# File 'lib/rotp/otp.rb', line 12

def generate_otp(count)
  hmac = OpenSSL::HMAC.digest(
    OpenSSL::Digest::Digest.new(digest),
    byte_secret,
    int_to_bytestring(count)
  )

  offset = hmac[19] & 0xf
  code = (hmac[offset] & 0x7f) << 24 |
    (hmac[offset + 1] & 0xff) << 16 |
    (hmac[offset + 2] & 0xff) << 8 |
    (hmac[offset + 3] & 0xff)
  code % 10 ** digits
end

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# File 'lib/rotp/otp.rb', line 31

def int_to_bytestring(int, padding = 8)
  result = []
  until int == 0
    result << (int & 0xFF).chr
    int >>=  8
  end
  result.reverse.join.rjust(8, 0.chr)
end