obfuscation vs unknown quantity

obfuscation

noun
  • A single instance of intentionally obscuring the meaning of something to make it more difficult to grasp. 

  • Confusion, bewilderment, or a baffled state resulting from something obfuscated, or made more opaque and muddled with the intent to obscure information. 

  • The alteration of computer code to preserve its behavior while concealing its structure and intent. 

  • The act or process of obfuscating, or obscuring the perception of something; the concept of concealing the meaning of a communication by making it more confusing and harder to interpret. 

unknown quantity

noun
  • Used other than figuratively or idiomatically: see unknown, quantity. 

  • A person or thing whose nature or value is a mystery. 

How often have the words obfuscation and unknown quantity occurred in a corpus of books? (source: Google Ngram Viewer )