Class: Obfuskey

Inherits:
Object
  • Object
show all
Defined in:
lib/obfuskey/math.rb,
lib/obfuskey/utils.rb,
lib/obfuskey/errors.rb,
lib/obfuskey/version.rb,
lib/obfuskey/obfuskey.rb,
lib/obfuskey/alphabets.rb,
lib/obfuskey/obfusbit_schema.rb

Defined Under Namespace

Modules: Alphabets, Math, Utils Classes: BitOverflowError, DuplicateError, Error, KeyLengthError, MaximumValueError, MultiplierError, NegativeValueError, ObfusbitSchema, SchemaValidationError, UnknownKeyError

Constant Summary collapse

PRIME_MULTIPLIER = 
1.618033988749894848
VERSION = 
"0.1.0".freeze
KEY_LENGTH = 
6

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(alphabet, key_length: KEY_LENGTH, multiplier: nil) ⇒ Obfuskey

Returns a new instance of Obfuskey.



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# File 'lib/obfuskey/obfuskey.rb', line 6

def initialize(alphabet, key_length: KEY_LENGTH, multiplier: nil)
  if alphabet.chars.uniq.length != alphabet.length
    raise DuplicateError, "The alphabet contains duplicate characters."
  end

  if !multiplier.nil? && (!multiplier.is_a?(Integer) || multiplier.even?)
    raise MultiplierError, "The multiplier must be an odd integer."
  end

  @alphabet = alphabet
  @key_length = key_length
  @maximum_value = alphabet.length**key_length - 1
  @multiplier = multiplier
  @prime_multiplier = PRIME_MULTIPLIER
end

Instance Attribute Details

#alphabet ⇒ Object (readonly)

Returns the value of attribute alphabet.



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# File 'lib/obfuskey/obfuskey.rb', line 4

def alphabet
  @alphabet
end

#key_length ⇒ Object (readonly)

Returns the value of attribute key_length.



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# File 'lib/obfuskey/obfuskey.rb', line 4

def key_length
  @key_length
end

#maximum_value ⇒ Object (readonly)

Returns the value of attribute maximum_value.



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# File 'lib/obfuskey/obfuskey.rb', line 4

def maximum_value
  @maximum_value
end

Instance Method Details

#get_key(value) ⇒ Object

Raises:



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# File 'lib/obfuskey/obfuskey.rb', line 31

def get_key(value)
  raise NegativeValueError, "The value must be greater than or equal to zero." if value < 0

  if value > @maximum_value
    raise MaximumValueError, "The maximum value possible is #{@maximum_value}"
  end

  return @alphabet[0] * @key_length if value.zero?

  encoded = Utils.encode((value * multiplier) % (@maximum_value + 1), @alphabet)
  encoded.rjust(@key_length, @alphabet[0])
end

#get_value(key) ⇒ Object 



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# File 'lib/obfuskey/obfuskey.rb', line 44

def get_value(key)
  unless key.chars.all? { |c| @alphabet.include?(c) }
    raise UnknownKeyError,
      "The key contains characters not found in the current alphabet."
  end

  if key.length != @key_length
    raise KeyLengthError, "The key length does not match the set length."
  end

  return 0 if key == @alphabet[0] * @key_length

  decoded = Utils.decode(key, @alphabet)
  max_p1 = @maximum_value + 1
  decoded * Math.mod_inv(multiplier, max_p1) % max_p1
end

#multiplier ⇒ Object 



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# File 'lib/obfuskey/obfuskey.rb', line 22

def multiplier
  @multiplier ||= generate_multiplier
end

#set_prime_multiplier(prime_multiplier) ⇒ Object 



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# File 'lib/obfuskey/obfuskey.rb', line 26

def set_prime_multiplier(prime_multiplier)
  @prime_multiplier = prime_multiplier
  @multiplier = nil
end

#to_s ⇒ Object Also known as: inspect 



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# File 'lib/obfuskey/obfuskey.rb', line 61

def to_s
  multiplier_info =
    if @multiplier.nil?
      ", multiplier=auto (prime_mult=#{@prime_multiplier})"
    else
      ", multiplier=#{@multiplier}"
    end

  display_alphabet =
    if @alphabet.length > 20
      "'#{@alphabet[0, 10]}...#{@alphabet[-5, 5]}'"
    else
      "'#{@alphabet}'"
    end

  "Obfuskey(alphabet=#{display_alphabet}, key_length=#{@key_length}#{multiplier_info})"
end