title: What is the exact formula to calculate brute force password cracking time?
body: <p>Through my knowledge about this stuff, I've come up with a rough answer, but I'm in no way an expert and I want someone more knowledgeable to take a look and tell me if and where I'm wrong.</p>
  <p><strong>Premise:</strong><br />
  We'll be using brute force against a completely random password that follows no known pattern and we'll assume we're using a symmetric encryption algorithm that has no known vulnerabilities, such as AES-256.</p>
  <pre>
  s: seconds to crack
  c: length of the password in characters
  p: hashes/s of the cracking machine
  2<sup>8</sup>: possible combinations for 1 byte
  </pre>
  <p><strong>My formula:</strong></p>
  <pre>
  
      s = 2<sup>8c</sup> ÷ p
  
  </pre>
  <p>It's very optimistic since not every single byte is mapped to a possible character, but other than that is the formula correct?</p>