Class: Rocra

Inherits:
Object
  • Object
show all
Defined in:
lib/rocra.rb,
lib/rocra/version.rb

Constant Summary collapse

VERSION = 
"0.0.1"

Class Method Summary collapse

Class Method Details

.generate(ocra_suite, key, counter, question, password, session_information, timestamp) ⇒ Object

This method generates an OCRA HOTP value for the given set of parameters.

truncationDigits digits

Parameters:

  • ocraSuite —

    the OCRA Suite

  • key —

    the shared secret, HEX encoded

  • counter —

    the counter that changes on a per use basis, HEX encoded

  • question —

    the challenge question, HEX encoded

  • password —

    a password that can be used, HEX encoded

  • sessionInformation —

    Static information that identifies the current session, Hex encoded

  • timestamp —

    a value that reflects a time

Returns:

  • A numeric String in base 10 that includes



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# File 'lib/rocra.rb', line 27

def generate(ocra_suite, key, counter, question, password, session_information, timestamp)

  code_digits = 0
  crypto = ""
  result = nil
  ocra_suite_length = ocra_suite.length
  counter_length = 0
  question_length = 0
  password_length = 0

  session_information_length = 0
  timestamp_length = 0

  # How many digits should we return
  components = ocra_suite.split(':')
  cryptoFunction = components[1]
  dataInput = components[2].downcase # lower here so we can do case insensitive comparisons

  crypto = 'sha1'   if cryptoFunction.downcase.include?('sha1')
  crypto = 'sha256' if cryptoFunction.downcase.include?('sha256')
  crypto = 'sha512' if cryptoFunction.downcase.include?('sha512')

  code_digits = cryptoFunction.split('-').last

  # The size of the byte array message to be encrypted

  # Counter
  if dataInput[0,1] == "c"
    # Fix the length of the HEX string
    counter_length=8
    counter = counter.rjust(16, '0')
  end

  # Question
  if dataInput[0,1] == "q" || dataInput.include?('-q')
    question = question.ljust(256, '0')
    question_length = 128
  end

  # Password
  if dataInput.include?("psha1")
    password = password.ljust(40, '0')
    password_length = 20
  end

  if dataInput.include?("psha256")
    password = password.ljust(64, '0')
    password_length = 32
  end

  if dataInput.include?("psha512")
    password = password.ljust(128, '0')
    password_length = 64
  end

  # session_information
  if dataInput.include?("s064")
    session_information = session_information.ljust(128, '0')
    session_information_length = 64
  end

  if dataInput.include?("s128")
    session_information = session_information.ljust(256, '0')
    session_information_length = 128
  end

  if dataInput.include?("s256")
    session_information = session_information.ljust(512, '0')
    session_information_length = 256
  end

  if dataInput.include?("s512")
    session_information = session_information.ljust(128, '0')
    session_information_length = 64
  end

  # TimeStamp
  if dataInput[0,1] == "t" || dataInput.include?("-t")
    timestamp = timestamp.rjust(16, '0')
    timestamp_length = 8
  end

  # Put the bytes of "ocra_suite" parameters into the message
  length = ocra_suite_length +
    counter_length +
    question_length +
    password_length +
    session_information_length +
    timestamp_length + 1
  msg = "\0" * length
  msg[0, ocra_suite.length] = ocra_suite

  # Delimiter
  # msg[ocra_suite.length] = hex2str("0")

  # Put the bytes of "Counter" to the message
  # Input is HEX encoded
  if counter_length > 0
    pos = ocra_suite_length + 1
    msg[pos, counter.length] = hex2str(counter)
  end

  # Put the bytes of "question" to the message
  # Input is text encoded
  if question_length > 0
    pos = ocra_suite_length + 1 + counter_length
    msg[pos, question.length] = hex2str(question)
  end

  # Put the bytes of "password" to the message
  # Input is HEX encoded
  if password_length > 0
    pos = ocra_suite_length + 1 + counter_length + question_length
    msg[pos, password.length] = hex2str(password)
  end

  # Put the bytes of "session_information" to the message
  # Input is text encoded
  if session_information_length > 0
    pos = ocra_suite_length + 1 + counter_length + question_length + password_length
    msg[pos, session_information.length] = hex2str(session_information)
  end

  # Put the bytes of "time" to the message
  # Input is text value of minutes
  if timestamp_length > 0
    pos = ocra_suite_length + 1 + counter_length + question_length +
      password_length + session_information_length
    msg[pos, timestamp.length] = hex2str(timestamp)
  end

  byteKey = hex2str(key)
  hash = hmac_sha1(crypto, byteKey, msg)
  oath_truncate(hash, code_digits)

end