Module: Zxcvbn::Math Private

Included in:
Guesses
Defined in:
lib/zxcvbn/math.rb

Overview

This module is part of a private API. You should avoid using this module if possible, as it may be removed or be changed in the future.

Mathematical utilities used by the guess estimation logic.

Instance Method Summary collapse

Instance Method Details

#average_degree_for_graph(graph_name) ⇒ Float

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns the precomputed average key-adjacency degree for a keyboard graph.

Parameters:

  • graph_name (String) —

    e.g. “qwerty” or “keypad”

Returns:

  • (Float) 


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# File 'lib/zxcvbn/math.rb', line 33

def average_degree_for_graph(graph_name)
  data.graph_stats[graph_name][:average_degree]
end

#nCk(n, k) ⇒ Integer

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Computes the binomial coefficient C(n, k) (“n choose k”).

Parameters:

  • n (Integer)
  • k (Integer)

Returns:

  • (Integer) 


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# File 'lib/zxcvbn/math.rb', line 12

def nCk(n, k)
  return 0 if k > n
  return 1 if k.zero?

  # Use symmetry property: C(n,k) = C(n, n-k)
  # Choose smaller k to minimize iterations
  k = n - k if k > n - k

  r = 1
  (1..k).each do |d|
    r *= n
    r /= d
    n -= 1
  end
  r
end

#starting_positions_for_graph(graph_name) ⇒ Integer

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns the number of starting positions (keys) in a keyboard graph.

Parameters:

  • graph_name (String) —

    e.g. “qwerty” or “keypad”

Returns:

  • (Integer) 


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# File 'lib/zxcvbn/math.rb', line 41

def starting_positions_for_graph(graph_name)
  data.graph_stats[graph_name][:starting_positions]
end