Class: Utils::HammingDistanceFilter

Inherits:
Object
  • Object
show all
Defined in:
lib/crypto-toolbox/utils/hamming_distance_filter.rb

Instance Method Summary collapse

Instance Method Details

#shortest_distance_entries(buffer, result_entries: 4, samples: 4) ⇒ Object 



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# File 'lib/crypto-toolbox/utils/hamming_distance_filter.rb', line 3

def shortest_distance_entries(buffer,result_entries: 4,samples: 4)
  offset = 2
  distances = ((0+offset)..64).map do |keysize|
    # take the first 4 blocks of keysize length, generate all combinations (6),
    # map than to normalized hamming distance and take mean
    buffer.chunks_of(keysize)[0,samples].combination(2).map{|a,b| a.hdist(b,normalize: true)}.reduce(&:+) / 6.0
  end
  # get the min distance, find its index, convert the keylen
  distances.min(result_entries).map{|m| distances.index(m)}.map{|i| i + offset }.uniq
end